TUN inbound: Support autoSystemRoutingTable and autoOutboundsInterface on FreeBSD as well (#6691 )

https://github.com/XTLS/Xray-core/pull/6691#issuecomment-5445818753 Closes https://github.com/XTLS/Xray-core/issues/5594#issuecomment-4789101025
Transport: Bind the UDP outbound socket in the destination family (#6688 )
2026-10-02 05:46:39 +00:00 · 2026-08-27 22:32:45 +00:00 · 2026-08-27 21:46:26 +00:00 · 2026-08-27 17:25:56 +00:00
25 changed files with 1725 additions and 173 deletions
@@ -3,7 +3,7 @@ module github.com/xtls/xray-core
 go 1.26

 require (
-	github.com/apernet/quic-go v0.59.1-0.20260425001925-6c6cc9bcb716
+	github.com/apernet/quic-go v0.61.1-0.20260806010916-184d081eef3e
 	github.com/cloudflare/circl v1.6.5
 	github.com/ghodss/yaml v1.0.1-0.20220118164431-d8423dcdf344
 	github.com/golang/mock v1.7.0-rc.1
@@ -11,6 +11,7 @@ require (
 	github.com/google/uuid v1.6.0
 	github.com/gorilla/websocket v1.5.3
 	github.com/klauspost/cpuid/v2 v2.4.0
+	github.com/libp2p/go-nat v1.0.1-0.20250821073202-01afc089f138
 	github.com/miekg/dns v1.1.73
 	github.com/pelletier/go-toml v1.9.5
 	github.com/pion/stun/v3 v3.1.7
@@ -41,9 +42,14 @@ require (
 require (
 	github.com/andybalholm/brotli v1.0.6 // indirect
 	github.com/google/btree v1.1.2 // indirect
+	github.com/google/gopacket v1.1.19 // indirect
+	github.com/huin/goupnp v1.2.0 // indirect
+	github.com/jackpal/go-nat-pmp v1.0.2 // indirect
 	github.com/juju/ratelimit v1.0.2 // indirect
 	github.com/klauspost/compress v1.17.4 // indirect
+	github.com/koron/go-ssdp v0.0.4 // indirect
 	github.com/kr/text v0.2.0 // indirect
+	github.com/libp2p/go-netroute v0.2.1 // indirect
 	github.com/pion/dtls/v3 v3.1.5 // indirect
 	github.com/pion/logging v0.2.4 // indirect
 	github.com/pion/transport/v4 v4.1.0 // indirect
@@ -1,7 +1,7 @@
 github.com/andybalholm/brotli v1.0.6 h1:Yf9fFpf49Zrxb9NlQaluyE92/+X7UVHlhMNJN2sxfOI=
 github.com/andybalholm/brotli v1.0.6/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
-github.com/apernet/quic-go v0.59.1-0.20260425001925-6c6cc9bcb716 h1:J1O+xpLuJWkdYbw5JPGwBqIHs2J8tiEP7Py9lPqkN2I=
-github.com/apernet/quic-go v0.59.1-0.20260425001925-6c6cc9bcb716/go.mod h1:Npbg8qBtAZlsAB3FWmqwlVh5jtVG6a4DlYsOylUpvzA=
+github.com/apernet/quic-go v0.61.1-0.20260806010916-184d081eef3e h1:5mgtR5gwIgBKMiGI1QdXldZZ+SNor06Nbu1wCBulQBg=
+github.com/apernet/quic-go v0.61.1-0.20260806010916-184d081eef3e/go.mod h1:x7qxEvX6MCVtDuBKHj3E+88+BtrbEMuAL5qGUKItjW8=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cloudflare/circl v1.6.5 h1:O64F26HEqNhznd/hrC5KZXVKYuKM2rx4deZDTc4ihQA=
@@ -21,22 +21,34 @@ github.com/google/btree v1.1.2 h1:xf4v41cLI2Z6FxbKm+8Bu+m8ifhj15JuZ9sa0jZCMUU=
 github.com/google/btree v1.1.2/go.mod h1:qOPhT0dTNdNzV6Z/lhRX0YXUafgPLFUh+gZMl761Gm4=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
+github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
+github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
 github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/h12w/go-socks5 v0.0.0-20200522160539-76189e178364 h1:5XxdakFhqd9dnXoAZy1Mb2R/DZ6D1e+0bGC/JhucGYI=
 github.com/h12w/go-socks5 v0.0.0-20200522160539-76189e178364/go.mod h1:eDJQioIyy4Yn3MVivT7rv/39gAJTrA7lgmYr8EW950c=
+github.com/huin/goupnp v1.2.0 h1:uOKW26NG1hsSSbXIZ1IR7XP9Gjd1U8pnLaCMgntmkmY=
+github.com/huin/goupnp v1.2.0/go.mod h1:gnGPsThkYa7bFi/KWmEysQRf48l2dvR5bxr2OFckNX8=
+github.com/jackpal/go-nat-pmp v1.0.2 h1:KzKSgb7qkJvOUTqYl9/Hg/me3pWgBmERKrTGD7BdWus=
+github.com/jackpal/go-nat-pmp v1.0.2/go.mod h1:QPH045xvCAeXUZOxsnwmrtiCoxIr9eob+4orBN1SBKc=
 github.com/juju/ratelimit v1.0.2 h1:sRxmtRiajbvrcLQT7S+JbqU0ntsb9W2yhSdNN8tWfaI=
 github.com/juju/ratelimit v1.0.2/go.mod h1:qapgC/Gy+xNh9UxzV13HGGl/6UXNN+ct+vwSgWNm/qk=
 github.com/klauspost/compress v1.17.4 h1:Ej5ixsIri7BrIjBkRZLTo6ghwrEtHFk7ijlczPW4fZ4=
 github.com/klauspost/compress v1.17.4/go.mod h1:/dCuZOvVtNoHsyb+cuJD3itjs3NbnF6KH9zAO4BDxPM=
 github.com/klauspost/cpuid/v2 v2.4.0 h1:S6Hrbc7+ywsr0r+RLapfGBHfyefhCTwEh3A0tV913Dw=
 github.com/klauspost/cpuid/v2 v2.4.0/go.mod h1:19jmZ9mjzoF//ddRSUsv0zfBTJWh3QJh9FNxZTMrGxU=
+github.com/koron/go-ssdp v0.0.4 h1:1IDwrghSKYM7yLf7XCzbByg2sJ/JcNOZRXS2jczTwz0=
+github.com/koron/go-ssdp v0.0.4/go.mod h1:oDXq+E5IL5q0U8uSBcoAXzTzInwy5lEgC91HoKtbmZk=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/libp2p/go-nat v1.0.1-0.20250821073202-01afc089f138 h1:YohuNPT/1k3VcThCQlBZ43PCPWPfMRS1zcxWBF2SLK8=
+github.com/libp2p/go-nat v1.0.1-0.20250821073202-01afc089f138/go.mod h1:TXQg5tfSy+bUjnhT5728j5j/MBj7keIYqqZ1+8k/ui8=
+github.com/libp2p/go-netroute v0.2.1 h1:V8kVrpD8GK0Riv15/7VN6RbUQ3URNZVosw7H2v9tksU=
+github.com/libp2p/go-netroute v0.2.1/go.mod h1:hraioZr0fhBjG0ZRXJJ6Zj2IVEVNx6tDTFQfSmcq7mQ=
 github.com/miekg/dns v1.1.73 h1:uhT8nJxmTrPJYClxVxTCX+CVn6qnzSiybRk72Z6DgrE=
 github.com/miekg/dns v1.1.73/go.mod h1:RW2Obtfd5NZHvOFe3zYG0W8koWOQtAzyHaLo8vASBuQ=
 github.com/pelletier/go-toml v1.9.5 h1:4yBQzkHv+7BHq2PQUZF3Mx0IYxG7LsP222s7Agd3ve8=
@@ -53,6 +65,8 @@ github.com/pion/transport/v4 v4.1.0 h1:8S+nF2reM2cJuqC6g78OVy2BBgmbdns+acx3jA97B
 github.com/pion/transport/v4 v4.1.0/go.mod h1:06hFI+jCFcok2X2MekVufNZ/uzNZXivGBPfviSVcjgM=
 github.com/pires/go-proxyproto v0.15.0 h1:dTshmNbFm/D+0+sbrxUuddPOZ5Y0B7c5NhtsBkm6LqI=
 github.com/pires/go-proxyproto v0.15.0/go.mod h1:OXsCrKwrK2tXS9YrI5tkHx5xaQlO8FH3lFW76orFh24=
+github.com/quic-go/go-ossfuzz-seeds v0.1.0 h1:APacT+iIaNF6fd8AGEiN3bT/Jtkd2jz4v4TzM7MFjy0=
+github.com/quic-go/go-ossfuzz-seeds v0.1.0/go.mod h1:3IOHRbJIc+L6YKMwfDtJAM9Vj9k0YY4muhuyUYk5tbk=
 github.com/quic-go/qpack v0.6.0 h1:g7W+BMYynC1LbYLSqRt8PBg5Tgwxn214ZZR34VIOjz8=
 github.com/quic-go/qpack v0.6.0/go.mod h1:lUpLKChi8njB4ty2bFLX2x4gzDqXwUpaO1DP9qMDZII=
 github.com/refraction-networking/utls v1.8.3-0.20260301010127-aa6edf4b11af h1:er2acxbi3N1nvEq6HXHUAR1nTWEJmQfqiGR8EVT9rfs=
@@ -100,6 +114,8 @@ golang.org/x/crypto v0.55.0 h1:+KWHjbgOaAQ66dh/YlkZKHlz9ZUlq61AFirAR9ntP8M=
 golang.org/x/crypto v0.55.0/go.mod h1:uq0V9dE/fzQuJtbnL+2EhWOE63vo164FY8xqEnV9xis=
 golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842 h1:vr/HnozRka3pE4EsMEg1lgkXJkTFJCVUX+S/ZT6wYzM=
 golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842/go.mod h1:XtvwrStGgqGPLc4cjQfWqZHG1YFdYs6swckp8vpsjnc=
+golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
+golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/mod v0.5.1/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
@@ -129,6 +145,7 @@ golang.org/x/time v0.14.0 h1:MRx4UaLrDotUKUdCIqzPC48t1Y9hANFKIRpNx+Te8PI=
 golang.org/x/time v0.14.0/go.mod h1:eL/Oa2bBBK0TkX57Fyni+NgnyQQN4LitPmob2Hjnqw4=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/tools v0.1.8/go.mod h1:nABZi5QlRsZVlzPpHl034qft6wpY4eDcsTt5AaioBiU=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
@@ -816,9 +816,11 @@ func (c *Xicmp) Build() (proto.Message, error) {
 }

 type Realm struct {
-	Url         string     `json:"url"`
-	StunServers []string   `json:"stunServers"`
-	TlsConfig   *TLSConfig `json:"tlsConfig"`
+	Url         string             `json:"url"`
+	StunServers []string           `json:"stunServers"`
+	TlsConfig   *TLSConfig         `json:"tlsConfig"`
+	IPMode      string             `json:"ipMode"`
+	PortMapping *realm.PortMapping `json:"portMapping"`
 }

 func (c *Realm) Build() (proto.Message, error) {
@@ -898,6 +900,8 @@ func (c *Realm) Build() (proto.Message, error) {
 		ID:          id,
 		StunServers: stunServers,
 		TlsConfig:   tlsConfig,
+		IPMode:      strings.ToLower(c.IPMode),
+		PortMapping: c.PortMapping,
 	}, nil
 }

@@ -928,20 +932,24 @@ func (c *Mask) Build(tcp bool) (proto.Message, error) {
 }

 type QuicParamsConfig struct {
-	Congestion                  string    `json:"congestion"`
-	Debug                       bool      `json:"debug"`
-	BbrProfile                  string    `json:"bbrProfile"`
-	BrutalUp                    Bandwidth `json:"brutalUp"`
-	BrutalDown                  Bandwidth `json:"brutalDown"`
-	UdpHop                      UdpHop    `json:"udpHop"`
-	InitStreamReceiveWindow     uint64    `json:"initStreamReceiveWindow"`
-	MaxStreamReceiveWindow      uint64    `json:"maxStreamReceiveWindow"`
-	InitConnectionReceiveWindow uint64    `json:"initConnectionReceiveWindow"`
-	MaxConnectionReceiveWindow  uint64    `json:"maxConnectionReceiveWindow"`
-	MaxIdleTimeout              int64     `json:"maxIdleTimeout"`
-	KeepAlivePeriod             int64     `json:"keepAlivePeriod"`
-	DisablePathMTUDiscovery     bool      `json:"disablePathMTUDiscovery"`
-	MaxIncomingStreams          int64     `json:"maxIncomingStreams"`
+	Congestion                    string    `json:"congestion"`
+	Debug                         bool      `json:"debug"`
+	BbrProfile                    string    `json:"bbrProfile"`
+	BrutalUp                      Bandwidth `json:"brutalUp"`
+	BrutalDown                    Bandwidth `json:"brutalDown"`
+	BrutalDisableLossCompensation bool      `json:"brutalDisableLossCompensation"`
+	UdpHop                        UdpHop    `json:"udpHop"`
+	InitStreamReceiveWindow       uint64    `json:"initStreamReceiveWindow"`
+	MaxStreamReceiveWindow        uint64    `json:"maxStreamReceiveWindow"`
+	InitConnectionReceiveWindow   uint64    `json:"initConnectionReceiveWindow"`
+	MaxConnectionReceiveWindow    uint64    `json:"maxConnectionReceiveWindow"`
+	MaxIdleTimeout                int64     `json:"maxIdleTimeout"`
+	KeepAlivePeriod               int64     `json:"keepAlivePeriod"`
+	DisablePathMTUDiscovery       bool      `json:"disablePathMTUDiscovery"`
+	DisableChromeParrot           bool      `json:"disableChromeParrot"`
+	DisableGSO                    bool      `json:"disableGSO"`
+	MaxIncomingStreams            int64     `json:"maxIncomingStreams"`
+	DisableStatelessReset         bool      `json:"disableStatelessReset"`
 }

 type FinalMask struct {
@@ -285,10 +285,11 @@ func (c *StreamConfig) Build() (*internet.StreamConfig, error) {
 			}

 			config.QuicParams = &internet.QuicParams{
-				Congestion: c.FinalMask.QuicParams.Congestion,
-				BbrProfile: profile,
-				BrutalUp:   up,
-				BrutalDown: down,
+				Congestion:                    c.FinalMask.QuicParams.Congestion,
+				BbrProfile:                    profile,
+				BrutalUp:                      up,
+				BrutalDown:                    down,
+				BrutalDisableLossCompensation: c.FinalMask.QuicParams.BrutalDisableLossCompensation,
 				UdpHop: &internet.UdpHop{
 					Ports:       c.FinalMask.QuicParams.UdpHop.PortList.Build().Ports(),
 					IntervalMin: int64(c.FinalMask.QuicParams.UdpHop.Interval.From),
@@ -301,7 +302,10 @@ func (c *StreamConfig) Build() (*internet.StreamConfig, error) {
 				MaxIdleTimeout:          c.FinalMask.QuicParams.MaxIdleTimeout,
 				KeepAlivePeriod:         c.FinalMask.QuicParams.KeepAlivePeriod,
 				DisablePathMtuDiscovery: c.FinalMask.QuicParams.DisablePathMTUDiscovery,
+				DisableChromeParrot:     c.FinalMask.QuicParams.DisableChromeParrot,
+				DisableGSO:              c.FinalMask.QuicParams.DisableGSO,
 				MaxIncomingStreams:      c.FinalMask.QuicParams.MaxIncomingStreams,
+				DisableStatelessReset:   c.FinalMask.QuicParams.DisableStatelessReset,
 			}
 		}
 	}
@@ -751,6 +751,7 @@ type Masquerade struct {

 	Url         string `json:"url"`
 	RewriteHost bool   `json:"rewriteHost"`
+	XForwarded  bool   `json:"xForwarded"`
 	Insecure    bool   `json:"insecure"`

 	Content    string            `json:"content"`
@@ -791,6 +792,7 @@ func (c *HysteriaConfig) Build() (proto.Message, error) {
 	config.MasqFile = c.Masquerade.Dir
 	config.MasqUrl = c.Masquerade.Url
 	config.MasqUrlRewriteHost = c.Masquerade.RewriteHost
+	config.MasqUrlXForwarded = c.Masquerade.XForwarded
 	config.MasqUrlInsecure = c.Masquerade.Insecure
 	config.MasqString = c.Masquerade.Content
 	config.MasqStringHeaders = c.Masquerade.Headers
@@ -3,28 +3,60 @@
 package tun

 import (
+	"context"
 	"errors"
 	"net"
-	_ "unsafe"
+	"net/netip"
+	"os"
+	"slices"
+	"sync"
+	"unsafe"

 	"golang.zx2c4.com/wireguard/tun"
 	"gvisor.dev/gvisor/pkg/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"

+	"golang.org/x/net/route"
 	"golang.org/x/sys/unix"

 	"github.com/xtls/xray-core/common/buf"
+	xerrors "github.com/xtls/xray-core/common/errors"
 )

-const tunHeaderSize = 4
+const (
+	tunHeaderSize         = 4
+	defaultFreeBSDGateway = "169.254.10.1/30"
+
+	// escapeFib is the routing table outbound sockets are switched to so
+	// their traffic bypasses the TUN routes installed in the default FIB
+	// (FreeBSD's substitute for the per-socket interface binding other
+	// platforms use). Requires the boot tunable net.fibs >= 2.
+	escapeFib = 1
+)

 //go:linkname procyield runtime.procyield
 func procyield(cycles uint32)

 type FreeBSDTun struct {
-	device tun.Device
-	mtu    uint32
+	device        tun.Device
+	options       *Config
+	tunIndex      int
+	autoInterface bool
+
+	systemRoutes     []netip.Prefix
+	escapeMu         sync.Mutex
+	escapeRoutes     []escapeRoute
+	routeMonitor     *os.File
+	routeMonitorOnce sync.Once
+}
+
+// escapeRoute remembers one route written into the escape FIB, in the exact
+// shape needed to delete it again. A zero gateway means an interface route.
+type escapeRoute struct {
+	prefix  netip.Prefix
+	ifIndex int
+	gateway netip.Addr
 }

 var (
@@ -34,20 +66,172 @@ var (

 // NewTun builds new tun interface handler
 func NewTun(options *Config) (Tun, error) {
+	gateway, local, err := selectFreeBSDGateway(options.Gateway)
+	if err != nil {
+		return nil, err
+	}
+
+	// net.fibs is a boot-time constant, so validate the escape routing table
+	// before the shared handler registers a dialer controller that would
+	// otherwise steer every outbound socket into a table that was never set up.
+	if options.AutoOutboundsInterface != "" {
+		if err := checkEscapeFib(); err != nil {
+			return nil, err
+		}
+	}
+
 	tunDev, err := tun.CreateTUN(options.Name, int(options.MTU))
 	if err != nil {
 		return nil, err
 	}

-	return &FreeBSDTun{device: tunDev, mtu: options.MTU}, nil
+	name, err := tunDev.Name()
+	if err != nil {
+		_ = tunDev.Close()
+		return nil, err
+	}
+	// From here the interface exists in the kernel; the wireguard library does
+	// not remove it on Close, so every failure path must destroy it too or the
+	// next start fails with "interface already exists".
+	iface, err := net.InterfaceByName(name)
+	if err != nil {
+		_ = tunDev.Close()
+		destroyInterface(name)
+		return nil, err
+	}
+	if err := setIPAddress(name, gateway, local, iface.Index); err != nil {
+		_ = tunDev.Close()
+		destroyInterface(name)
+		return nil, err
+	}
+
+	return &FreeBSDTun{
+		device:        tunDev,
+		options:       options,
+		tunIndex:      iface.Index,
+		autoInterface: options.AutoOutboundsInterface != "",
+	}, nil
+}
+
+// selectFreeBSDGateway picks the first IPv4 prefix from the configured gateway
+// list and the local address derived from it (the darwin semantics: the
+// gateway is the remote side of the point-to-point pair, the local address is
+// the next one after it), falling back to the same link-local default.
+func selectFreeBSDGateway(configured []string) (netip.Prefix, netip.Addr, error) {
+	gateway := netip.MustParsePrefix(defaultFreeBSDGateway)
+	if len(configured) > 0 {
+		found := false
+		for _, value := range configured {
+			prefix, err := netip.ParsePrefix(value)
+			if err != nil {
+				return netip.Prefix{}, netip.Addr{}, xerrors.New("invalid FreeBSD gateway ", value).Base(err)
+			}
+			if prefix.Addr().Is4() {
+				gateway, found = prefix, true
+				break
+			}
+		}
+		if !found {
+			return netip.Prefix{}, netip.Addr{}, xerrors.New("FreeBSD gateway requires at least one IPv4 prefix")
+		}
+	}
+
+	local, ok := nextLocalIPv4(gateway)
+	if !ok || !gateway.Contains(local) {
+		return netip.Prefix{}, netip.Addr{}, xerrors.New("FreeBSD gateway ", gateway.String(), " must contain at least one usable local IPv4 address after the gateway address")
+	}
+	return gateway, local, nil
+}
+
+func nextLocalIPv4(gateway netip.Prefix) (netip.Addr, bool) {
+	local4 := gateway.Addr().As4()
+	for i := len(local4) - 1; i >= 0; i-- {
+		local4[i]++
+		if local4[i] != 0 {
+			return netip.AddrFrom4(local4), true
+		}
+	}
+	return netip.Addr{}, false
 }

 func (t *FreeBSDTun) Start() error {
+	if err := t.setSystemRoutes(); err != nil {
+		return err
+	}
+
+	// Gate on this instance's own option, not the package-global updater,
+	// which a previously-removed inbound may have left set. checkEscapeFib
+	// already ran in NewTun, before the dialer controller was registered.
+	if t.autoInterface {
+		if err := t.syncEscapeFib(); err != nil {
+			_ = t.unsetSystemRoutes()
+			return err
+		}
+		fd, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, 0)
+		if err != nil {
+			t.unsetEscapeFib()
+			_ = t.unsetSystemRoutes()
+			return err
+		}
+		t.routeMonitor = os.NewFile(uintptr(fd), "xray-route-monitor")
+		go t.monitorRouteChanges()
+	}
 	return nil
 }

+// monitorRouteChanges refreshes the outbound interface and the escape FIB
+// mirror whenever the system routing table changes.
+func (t *FreeBSDTun) monitorRouteChanges() {
+	buffer := make([]byte, 64*1024)
+	for {
+		if _, err := t.routeMonitor.Read(buffer); err != nil {
+			if !errors.Is(err, os.ErrClosed) {
+				xerrors.LogInfoInner(context.Background(), err, "[tun] failed to monitor route changes")
+			}
+			return
+		}
+		if updater != nil {
+			updater.Update()
+		}
+		if err := t.syncEscapeFib(); err != nil {
+			xerrors.LogInfoInner(context.Background(), err, "[tun] failed to refresh escape routes")
+		}
+	}
+}
+
 func (t *FreeBSDTun) Close() error {
-	return t.device.Close()
+	t.routeMonitorOnce.Do(func() {
+		if t.routeMonitor != nil {
+			_ = t.routeMonitor.Close()
+		}
+	})
+	t.unsetEscapeFib()
+	routeErr := t.unsetSystemRoutes()
+	name, nameErr := t.Name()
+	closeErr := t.device.Close()
+	// The wireguard tun device does not tear the interface down on FreeBSD,
+	// so an unclean shutdown would leave utun<n> behind and the next start
+	// would fail with "interface already exists"; destroy it explicitly.
+	if nameErr == nil {
+		destroyInterface(name)
+	}
+	return xerrors.Combine(routeErr, closeErr)
+}
+
+func destroyInterface(name string) {
+	fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
+	if err != nil {
+		return
+	}
+	defer unix.Close(fd)
+	// struct ifreq: 16-byte name + a 16-byte union (SIOCIFDESTROY's encoded
+	// length is 32 bytes on amd64, and the kernel copies in all of it).
+	var req struct {
+		Name [unix.IFNAMSIZ]byte
+		_    [16]byte
+	}
+	copy(req.Name[:], name)
+	_ = ioctlPtr(fd, unix.SIOCIFDESTROY, unsafe.Pointer(&req))
 }

 func (t *FreeBSDTun) Name() (string, error) {
@@ -55,21 +239,13 @@ func (t *FreeBSDTun) Name() (string, error) {
 }

 func (t *FreeBSDTun) Index() (int, error) {
-	name, err := t.Name()
-	if err != nil {
-		return 0, err
-	}
-	iface, err := net.InterfaceByName(name)
-	if err != nil {
-		return 0, err
-	}
-	return iface.Index, nil
+	return t.tunIndex, nil
 }

 // WritePacket implements GVisorDevice method to write one packet to the tun device
 func (t *FreeBSDTun) WritePacket(packet *stack.PacketBuffer) tcpip.Error {
 	// request memory to write from reusable buffer pool
-	b := buf.NewWithSize(int32(t.mtu) + tunHeaderSize)
+	b := buf.NewWithSize(int32(t.options.MTU) + tunHeaderSize)
 	defer b.Release()

 	// prepare Unix specific packet header
@@ -104,7 +280,7 @@ func (t *FreeBSDTun) WritePacket(packet *stack.PacketBuffer) tcpip.Error {
 // which will make the stack call Wait which should implement desired push-back
 func (t *FreeBSDTun) ReadPacket() (byte, *stack.PacketBuffer, error) {
 	// request memory to write from reusable buffer pool
-	b := buf.NewWithSize(int32(t.mtu) + tunHeaderSize)
+	b := buf.NewWithSize(int32(t.options.MTU) + tunHeaderSize)

 	// read the bytes to the interface file
 	n, err := b.ReadFrom(t.device.File())
@@ -141,23 +317,551 @@ func (t *FreeBSDTun) Wait() {
 }

 func (t *FreeBSDTun) newEndpoint() (stack.LinkEndpoint, error) {
-	return &LinkEndpoint{deviceMTU: t.mtu, device: t}, nil
+	return &LinkEndpoint{deviceMTU: t.options.MTU, device: t}, nil
 }

-func setinterface(network, address string, fd uintptr, iface *net.Interface) error {
+const (
+	IN6_IFF_NODAD         = 0x0020     // netinet6/in6_var.h
+	ND6_INFINITE_LIFETIME = 0xFFFFFFFF // netinet6/nd6.h
+)
+
+// ifAliasReq4 is struct in_aliasreq from netinet/in_var.h in the 64-byte
+// layout unix.SIOCAIFADDR encodes (name + addr/dstaddr/mask sockaddrs).
+type ifAliasReq4 struct {
+	Name    [unix.IFNAMSIZ]byte
+	Addr    unix.RawSockaddrInet4
+	Dstaddr unix.RawSockaddrInet4
+	Mask    unix.RawSockaddrInet4
+}
+
+// ifAliasReq6 is struct in6_aliasreq from netinet6/in6_var.h. The trailing
+// Vhid field matters: unix.SIOCAIFADDR_IN6 is not in x/sys/unix, so
+// siocaifaddrIn6 is derived from this struct's size, and the kernel only
+// accepts the ioctl whose encoded length matches the real struct.
+type ifAliasReq6 struct {
+	Name       [unix.IFNAMSIZ]byte
+	Addr       unix.RawSockaddrInet6
+	Dstaddr    unix.RawSockaddrInet6
+	Prefixmask unix.RawSockaddrInet6
+	Flags      int32
+	Lifetime   addrLifetime6
+	Vhid       int32
+}
+
+// addrLifetime6 is struct in6_addrlifetime (time_t is int64 on freebsd/amd64).
+type addrLifetime6 struct {
+	Expire    int64
+	Preferred int64
+	Vltime    uint32
+	Pltime    uint32
+}
+
+// SIOCAIFADDR_IN6 = _IOW('i', 27, struct in6_aliasreq); x/sys/unix does not
+// carry the netinet6 ioctls, so encode it from the struct size like the
+// header macro does.
+const siocaifaddrIn6 = 0x80000000 | (uintptr(unsafe.Sizeof(ifAliasReq6{})) << 16) | ('i' << 8) | 27
+
+// setIPAddress assigns the local/remote point-to-point IPv4 pair and a
+// link-local IPv6 address to the interface, required for the routing to work
+// (same scheme as the darwin implementation: local address is the one right
+// after the gateway address).
+func setIPAddress(name string, gateway netip.Prefix, local netip.Addr, ifIndex int) error {
+	socket4, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
+	if err != nil {
+		return err
+	}
+	defer unix.Close(socket4)
+
+	local4 := local.As4()
+
+	ifReq4 := ifAliasReq4{
+		Addr: unix.RawSockaddrInet4{
+			Len:    unix.SizeofSockaddrInet4,
+			Family: unix.AF_INET,
+			Addr:   local4,
+		},
+		Dstaddr: unix.RawSockaddrInet4{
+			Len:    unix.SizeofSockaddrInet4,
+			Family: unix.AF_INET,
+			Addr:   gateway.Addr().As4(),
+		},
+		Mask: unix.RawSockaddrInet4{
+			Len:    unix.SizeofSockaddrInet4,
+			Family: unix.AF_INET,
+			Addr:   prefixMask4(gateway.Bits()),
+		},
+	}
+	copy(ifReq4.Name[:], name)
+	if err = ioctlPtr(socket4, unix.SIOCAIFADDR, unsafe.Pointer(&ifReq4)); err != nil {
+		return os.NewSyscallError("SIOCAIFADDR", err)
+	}
+
+	socket6, err := unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM, 0)
+	if err != nil {
+		return err
+	}
+	defer unix.Close(socket6)
+
+	// link-local ipv6 address with suffix from ipv4, enough for v6 interface
+	// routes to be attachable (darwin parity); a link-local address needs its
+	// scope, which for FreeBSD ioctls is the interface index
+	local6 := netip.AddrFrom16([16]byte{0: 0xfe, 1: 0x80, 12: local4[0], 13: local4[1], 14: local4[2], 15: local4[3]})
+
+	ifReq6 := ifAliasReq6{
+		Addr: unix.RawSockaddrInet6{
+			Len:      unix.SizeofSockaddrInet6,
+			Family:   unix.AF_INET6,
+			Addr:     local6.As16(),
+			Scope_id: uint32(ifIndex),
+		},
+		Prefixmask: unix.RawSockaddrInet6{
+			Len:    unix.SizeofSockaddrInet6,
+			Family: unix.AF_INET6,
+			Addr:   prefixMask6(64),
+		},
+		Flags: IN6_IFF_NODAD,
+		Lifetime: addrLifetime6{
+			Vltime: ND6_INFINITE_LIFETIME,
+			Pltime: ND6_INFINITE_LIFETIME,
+		},
+	}
+	copy(ifReq6.Name[:], name)
+	if err = ioctlPtr(socket6, uint(siocaifaddrIn6), unsafe.Pointer(&ifReq6)); err != nil {
+		// non-fatal: FreeBSD auto-configures a link-local address on UP
+		// interfaces, which is all the v6 interface routes need
+		xerrors.LogInfoInner(context.Background(), os.NewSyscallError("SIOCAIFADDR_IN6", err), "[tun] failed to assign the IPv6 link-local address")
+	}
+
 	return nil
 }

-func findOutboundInterface(tunIndex int, fixedName string) (*net.Interface, error) {
-	if fixedName == "" {
-		return nil, errors.New("automatic outbound interface selection is not supported on this platform")
+func ioctlPtr(fd int, req uint, arg unsafe.Pointer) error {
+	_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uintptr(req), uintptr(arg))
+	if errno != 0 {
+		return errno
 	}
-	iface, err := net.InterfaceByName(fixedName)
+	return nil
+}
+
+func prefixMask4(bits int) [4]byte {
+	var mask [4]byte
+	copy(mask[:], net.CIDRMask(bits, 32))
+	return mask
+}
+
+func prefixMask6(bits int) [16]byte {
+	var mask [16]byte
+	copy(mask[:], net.CIDRMask(bits, 128))
+	return mask
+}
+
+// setinterface is the per-socket half of autoOutboundsInterface. FreeBSD has
+// no SO_BINDTODEVICE/IP_BOUND_IF equivalent, so the socket is pointed at the
+// escape FIB instead, where Start() mirrors the physical default route; the
+// iface argument is resolved by the shared updater but unused here (the escape
+// is table-based, not a per-socket interface bind). checkEscapeFib in NewTun
+// guarantees the FIB exists before this can run.
+func setinterface(network, address string, fd uintptr, iface *net.Interface) error {
+	return unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_SETFIB, escapeFib)
+}
+
+func (t *FreeBSDTun) setSystemRoutes() error {
+	routes, err := buildSystemRoutes(t.options.AutoSystemRoutingTable)
+	if err != nil {
+		return err
+	}
+	// Route through the interface, not a gateway: the tun(4) device is a
+	// broadcast interface here, so its point-to-point peer address doubles as
+	// the subnet broadcast and the kernel refuses to route to it (EACCES).
+	// Interface routes sidestep the gateway entirely (what wg-quick does on
+	// FreeBSD).
+	for _, destination := range routes {
+		if err := execRoute(-1, unix.RTM_ADD, t.tunIndex, destination, netip.Addr{}); err != nil {
+			_ = t.unsetSystemRoutes()
+			return xerrors.New("failed to add system route ", destination).Base(err)
+		}
+		t.systemRoutes = append(t.systemRoutes, destination)
+	}
+	return nil
+}
+
+func (t *FreeBSDTun) unsetSystemRoutes() error {
+	var errs []error
+	for i := len(t.systemRoutes) - 1; i >= 0; i-- {
+		destination := t.systemRoutes[i]
+		if err := execRoute(-1, unix.RTM_DELETE, t.tunIndex, destination, netip.Addr{}); err != nil && !errors.Is(err, unix.ESRCH) {
+			errs = append(errs, xerrors.New("failed to delete system route ", destination).Base(err))
+		}
+	}
+	t.systemRoutes = nil
+	return xerrors.Combine(errs...)
+}
+
+func buildSystemRoutes(configured []string) ([]netip.Prefix, error) {
+	routes := make([]netip.Prefix, 0, len(configured))
+	seen := make(map[netip.Prefix]struct{})
+
+	appendRoute := func(prefix netip.Prefix) {
+		prefix = prefix.Masked()
+		if _, found := seen[prefix]; found {
+			return
+		}
+		seen[prefix] = struct{}{}
+		routes = append(routes, prefix)
+	}
+
+	for _, value := range configured {
+		prefix, err := netip.ParsePrefix(value)
+		if err != nil {
+			return nil, xerrors.New("invalid system route ", value).Base(err)
+		}
+		if prefix.Bits() == 0 {
+			for _, protected := range protectedDefaultRoutes(prefix.Addr().Is4()) {
+				appendRoute(protected)
+			}
+			continue
+		}
+		appendRoute(prefix)
+	}
+
+	return routes, nil
+}
+
+// protectedDefaultRoutes splits a full default route into eight more-specific
+// prefixes covering everything but the zero /8, so the system's real default
+// route stays in place for outbound interface discovery (darwin parity).
+func protectedDefaultRoutes(ipv4 bool) []netip.Prefix {
+	routes := make([]netip.Prefix, 0, 8)
+	for i := 0; i < 8; i++ {
+		if ipv4 {
+			var address [4]byte
+			address[0] = 1 << i
+			routes = append(routes, netip.PrefixFrom(netip.AddrFrom4(address), 8-i))
+		} else {
+			var address [16]byte
+			address[0] = 1 << i
+			routes = append(routes, netip.PrefixFrom(netip.AddrFrom16(address), 8-i))
+		}
+	}
+	return routes
+}
+
+// execRoute writes one RTM message to a routing socket. fib >= 0 targets that
+// routing table via SO_SETFIB on the routing socket (what route(8) -fib
+// does); fib -1 leaves the process default table. An invalid gateway produces
+// an interface route pinned to interfaceIndex instead of a gateway route.
+func execRoute(fib int, messageType int, interfaceIndex int, destination netip.Prefix, gateway netip.Addr) error {
+	message := route.RouteMessage{
+		Type:    messageType,
+		Version: unix.RTM_VERSION,
+		Flags:   unix.RTF_STATIC | unix.RTF_GATEWAY,
+		Seq:     1,
+	}
+	if messageType == unix.RTM_ADD {
+		message.Flags |= unix.RTF_UP
+	}
+
+	var gatewayAddr route.Addr
+	switch {
+	case !gateway.IsValid():
+		message.Flags &^= unix.RTF_GATEWAY
+		message.Index = interfaceIndex
+		gatewayAddr = &route.LinkAddr{Index: interfaceIndex}
+	case gateway.Is4():
+		gatewayAddr = &route.Inet4Addr{IP: gateway.As4()}
+	default:
+		gatewayAddr = &route.Inet6Addr{IP: gateway.As16()}
+	}
+
+	if destination.Addr().Is4() {
+		message.Addrs = []route.Addr{
+			unix.RTAX_DST:     &route.Inet4Addr{IP: destination.Addr().As4()},
+			unix.RTAX_NETMASK: &route.Inet4Addr{IP: prefixMask4(destination.Bits())},
+			unix.RTAX_GATEWAY: gatewayAddr,
+		}
+	} else {
+		message.Addrs = []route.Addr{
+			unix.RTAX_DST:     &route.Inet6Addr{IP: destination.Addr().As16()},
+			unix.RTAX_NETMASK: &route.Inet6Addr{IP: prefixMask6(destination.Bits())},
+			unix.RTAX_GATEWAY: gatewayAddr,
+		}
+	}
+
+	request, err := message.Marshal()
+	if err != nil {
+		return err
+	}
+	fd, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, 0)
+	if err != nil {
+		return err
+	}
+	defer unix.Close(fd)
+	if fib >= 0 {
+		if err := unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_SETFIB, fib); err != nil {
+			return err
+		}
+	}
+	_, err = unix.Write(fd, request)
+	return err
+}
+
+func findOutboundInterface(tunIndex int, fixedName string) (*net.Interface, error) {
+	if fixedName != "" {
+		iface, err := net.InterfaceByName(fixedName)
+		if err != nil {
+			return nil, err
+		}
+		if iface.Index == tunIndex {
+			return nil, errors.New("outbound interface cannot be the TUN interface")
+		}
+		return iface, nil
+	}
+
+	physical, err := physicalDefaultRoutes(tunIndex, 0)
 	if err != nil {
 		return nil, err
 	}
-	if iface.Index == tunIndex {
-		return nil, errors.New("outbound interface cannot be the TUN interface")
+	for _, family := range []int{unix.AF_INET, unix.AF_INET6} {
+		for _, route := range physical {
+			if route.family == family {
+				return route.iface, nil
+			}
+		}
+	}
+	return nil, errors.New("default route not found")
+}
+
+// physicalRoute describes one physical default route: the interface it
+// leaves through, its gateway, and the connected prefix that makes the
+// gateway resolvable.
+type physicalRoute struct {
+	family    int
+	iface     *net.Interface
+	gateway   netip.Addr
+	connected netip.Prefix
+}
+
+// physicalDefaultRoutes scans the default routing table for default routes
+// that do not go through the TUN interface, at most one per address family
+// (the first usable one wins, matching the darwin implementation's
+// preference order). A non-zero onlyIndex restricts the scan to that
+// interface, for the fixed-name mode of autoOutboundsInterface.
+func physicalDefaultRoutes(tunIndex int, onlyIndex int) ([]physicalRoute, error) {
+	rib, err := route.FetchRIB(unix.AF_UNSPEC, route.RIBTypeRoute, 0)
+	if err != nil {
+		return nil, err
+	}
+	messages, err := route.ParseRIB(route.RIBTypeRoute, rib)
+	if err != nil {
+		return nil, err
+	}
+
+	found := make([]physicalRoute, 0, 2)
+	seen := make(map[int]bool)
+	for _, message := range messages {
+		routeMessage, ok := message.(*route.RouteMessage)
+		if !ok || routeMessage.Index == tunIndex {
+			continue
+		}
+		if onlyIndex != 0 && routeMessage.Index != onlyIndex {
+			continue
+		}
+		if routeMessage.Flags&unix.RTF_UP == 0 || routeMessage.Flags&unix.RTF_GATEWAY == 0 {
+			continue
+		}
+
+		family, ok := defaultRouteFamily(routeMessage)
+		if !ok || seen[family] {
+			continue
+		}
+		iface, err := usableInterface(routeMessage.Index)
+		if err != nil {
+			continue
+		}
+		gatewayAddr, ok := routeAddrToNetip(routeMessage.Addrs[unix.RTAX_GATEWAY])
+		if !ok {
+			continue
+		}
+		connected, err := connectedPrefix(iface, gatewayAddr)
+		if err != nil {
+			continue
+		}
+		seen[family] = true
+		found = append(found, physicalRoute{
+			family:    family,
+			iface:     iface,
+			gateway:   gatewayAddr,
+			connected: connected,
+		})
+	}
+
+	if len(found) == 0 {
+		return nil, errors.New("default route not found")
+	}
+	return found, nil
+}
+
+// defaultRouteFamily reports the address family of a RIB message that
+// represents a true default route (unspecified destination, zero mask).
+func defaultRouteFamily(message *route.RouteMessage) (int, bool) {
+	if len(message.Addrs) <= unix.RTAX_NETMASK {
+		return 0, false
+	}
+
+	switch destination := message.Addrs[unix.RTAX_DST].(type) {
+	case *route.Inet4Addr:
+		mask, ok := message.Addrs[unix.RTAX_NETMASK].(*route.Inet4Addr)
+		if !ok || destination.IP != netip.IPv4Unspecified().As4() {
+			return 0, false
+		}
+		ones, bits := net.IPMask(mask.IP[:]).Size()
+		return unix.AF_INET, ones == 0 && bits == 32
+	case *route.Inet6Addr:
+		mask, ok := message.Addrs[unix.RTAX_NETMASK].(*route.Inet6Addr)
+		if !ok || destination.IP != netip.IPv6Unspecified().As16() {
+			return 0, false
+		}
+		ones, bits := net.IPMask(mask.IP[:]).Size()
+		return unix.AF_INET6, ones == 0 && bits == 128
+	default:
+		return 0, false
+	}
+}
+
+func usableInterface(index int) (*net.Interface, error) {
+	iface, err := net.InterfaceByIndex(index)
+	if err != nil {
+		return nil, err
+	}
+	if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
+		return nil, errors.New("default route interface is not usable")
 	}
 	return iface, nil
 }
+
+func routeAddrToNetip(addr route.Addr) (netip.Addr, bool) {
+	switch typed := addr.(type) {
+	case *route.Inet4Addr:
+		return netip.AddrFrom4(typed.IP), true
+	case *route.Inet6Addr:
+		return netip.AddrFrom16(typed.IP), true
+	default:
+		return netip.Addr{}, false
+	}
+}
+
+// checkEscapeFib verifies the system can host the escape routing table at
+// all: FIBs are a boot-time resource on FreeBSD.
+func checkEscapeFib() error {
+	fibs, err := unix.SysctlUint32("net.fibs")
+	if err != nil {
+		return xerrors.New("failed to read net.fibs").Base(err)
+	}
+	if fibs < 2 {
+		return errors.New("automatic outbound interface on FreeBSD needs a second routing table: add net.fibs=2 to /boot/loader.conf and reboot")
+	}
+	current, err := unix.SysctlUint32("net.my_fibnum")
+	if err != nil {
+		return xerrors.New("failed to read net.my_fibnum").Base(err)
+	}
+	if current == escapeFib {
+		return errors.New("xray runs inside routing table 1, which is reserved as the escape table; start it in another FIB")
+	}
+	return nil
+}
+
+// syncEscapeFib mirrors the physical default routes (and the connected
+// prefixes their gateways resolve through) into the escape FIB, replacing
+// whatever mirror a previous call installed. On discovery failure the old
+// mirror is kept, since a stale escape route beats none during a transient
+// route flap.
+func (t *FreeBSDTun) syncEscapeFib() error {
+	var onlyIndex int
+	if t.options.AutoOutboundsInterface != "" && updater != nil {
+		if iface := updater.Get(); iface != nil {
+			onlyIndex = iface.Index
+		}
+	}
+	physical, err := physicalDefaultRoutes(t.tunIndex, onlyIndex)
+	if err != nil {
+		return err
+	}
+
+	desired := make([]escapeRoute, 0, 2*len(physical))
+	for _, p := range physical {
+		desired = append(desired,
+			escapeRoute{prefix: p.connected, ifIndex: p.iface.Index},
+			escapeRoute{prefix: defaultPrefix(p.family), ifIndex: p.iface.Index, gateway: p.gateway},
+		)
+	}
+
+	t.escapeMu.Lock()
+	defer t.escapeMu.Unlock()
+
+	// The route monitor hears our own escape FIB writes too; rewriting an
+	// unchanged mirror on every wake-up would ping-pong forever.
+	if slices.Equal(t.escapeRoutes, desired) {
+		return nil
+	}
+
+	t.unsetEscapeFibLocked()
+	for _, entry := range desired {
+		err := execRoute(escapeFib, unix.RTM_ADD, entry.ifIndex, entry.prefix, entry.gateway)
+		if err != nil && !errors.Is(err, unix.EEXIST) {
+			return xerrors.New("failed to add escape route ", entry.prefix).Base(err)
+		}
+		t.escapeRoutes = append(t.escapeRoutes, entry)
+	}
+	return nil
+}
+
+func (t *FreeBSDTun) unsetEscapeFib() {
+	t.escapeMu.Lock()
+	defer t.escapeMu.Unlock()
+	t.unsetEscapeFibLocked()
+}
+
+func (t *FreeBSDTun) unsetEscapeFibLocked() {
+	for i := len(t.escapeRoutes) - 1; i >= 0; i-- {
+		entry := t.escapeRoutes[i]
+		err := execRoute(escapeFib, unix.RTM_DELETE, entry.ifIndex, entry.prefix, entry.gateway)
+		if err != nil && !errors.Is(err, unix.ESRCH) {
+			xerrors.LogInfoInner(context.Background(), err, "[tun] failed to delete escape route ", entry.prefix)
+		}
+	}
+	t.escapeRoutes = nil
+}
+
+func defaultPrefix(family int) netip.Prefix {
+	if family == unix.AF_INET {
+		return netip.PrefixFrom(netip.IPv4Unspecified(), 0)
+	}
+	return netip.PrefixFrom(netip.IPv6Unspecified(), 0)
+}
+
+// connectedPrefix finds the interface's address prefix containing the
+// gateway, which the escape FIB needs as an interface route so the mirrored
+// default route's gateway is resolvable there.
+func connectedPrefix(iface *net.Interface, gateway netip.Addr) (netip.Prefix, error) {
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return netip.Prefix{}, err
+	}
+	for _, addr := range addrs {
+		ipNet, ok := addr.(*net.IPNet)
+		if !ok {
+			continue
+		}
+		ip, ok := netip.AddrFromSlice(ipNet.IP)
+		if !ok {
+			continue
+		}
+		ip = ip.Unmap()
+		ones, _ := ipNet.Mask.Size()
+		prefix := netip.PrefixFrom(ip, ones).Masked()
+		if prefix.Contains(gateway.WithZone("").Unmap()) {
+			return prefix, nil
+		}
+	}
+	return netip.Prefix{}, errors.New("no connected prefix contains the gateway")
+}
@@ -0,0 +1,150 @@
+//go:build freebsd
+
+package tun
+
+import (
+	"net/netip"
+	"testing"
+
+	"golang.org/x/net/route"
+	"golang.org/x/sys/unix"
+)
+
+func TestSelectFreeBSDGatewayDefault(t *testing.T) {
+	gateway, local, err := selectFreeBSDGateway(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if gateway != netip.MustParsePrefix(defaultFreeBSDGateway) {
+		t.Fatal("expected default gateway, got ", gateway)
+	}
+	if local != netip.MustParseAddr("169.254.10.2") {
+		t.Fatal("wrong local address: ", local)
+	}
+}
+
+func TestSelectFreeBSDGatewayPicksFirstIPv4(t *testing.T) {
+	gateway, local, err := selectFreeBSDGateway([]string{"fd00::1/64", "10.0.0.1/30", "10.9.9.9/24"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if gateway != netip.MustParsePrefix("10.0.0.1/30") {
+		t.Fatal("wrong gateway: ", gateway)
+	}
+	if local != netip.MustParseAddr("10.0.0.2") {
+		t.Fatal("wrong local address: ", local)
+	}
+}
+
+func TestSelectFreeBSDGatewayRequiresIPv4(t *testing.T) {
+	if _, _, err := selectFreeBSDGateway([]string{"fd00::1/64"}); err == nil {
+		t.Fatal("expected error when no IPv4 gateway is configured")
+	}
+}
+
+func TestSelectFreeBSDGatewayRejectsGarbage(t *testing.T) {
+	if _, _, err := selectFreeBSDGateway([]string{"not-a-prefix"}); err == nil {
+		t.Fatal("expected error for invalid gateway")
+	}
+}
+
+func TestSelectFreeBSDGatewayRejectsFullPrefix(t *testing.T) {
+	// 10.0.0.255/30: the "next" local address falls outside the prefix
+	if _, _, err := selectFreeBSDGateway([]string{"10.0.0.255/30"}); err == nil {
+		t.Fatal("expected error when no usable local address follows the gateway")
+	}
+}
+
+func TestNextLocalIPv4(t *testing.T) {
+	local, ok := nextLocalIPv4(netip.MustParsePrefix("169.254.10.1/30"))
+	if !ok || local != netip.MustParseAddr("169.254.10.2") {
+		t.Fatal("wrong local address: ", local)
+	}
+}
+
+func TestBuildSystemRoutesSplitsDefault(t *testing.T) {
+	routes, err := buildSystemRoutes([]string{"0.0.0.0/0"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := []string{
+		"1.0.0.0/8", "2.0.0.0/7", "4.0.0.0/6", "8.0.0.0/5",
+		"16.0.0.0/4", "32.0.0.0/3", "64.0.0.0/2", "128.0.0.0/1",
+	}
+	if len(routes) != len(expected) {
+		t.Fatal("expected ", len(expected), " routes, got ", routes)
+	}
+	for i, want := range expected {
+		if routes[i] != netip.MustParsePrefix(want) {
+			t.Fatal("route ", i, ": expected ", want, ", got ", routes[i])
+		}
+	}
+}
+
+func TestBuildSystemRoutesSplitsDefaultIPv6(t *testing.T) {
+	routes, err := buildSystemRoutes([]string{"::/0"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(routes) != 8 || routes[7] != netip.MustParsePrefix("8000::/1") {
+		t.Fatal("unexpected v6 split: ", routes)
+	}
+}
+
+func TestBuildSystemRoutesDeduplicates(t *testing.T) {
+	routes, err := buildSystemRoutes([]string{"10.0.0.0/8", "10.1.2.3/8", "0.0.0.0/0", "0.0.0.0/0"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(routes) != 9 { // 10.0.0.0/8 once + 8 splits once
+		t.Fatal("expected 9 routes, got ", routes)
+	}
+}
+
+func TestBuildSystemRoutesRejectsGarbage(t *testing.T) {
+	if _, err := buildSystemRoutes([]string{"10.0.0.0/33"}); err == nil {
+		t.Fatal("expected error for invalid route")
+	}
+}
+
+func routeMessage(dst, mask route.Addr) *route.RouteMessage {
+	addrs := make([]route.Addr, unix.RTAX_NETMASK+1)
+	addrs[unix.RTAX_DST] = dst
+	addrs[unix.RTAX_NETMASK] = mask
+	return &route.RouteMessage{Addrs: addrs}
+}
+
+func TestDefaultRouteFamilyMatchesIPv4Default(t *testing.T) {
+	family, ok := defaultRouteFamily(routeMessage(&route.Inet4Addr{}, &route.Inet4Addr{}))
+	if !ok || family != unix.AF_INET {
+		t.Fatal("expected IPv4 default route match")
+	}
+}
+
+func TestDefaultRouteFamilyMatchesIPv6Default(t *testing.T) {
+	family, ok := defaultRouteFamily(routeMessage(&route.Inet6Addr{}, &route.Inet6Addr{}))
+	if !ok || family != unix.AF_INET6 {
+		t.Fatal("expected IPv6 default route match")
+	}
+}
+
+func TestDefaultRouteFamilyRejectsNonDefault(t *testing.T) {
+	if _, ok := defaultRouteFamily(routeMessage(
+		&route.Inet4Addr{IP: [4]byte{10, 0, 0, 0}},
+		&route.Inet4Addr{IP: [4]byte{255, 0, 0, 0}},
+	)); ok {
+		t.Fatal("non-default destination must not match")
+	}
+	if _, ok := defaultRouteFamily(routeMessage(
+		&route.Inet4Addr{},
+		&route.Inet4Addr{IP: [4]byte{255, 0, 0, 0}},
+	)); ok {
+		t.Fatal("non-zero mask must not match")
+	}
+}
+
+func TestDefaultRouteFamilyRejectsShortAddrs(t *testing.T) {
+	if _, ok := defaultRouteFamily(&route.RouteMessage{}); ok {
+		t.Fatal("message without addresses must not match")
+	}
+}
@@ -443,22 +443,26 @@ func (x *UdpHop) GetIntervalMax() int64 {
 }

 type QuicParams struct {
-	state                   protoimpl.MessageState `protogen:"open.v1"`
-	Congestion              string                 `protobuf:"bytes,1,opt,name=congestion,proto3" json:"congestion,omitempty"`
-	BbrProfile              string                 `protobuf:"bytes,2,opt,name=bbr_profile,json=bbrProfile,proto3" json:"bbr_profile,omitempty"`
-	BrutalUp                uint64                 `protobuf:"varint,3,opt,name=brutal_up,json=brutalUp,proto3" json:"brutal_up,omitempty"`
-	BrutalDown              uint64                 `protobuf:"varint,4,opt,name=brutal_down,json=brutalDown,proto3" json:"brutal_down,omitempty"`
-	UdpHop                  *UdpHop                `protobuf:"bytes,5,opt,name=udp_hop,json=udpHop,proto3" json:"udp_hop,omitempty"`
-	InitStreamReceiveWindow uint64                 `protobuf:"varint,6,opt,name=init_stream_receive_window,json=initStreamReceiveWindow,proto3" json:"init_stream_receive_window,omitempty"`
-	MaxStreamReceiveWindow  uint64                 `protobuf:"varint,7,opt,name=max_stream_receive_window,json=maxStreamReceiveWindow,proto3" json:"max_stream_receive_window,omitempty"`
-	InitConnReceiveWindow   uint64                 `protobuf:"varint,8,opt,name=init_conn_receive_window,json=initConnReceiveWindow,proto3" json:"init_conn_receive_window,omitempty"`
-	MaxConnReceiveWindow    uint64                 `protobuf:"varint,9,opt,name=max_conn_receive_window,json=maxConnReceiveWindow,proto3" json:"max_conn_receive_window,omitempty"`
-	MaxIdleTimeout          int64                  `protobuf:"varint,10,opt,name=max_idle_timeout,json=maxIdleTimeout,proto3" json:"max_idle_timeout,omitempty"`
-	KeepAlivePeriod         int64                  `protobuf:"varint,11,opt,name=keep_alive_period,json=keepAlivePeriod,proto3" json:"keep_alive_period,omitempty"`
-	DisablePathMtuDiscovery bool                   `protobuf:"varint,12,opt,name=disable_path_mtu_discovery,json=disablePathMtuDiscovery,proto3" json:"disable_path_mtu_discovery,omitempty"`
-	MaxIncomingStreams      int64                  `protobuf:"varint,13,opt,name=max_incoming_streams,json=maxIncomingStreams,proto3" json:"max_incoming_streams,omitempty"`
-	unknownFields           protoimpl.UnknownFields
-	sizeCache               protoimpl.SizeCache
+	state                         protoimpl.MessageState `protogen:"open.v1"`
+	Congestion                    string                 `protobuf:"bytes,1,opt,name=congestion,proto3" json:"congestion,omitempty"`
+	BbrProfile                    string                 `protobuf:"bytes,2,opt,name=bbr_profile,json=bbrProfile,proto3" json:"bbr_profile,omitempty"`
+	BrutalUp                      uint64                 `protobuf:"varint,3,opt,name=brutal_up,json=brutalUp,proto3" json:"brutal_up,omitempty"`
+	BrutalDown                    uint64                 `protobuf:"varint,4,opt,name=brutal_down,json=brutalDown,proto3" json:"brutal_down,omitempty"`
+	BrutalDisableLossCompensation bool                   `protobuf:"varint,5,opt,name=brutal_disable_loss_compensation,json=brutalDisableLossCompensation,proto3" json:"brutal_disable_loss_compensation,omitempty"`
+	UdpHop                        *UdpHop                `protobuf:"bytes,6,opt,name=udp_hop,json=udpHop,proto3" json:"udp_hop,omitempty"`
+	InitStreamReceiveWindow       uint64                 `protobuf:"varint,7,opt,name=init_stream_receive_window,json=initStreamReceiveWindow,proto3" json:"init_stream_receive_window,omitempty"`
+	MaxStreamReceiveWindow        uint64                 `protobuf:"varint,8,opt,name=max_stream_receive_window,json=maxStreamReceiveWindow,proto3" json:"max_stream_receive_window,omitempty"`
+	InitConnReceiveWindow         uint64                 `protobuf:"varint,9,opt,name=init_conn_receive_window,json=initConnReceiveWindow,proto3" json:"init_conn_receive_window,omitempty"`
+	MaxConnReceiveWindow          uint64                 `protobuf:"varint,10,opt,name=max_conn_receive_window,json=maxConnReceiveWindow,proto3" json:"max_conn_receive_window,omitempty"`
+	MaxIdleTimeout                int64                  `protobuf:"varint,11,opt,name=max_idle_timeout,json=maxIdleTimeout,proto3" json:"max_idle_timeout,omitempty"`
+	KeepAlivePeriod               int64                  `protobuf:"varint,12,opt,name=keep_alive_period,json=keepAlivePeriod,proto3" json:"keep_alive_period,omitempty"`
+	DisablePathMtuDiscovery       bool                   `protobuf:"varint,13,opt,name=disable_path_mtu_discovery,json=disablePathMtuDiscovery,proto3" json:"disable_path_mtu_discovery,omitempty"`
+	DisableChromeParrot           bool                   `protobuf:"varint,14,opt,name=disable_chrome_parrot,json=disableChromeParrot,proto3" json:"disable_chrome_parrot,omitempty"`
+	DisableGSO                    bool                   `protobuf:"varint,15,opt,name=disableGSO,proto3" json:"disableGSO,omitempty"`
+	MaxIncomingStreams            int64                  `protobuf:"varint,16,opt,name=max_incoming_streams,json=maxIncomingStreams,proto3" json:"max_incoming_streams,omitempty"`
+	DisableStatelessReset         bool                   `protobuf:"varint,17,opt,name=disable_stateless_reset,json=disableStatelessReset,proto3" json:"disable_stateless_reset,omitempty"`
+	unknownFields                 protoimpl.UnknownFields
+	sizeCache                     protoimpl.SizeCache
 }

 func (x *QuicParams) Reset() {
@@ -519,6 +523,13 @@ func (x *QuicParams) GetBrutalDown() uint64 {
 	return 0
 }

+func (x *QuicParams) GetBrutalDisableLossCompensation() bool {
+	if x != nil {
+		return x.BrutalDisableLossCompensation
+	}
+	return false
+}
+
 func (x *QuicParams) GetUdpHop() *UdpHop {
 	if x != nil {
 		return x.UdpHop
@@ -575,6 +586,20 @@ func (x *QuicParams) GetDisablePathMtuDiscovery() bool {
 	return false
 }

+func (x *QuicParams) GetDisableChromeParrot() bool {
+	if x != nil {
+		return x.DisableChromeParrot
+	}
+	return false
+}
+
+func (x *QuicParams) GetDisableGSO() bool {
+	if x != nil {
+		return x.DisableGSO
+	}
+	return false
+}
+
 func (x *QuicParams) GetMaxIncomingStreams() int64 {
 	if x != nil {
 		return x.MaxIncomingStreams
@@ -582,6 +607,13 @@ func (x *QuicParams) GetMaxIncomingStreams() int64 {
 	return 0
 }

+func (x *QuicParams) GetDisableStatelessReset() bool {
+	if x != nil {
+		return x.DisableStatelessReset
+	}
+	return false
+}
+
 type ProxyConfig struct {
 	state               protoimpl.MessageState `protogen:"open.v1"`
 	Tag                 string                 `protobuf:"bytes,1,opt,name=tag,proto3" json:"tag,omitempty"`
@@ -1020,7 +1052,7 @@ const file_transport_internet_config_proto_rawDesc = "" +
 	"\x06UdpHop\x12\x14\n" +
 	"\x05ports\x18\x01 \x03(\rR\x05ports\x12!\n" +
 	"\finterval_min\x18\x02 \x01(\x03R\vintervalMin\x12!\n" +
-	"\finterval_max\x18\x03 \x01(\x03R\vintervalMax\"\xf2\x04\n" +
+	"\finterval_max\x18\x03 \x01(\x03R\vintervalMax\"\xc7\x06\n" +
 	"\n" +
 	"QuicParams\x12\x1e\n" +
 	"\n" +
@@ -1030,17 +1062,23 @@ const file_transport_internet_config_proto_rawDesc = "" +
 	"bbrProfile\x12\x1b\n" +
 	"\tbrutal_up\x18\x03 \x01(\x04R\bbrutalUp\x12\x1f\n" +
 	"\vbrutal_down\x18\x04 \x01(\x04R\n" +
-	"brutalDown\x128\n" +
-	"\audp_hop\x18\x05 \x01(\v2\x1f.xray.transport.internet.UdpHopR\x06udpHop\x12;\n" +
-	"\x1ainit_stream_receive_window\x18\x06 \x01(\x04R\x17initStreamReceiveWindow\x129\n" +
-	"\x19max_stream_receive_window\x18\a \x01(\x04R\x16maxStreamReceiveWindow\x127\n" +
-	"\x18init_conn_receive_window\x18\b \x01(\x04R\x15initConnReceiveWindow\x125\n" +
-	"\x17max_conn_receive_window\x18\t \x01(\x04R\x14maxConnReceiveWindow\x12(\n" +
-	"\x10max_idle_timeout\x18\n" +
-	" \x01(\x03R\x0emaxIdleTimeout\x12*\n" +
-	"\x11keep_alive_period\x18\v \x01(\x03R\x0fkeepAlivePeriod\x12;\n" +
-	"\x1adisable_path_mtu_discovery\x18\f \x01(\bR\x17disablePathMtuDiscovery\x120\n" +
-	"\x14max_incoming_streams\x18\r \x01(\x03R\x12maxIncomingStreams\"Q\n" +
+	"brutalDown\x12G\n" +
+	" brutal_disable_loss_compensation\x18\x05 \x01(\bR\x1dbrutalDisableLossCompensation\x128\n" +
+	"\audp_hop\x18\x06 \x01(\v2\x1f.xray.transport.internet.UdpHopR\x06udpHop\x12;\n" +
+	"\x1ainit_stream_receive_window\x18\a \x01(\x04R\x17initStreamReceiveWindow\x129\n" +
+	"\x19max_stream_receive_window\x18\b \x01(\x04R\x16maxStreamReceiveWindow\x127\n" +
+	"\x18init_conn_receive_window\x18\t \x01(\x04R\x15initConnReceiveWindow\x125\n" +
+	"\x17max_conn_receive_window\x18\n" +
+	" \x01(\x04R\x14maxConnReceiveWindow\x12(\n" +
+	"\x10max_idle_timeout\x18\v \x01(\x03R\x0emaxIdleTimeout\x12*\n" +
+	"\x11keep_alive_period\x18\f \x01(\x03R\x0fkeepAlivePeriod\x12;\n" +
+	"\x1adisable_path_mtu_discovery\x18\r \x01(\bR\x17disablePathMtuDiscovery\x122\n" +
+	"\x15disable_chrome_parrot\x18\x0e \x01(\bR\x13disableChromeParrot\x12\x1e\n" +
+	"\n" +
+	"disableGSO\x18\x0f \x01(\bR\n" +
+	"disableGSO\x120\n" +
+	"\x14max_incoming_streams\x18\x10 \x01(\x03R\x12maxIncomingStreams\x126\n" +
+	"\x17disable_stateless_reset\x18\x11 \x01(\bR\x15disableStatelessReset\"Q\n" +
 	"\vProxyConfig\x12\x10\n" +
 	"\x03tag\x18\x01 \x01(\tR\x03tag\x120\n" +
 	"\x13transportLayerProxy\x18\x02 \x01(\bR\x13transportLayerProxy\"\x93\x01\n" +
@@ -75,15 +75,19 @@ message QuicParams {
  string bbr_profile = 2;
  uint64 brutal_up = 3;
  uint64 brutal_down = 4;
-  UdpHop udp_hop = 5;
-  uint64 init_stream_receive_window = 6;
-  uint64 max_stream_receive_window = 7;
-  uint64 init_conn_receive_window = 8;
-  uint64 max_conn_receive_window = 9;
-  int64 max_idle_timeout = 10;
-  int64 keep_alive_period = 11;
-  bool disable_path_mtu_discovery = 12;
-  int64 max_incoming_streams = 13;
+  bool brutal_disable_loss_compensation = 5;
+  UdpHop udp_hop = 6;
+  uint64 init_stream_receive_window = 7;
+  uint64 max_stream_receive_window = 8;
+  uint64 init_conn_receive_window = 9;
+  uint64 max_conn_receive_window = 10;
+  int64 max_idle_timeout = 11;
+  int64 keep_alive_period = 12;
+  bool disable_path_mtu_discovery = 13;
+  bool disable_chrome_parrot = 14;
+  bool disableGSO = 15;
+  int64 max_incoming_streams = 16;
+  bool disable_stateless_reset = 17;    
 }

 message ProxyConfig {
@@ -7,6 +7,7 @@ import (
 	"net/netip"
 	"slices"
 	"strings"
+	"sync"
 	"time"

 	"github.com/pion/stun/v3"
@@ -15,35 +16,67 @@ import (
 )

 type realmConnClient struct {
+	wg     sync.WaitGroup
+	ctx    context.Context
+	cancel context.CancelFunc
 	net.PacketConn
 	peer *net.UDPAddr

 	realmClient   *Client
 	realmID       string
 	stunServers   []string
+	family        Family
+	mapper        *PortMapper
 	stunTimeout   time.Duration
 	punchTimeout  time.Duration
 	punchInterval time.Duration
 }

 func NewConnClient(config *Config, raw net.PacketConn) (net.PacketConn, error) {
+	ctx, cancel := context.WithCancel(context.Background())
+
+	family := Family_Dual
+	switch config.IPMode {
+	case "dual":
+	case "v4":
+		family = Family_V4
+	case "v6":
+		family = Family_V6
+	}
+
+	var mapper *PortMapper
+	if config.PortMapping != nil && config.PortMapping.Enabled {
+		var err error
+		start := time.Now()
+		mapper, err = NewPortMapper(context.Background(), raw.LocalAddr().(*net.UDPAddr).Port, PortMapConfig{Timeout: time.Duration(config.PortMapping.Timeout) * time.Second, Lifetime: time.Duration(config.PortMapping.Lifetime) * time.Second})
+		if err != nil {
+			errors.LogErrorInner(context.Background(), err, "[realm] [port mapping] [", raw.LocalAddr().(*net.UDPAddr).Port, "] init failed after ", time.Since(start))
+		} else {
+			errors.LogDebug(context.Background(), "[realm] [port mapping] [", mapper.InternalPort(), "] gateway ", mapper.GatewayType(), ", external ", mapper.ExternalAddr())
+			errors.LogDebug(context.Background(), "[realm] [port mapping] [", mapper.InternalPort(), "] init success with ", time.Since(start))
+		}
+	}
+
 	conn := &realmConnClient{
+		ctx:        ctx,
+		cancel:     cancel,
 		PacketConn: raw,

 		realmClient:   NewClient(config.Scheme, config.Host, config.Port, config.Token, config.TlsConfig),
 		realmID:       config.ID,
 		stunServers:   config.StunServers,
+		family:        family,
+		mapper:        mapper,
 		stunTimeout:   defaultSTUNTimeout,
 		punchTimeout:  defaultPunchTimeout,
 		punchInterval: defaultPunchInterval,
 	}
-
 	return conn.getpeer()
 }

 func (c *realmConnClient) getpeer() (net.PacketConn, error) {
 	start := time.Now()
-	servers := resolveSTUNServers(c.PacketConn.LocalAddr().(*net.UDPAddr).IP, c.stunServers)
+	servers := resolveSTUNServers(c.PacketConn.LocalAddr().(*net.UDPAddr).IP, c.stunServers, c.family)
 	errors.LogDebug(context.Background(), "[realm] update stun servers ", servers, " with ", time.Since(start))
 	if len(servers) == 0 {
 		return nil, errors.New("empty locals")
@@ -70,7 +103,7 @@ func (c *realmConnClient) getpeer() (net.PacketConn, error) {

 	peers, _ := parseAddrPorts(resp.Addresses)
 	errors.LogDebug(context.Background(), "[realm] update peers ", peers)
-	filteredPeers, seen := candidatePunchAddrs(locals, peers)
+	filteredPeers, seen := candidatePunchAddrs(locals, peers, c.family)
 	errors.LogDebug(context.Background(), "[realm] filtered peers ", filteredPeers)
 	expandedPeers := expandSymmetricNATCandidates(filteredPeers, seen)
 	errors.LogDebug(context.Background(), "[realm] expanded peers ", expandedPeers)
@@ -86,6 +119,11 @@ func (c *realmConnClient) getpeer() (net.PacketConn, error) {
 	}
 	errors.LogDebug(context.Background(), "[realm] punch peer ", peer, " with ", time.Since(start))

+	if c.mapper != nil {
+		c.wg.Add(1)
+		go portMapLoop(c.ctx, c.mapper, c.wg.Done)
+	}
+
 	c.peer = peer
 	return c, nil
 }
@@ -116,10 +154,12 @@ func (c *realmConnClient) discover(servers []*net.UDPAddr) []netip.AddrPort {
 		}
 	}
 	c.PacketConn.SetReadDeadline(time.Time{})
+	if c.mapper != nil {
+		results = insertAddr(results, c.mapper.ExternalAddr())
+	}
 	slices.SortFunc(results, func(a, b netip.AddrPort) int {
 		return strings.Compare(a.String(), b.String())
 	})
-
 	return results
 }

@@ -169,3 +209,48 @@ func (c *realmConnClient) punch(meta PunchMetadata, peers []netip.AddrPort) (*ne
 func (c *realmConnClient) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	return c.PacketConn.WriteTo(p, c.peer)
 }
+
+func (c *realmConnClient) Close() error {
+	// Sadly, closing the core does not first close the sockets created for outbound connections
+	c.cancel()
+	c.wg.Wait()
+	return nil
+}
+
+func portMapLoop(ctx context.Context, mapper *PortMapper, done func()) {
+	defer func() {
+		err := mapper.Close()
+		done()
+		errors.LogDebug(context.Background(), "[realm] [port mapping] [", mapper.InternalPort(), "] removed with ", err)
+	}()
+	interval := mapper.Lifetime() / 2
+	if interval <= 0 {
+		interval = time.Minute
+	}
+	t := time.NewTicker(interval)
+	defer t.Stop()
+	failing := false
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+			changed, err := mapper.Renew(ctx)
+			if err != nil {
+				if ctx.Err() != nil {
+					return
+				}
+				if !failing {
+					errors.LogError(context.Background(), "[realm] [port mapping] [", mapper.InternalPort(), "] renewal failed")
+					failing = true
+				}
+				continue
+			}
+			errors.LogDebug(context.Background(), "[realm] [port mapping] [", mapper.InternalPort(), "] external ", mapper.ExternalAddr(), ", changed ", changed)
+			if failing {
+				errors.LogError(context.Background(), "[realm] [port mapping] [", mapper.InternalPort(), "] recovered")
+				failing = false
+			}
+		}
+	}
+}
@@ -22,6 +22,115 @@ const (
 	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
 )

+type Family int32
+
+const (
+	Family_Dual Family = 0
+	Family_V4   Family = 1
+	Family_V6   Family = 2
+)
+
+// Enum value maps for Family.
+var (
+	Family_name = map[int32]string{
+		0: "Dual",
+		1: "V4",
+		2: "V6",
+	}
+	Family_value = map[string]int32{
+		"Dual": 0,
+		"V4":   1,
+		"V6":   2,
+	}
+)
+
+func (x Family) Enum() *Family {
+	p := new(Family)
+	*p = x
+	return p
+}
+
+func (x Family) String() string {
+	return protoimpl.X.EnumStringOf(x.Descriptor(), protoreflect.EnumNumber(x))
+}
+
+func (Family) Descriptor() protoreflect.EnumDescriptor {
+	return file_transport_internet_finalmask_realm_config_proto_enumTypes[0].Descriptor()
+}
+
+func (Family) Type() protoreflect.EnumType {
+	return &file_transport_internet_finalmask_realm_config_proto_enumTypes[0]
+}
+
+func (x Family) Number() protoreflect.EnumNumber {
+	return protoreflect.EnumNumber(x)
+}
+
+// Deprecated: Use Family.Descriptor instead.
+func (Family) EnumDescriptor() ([]byte, []int) {
+	return file_transport_internet_finalmask_realm_config_proto_rawDescGZIP(), []int{0}
+}
+
+type PortMapping struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Enabled       bool                   `protobuf:"varint,1,opt,name=enabled,proto3" json:"enabled,omitempty"`
+	Timeout       int64                  `protobuf:"varint,2,opt,name=timeout,proto3" json:"timeout,omitempty"`
+	Lifetime      int64                  `protobuf:"varint,3,opt,name=lifetime,proto3" json:"lifetime,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *PortMapping) Reset() {
+	*x = PortMapping{}
+	mi := &file_transport_internet_finalmask_realm_config_proto_msgTypes[0]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *PortMapping) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*PortMapping) ProtoMessage() {}
+
+func (x *PortMapping) ProtoReflect() protoreflect.Message {
+	mi := &file_transport_internet_finalmask_realm_config_proto_msgTypes[0]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use PortMapping.ProtoReflect.Descriptor instead.
+func (*PortMapping) Descriptor() ([]byte, []int) {
+	return file_transport_internet_finalmask_realm_config_proto_rawDescGZIP(), []int{0}
+}
+
+func (x *PortMapping) GetEnabled() bool {
+	if x != nil {
+		return x.Enabled
+	}
+	return false
+}
+
+func (x *PortMapping) GetTimeout() int64 {
+	if x != nil {
+		return x.Timeout
+	}
+	return 0
+}
+
+func (x *PortMapping) GetLifetime() int64 {
+	if x != nil {
+		return x.Lifetime
+	}
+	return 0
+}
+
 type Config struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	Scheme        string                 `protobuf:"bytes,1,opt,name=scheme,proto3" json:"scheme,omitempty"`
@@ -31,13 +140,15 @@ type Config struct {
 	ID            string                 `protobuf:"bytes,5,opt,name=ID,proto3" json:"ID,omitempty"`
 	StunServers   []string               `protobuf:"bytes,6,rep,name=stun_servers,json=stunServers,proto3" json:"stun_servers,omitempty"`
 	TlsConfig     *tls.Config            `protobuf:"bytes,7,opt,name=tls_config,json=tlsConfig,proto3" json:"tls_config,omitempty"`
+	IPMode        string                 `protobuf:"bytes,8,opt,name=IPMode,proto3" json:"IPMode,omitempty"`
+	PortMapping   *PortMapping           `protobuf:"bytes,9,opt,name=port_mapping,json=portMapping,proto3" json:"port_mapping,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }

 func (x *Config) Reset() {
 	*x = Config{}
-	mi := &file_transport_internet_finalmask_realm_config_proto_msgTypes[0]
+	mi := &file_transport_internet_finalmask_realm_config_proto_msgTypes[1]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -49,7 +160,7 @@ func (x *Config) String() string {
 func (*Config) ProtoMessage() {}

 func (x *Config) ProtoReflect() protoreflect.Message {
-	mi := &file_transport_internet_finalmask_realm_config_proto_msgTypes[0]
+	mi := &file_transport_internet_finalmask_realm_config_proto_msgTypes[1]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -62,7 +173,7 @@ func (x *Config) ProtoReflect() protoreflect.Message {

 // Deprecated: Use Config.ProtoReflect.Descriptor instead.
 func (*Config) Descriptor() ([]byte, []int) {
-	return file_transport_internet_finalmask_realm_config_proto_rawDescGZIP(), []int{0}
+	return file_transport_internet_finalmask_realm_config_proto_rawDescGZIP(), []int{1}
 }

 func (x *Config) GetScheme() string {
@@ -114,11 +225,29 @@ func (x *Config) GetTlsConfig() *tls.Config {
 	return nil
 }

+func (x *Config) GetIPMode() string {
+	if x != nil {
+		return x.IPMode
+	}
+	return ""
+}
+
+func (x *Config) GetPortMapping() *PortMapping {
+	if x != nil {
+		return x.PortMapping
+	}
+	return nil
+}
+
 var File_transport_internet_finalmask_realm_config_proto protoreflect.FileDescriptor

 const file_transport_internet_finalmask_realm_config_proto_rawDesc = "" +
 	"\n" +
-	"/transport/internet/finalmask/realm/config.proto\x12'xray.transport.internet.finalmask.realm\x1a#transport/internet/tls/config.proto\"\xd5\x01\n" +
+	"/transport/internet/finalmask/realm/config.proto\x12'xray.transport.internet.finalmask.realm\x1a#transport/internet/tls/config.proto\"]\n" +
+	"\vPortMapping\x12\x18\n" +
+	"\aenabled\x18\x01 \x01(\bR\aenabled\x12\x18\n" +
+	"\atimeout\x18\x02 \x01(\x03R\atimeout\x12\x1a\n" +
+	"\blifetime\x18\x03 \x01(\x03R\blifetime\"\xc6\x02\n" +
 	"\x06Config\x12\x16\n" +
 	"\x06scheme\x18\x01 \x01(\tR\x06scheme\x12\x12\n" +
 	"\x04host\x18\x02 \x01(\tR\x04host\x12\x12\n" +
@@ -127,7 +256,13 @@ const file_transport_internet_finalmask_realm_config_proto_rawDesc = "" +
 	"\x02ID\x18\x05 \x01(\tR\x02ID\x12!\n" +
 	"\fstun_servers\x18\x06 \x03(\tR\vstunServers\x12B\n" +
 	"\n" +
-	"tls_config\x18\a \x01(\v2#.xray.transport.internet.tls.ConfigR\ttlsConfigB\x97\x01\n" +
+	"tls_config\x18\a \x01(\v2#.xray.transport.internet.tls.ConfigR\ttlsConfig\x12\x16\n" +
+	"\x06IPMode\x18\b \x01(\tR\x06IPMode\x12W\n" +
+	"\fport_mapping\x18\t \x01(\v24.xray.transport.internet.finalmask.realm.PortMappingR\vportMapping*\"\n" +
+	"\x06Family\x12\b\n" +
+	"\x04Dual\x10\x00\x12\x06\n" +
+	"\x02V4\x10\x01\x12\x06\n" +
+	"\x02V6\x10\x02B\x97\x01\n" +
 	"+com.xray.transport.internet.finalmask.realmP\x01Z<github.com/xtls/xray-core/transport/internet/finalmask/realm\xaa\x02'Xray.Transport.Internet.Finalmask.Realmb\x06proto3"

 var (
@@ -142,18 +277,22 @@ func file_transport_internet_finalmask_realm_config_proto_rawDescGZIP() []byte {
 	return file_transport_internet_finalmask_realm_config_proto_rawDescData
 }

-var file_transport_internet_finalmask_realm_config_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
+var file_transport_internet_finalmask_realm_config_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
+var file_transport_internet_finalmask_realm_config_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
 var file_transport_internet_finalmask_realm_config_proto_goTypes = []any{
-	(*Config)(nil),     // 0: xray.transport.internet.finalmask.realm.Config
-	(*tls.Config)(nil), // 1: xray.transport.internet.tls.Config
+	(Family)(0),         // 0: xray.transport.internet.finalmask.realm.Family
+	(*PortMapping)(nil), // 1: xray.transport.internet.finalmask.realm.PortMapping
+	(*Config)(nil),      // 2: xray.transport.internet.finalmask.realm.Config
+	(*tls.Config)(nil),  // 3: xray.transport.internet.tls.Config
 }
 var file_transport_internet_finalmask_realm_config_proto_depIdxs = []int32{
-	1, // 0: xray.transport.internet.finalmask.realm.Config.tls_config:type_name -> xray.transport.internet.tls.Config
-	1, // [1:1] is the sub-list for method output_type
-	1, // [1:1] is the sub-list for method input_type
-	1, // [1:1] is the sub-list for extension type_name
-	1, // [1:1] is the sub-list for extension extendee
-	0, // [0:1] is the sub-list for field type_name
+	3, // 0: xray.transport.internet.finalmask.realm.Config.tls_config:type_name -> xray.transport.internet.tls.Config
+	1, // 1: xray.transport.internet.finalmask.realm.Config.port_mapping:type_name -> xray.transport.internet.finalmask.realm.PortMapping
+	2, // [2:2] is the sub-list for method output_type
+	2, // [2:2] is the sub-list for method input_type
+	2, // [2:2] is the sub-list for extension type_name
+	2, // [2:2] is the sub-list for extension extendee
+	0, // [0:2] is the sub-list for field type_name
 }

 func init() { file_transport_internet_finalmask_realm_config_proto_init() }
@@ -166,13 +305,14 @@ func file_transport_internet_finalmask_realm_config_proto_init() {
 		File: protoimpl.DescBuilder{
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_transport_internet_finalmask_realm_config_proto_rawDesc), len(file_transport_internet_finalmask_realm_config_proto_rawDesc)),
-			NumEnums:      0,
-			NumMessages:   1,
+			NumEnums:      1,
+			NumMessages:   2,
 			NumExtensions: 0,
 			NumServices:   0,
 		},
 		GoTypes:           file_transport_internet_finalmask_realm_config_proto_goTypes,
 		DependencyIndexes: file_transport_internet_finalmask_realm_config_proto_depIdxs,
+		EnumInfos:         file_transport_internet_finalmask_realm_config_proto_enumTypes,
 		MessageInfos:      file_transport_internet_finalmask_realm_config_proto_msgTypes,
 	}.Build()
 	File_transport_internet_finalmask_realm_config_proto = out.File
@@ -8,6 +8,18 @@ option java_multiple_files = true;

 import "transport/internet/tls/config.proto";

+enum Family {
+  Dual = 0;
+  V4 = 1;
+  V6 = 2;
+}
+
+message PortMapping {
+  bool enabled = 1;
+  int64 timeout = 2;
+  int64 lifetime = 3;
+}
+
 message Config {
  string scheme = 1;
  string host = 2;
@@ -16,4 +28,6 @@ message Config {
  string ID = 5;
  repeated string stun_servers = 6;
  xray.transport.internet.tls.Config tls_config = 7;
+  string IPMode = 8;
+  PortMapping port_mapping = 9;
 }
@@ -0,0 +1,139 @@
+package realm
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/netip"
+	"sync"
+	"time"
+
+	"github.com/libp2p/go-nat"
+)
+
+const (
+	defaultPortMapTimeout  = 10 * time.Second
+	defaultPortMapLifetime = 10 * time.Minute
+
+	portMapDescription = "hysteria-realm"
+	portMapProtocol    = "udp"
+)
+
+var ErrInvalidPortMapConfig = errors.New("invalid port mapping config")
+
+type PortMapConfig struct {
+	Timeout  time.Duration
+	Lifetime time.Duration
+}
+
+func (c PortMapConfig) withDefaults() (PortMapConfig, error) {
+	if c.Timeout == 0 {
+		c.Timeout = defaultPortMapTimeout
+	}
+	if c.Timeout < 0 {
+		return c, fmt.Errorf("%w: timeout must not be negative", ErrInvalidPortMapConfig)
+	}
+	if c.Lifetime == 0 {
+		c.Lifetime = defaultPortMapLifetime
+	}
+	if c.Lifetime < 0 {
+		return c, fmt.Errorf("%w: lifetime must not be negative", ErrInvalidPortMapConfig)
+	}
+	return c, nil
+}
+
+// PortMapper maintains a UDP port mapping on the local gateway via UPnP or
+// NAT-PMP. It does not renew the mapping by itself; the caller is expected
+// to call Renew periodically (typically every Lifetime/2).
+type PortMapper struct {
+	gateway      nat.NAT
+	internalPort int
+	config       PortMapConfig
+
+	mu           sync.Mutex
+	externalAddr netip.AddrPort
+}
+
+// NewPortMapper discovers the local gateway and maps internalPort for UDP.
+// It blocks for up to 2x config.Timeout (discovery + mapping).
+func NewPortMapper(ctx context.Context, internalPort int, config PortMapConfig) (*PortMapper, error) {
+	if internalPort <= 0 || internalPort > 65535 {
+		return nil, fmt.Errorf("%w: invalid internal port %d", ErrInvalidPortMapConfig, internalPort)
+	}
+	config, err := config.withDefaults()
+	if err != nil {
+		return nil, err
+	}
+
+	discoverCtx, cancel := context.WithTimeout(ctx, config.Timeout)
+	gateway, err := nat.DiscoverGateway(discoverCtx)
+	cancel()
+	if err != nil {
+		return nil, fmt.Errorf("gateway discovery failed: %w", err)
+	}
+
+	m := &PortMapper{
+		gateway:      gateway,
+		internalPort: internalPort,
+		config:       config,
+	}
+	if _, err := m.Renew(ctx); err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
+// Renew (re-)requests the port mapping and refreshes the external address.
+// It reports whether the external address changed since the last call.
+func (m *PortMapper) Renew(ctx context.Context) (bool, error) {
+	opCtx, cancel := context.WithTimeout(ctx, m.config.Timeout)
+	defer cancel()
+	externalPort, err := m.gateway.AddPortMapping(opCtx, portMapProtocol, m.internalPort, portMapDescription, m.config.Lifetime)
+	if err != nil {
+		return false, fmt.Errorf("add port mapping failed: %w", err)
+	}
+	externalIP, err := m.gateway.GetExternalAddress()
+	if err != nil {
+		return false, fmt.Errorf("get external address failed: %w", err)
+	}
+	addr, ok := netip.AddrFromSlice(externalIP)
+	if !ok || addr.IsUnspecified() || addr.IsLoopback() {
+		return false, fmt.Errorf("gateway returned unusable external address: %s", externalIP)
+	}
+	externalAddr := netip.AddrPortFrom(addr.Unmap(), uint16(externalPort))
+
+	m.mu.Lock()
+	changed := externalAddr != m.externalAddr
+	m.externalAddr = externalAddr
+	m.mu.Unlock()
+	return changed, nil
+}
+
+// ExternalAddr returns the gateway's external IP and the mapped external port.
+func (m *PortMapper) ExternalAddr() netip.AddrPort {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.externalAddr
+}
+
+// InternalPort returns the mapped local UDP port.
+func (m *PortMapper) InternalPort() int {
+	return m.internalPort
+}
+
+// Lifetime returns the effective mapping lease duration.
+func (m *PortMapper) Lifetime() time.Duration {
+	return m.config.Lifetime
+}
+
+// GatewayType returns the protocol used to talk to the gateway ("UPnP" or "NAT-PMP").
+func (m *PortMapper) GatewayType() string {
+	return m.gateway.Type()
+}
+
+// Close removes the port mapping from the gateway. Best-effort.
+func (m *PortMapper) Close() error {
+	ctx, cancel := context.WithTimeout(context.Background(), m.config.Timeout)
+	defer cancel()
+	return m.gateway.DeletePortMapping(ctx, portMapProtocol, m.internalPort)
+}
@@ -33,14 +33,16 @@ type STUNPacketEvent struct {
 }

 type realmConnServer struct {
-	cleaned chan struct{}
-	ctx     context.Context
-	cancel  context.CancelFunc
+	wg     sync.WaitGroup
+	ctx    context.Context
+	cancel context.CancelFunc
 	net.PacketConn

 	realmClient   *Client
 	realmID       string
 	stunServers   []string
+	family        Family
+	mapper        *PortMapper
 	stunTimeout   time.Duration
 	punchTimeout  time.Duration
 	punchInterval time.Duration
@@ -57,8 +59,29 @@ type realmConnServer struct {
 func NewConnServer(config *Config, raw net.PacketConn) (net.PacketConn, error) {
 	ctx, cancel := context.WithCancel(context.Background())

+	family := Family_Dual
+	switch config.IPMode {
+	case "dual":
+	case "v4":
+		family = Family_V4
+	case "v6":
+		family = Family_V6
+	}
+
+	var mapper *PortMapper
+	if config.PortMapping != nil && config.PortMapping.Enabled {
+		var err error
+		start := time.Now()
+		mapper, err = NewPortMapper(context.Background(), raw.LocalAddr().(*net.UDPAddr).Port, PortMapConfig{Timeout: time.Duration(config.PortMapping.Timeout) * time.Second, Lifetime: time.Duration(config.PortMapping.Lifetime) * time.Second})
+		if err != nil {
+			errors.LogErrorInner(context.Background(), err, "[realm] [port mapping] [", raw.LocalAddr().(*net.UDPAddr).Port, "] init failed after ", time.Since(start))
+		} else {
+			errors.LogDebug(context.Background(), "[realm] [port mapping] [", mapper.InternalPort(), "] gateway ", mapper.GatewayType(), ", external ", mapper.ExternalAddr())
+			errors.LogDebug(context.Background(), "[realm] [port mapping] [", mapper.InternalPort(), "] init success with ", time.Since(start))
+		}
+	}
+
 	conn := &realmConnServer{
-		cleaned:    make(chan struct{}),
 		ctx:        ctx,
 		cancel:     cancel,
 		PacketConn: raw,
@@ -66,6 +89,8 @@ func NewConnServer(config *Config, raw net.PacketConn) (net.PacketConn, error) {
 		realmClient:   NewClient(config.Scheme, config.Host, config.Port, config.Token, config.TlsConfig),
 		realmID:       config.ID,
 		stunServers:   config.StunServers,
+		family:        family,
+		mapper:        mapper,
 		stunTimeout:   defaultSTUNTimeout,
 		punchTimeout:  defaultPunchTimeout,
 		punchInterval: defaultPunchInterval,
@@ -74,6 +99,12 @@ func NewConnServer(config *Config, raw net.PacketConn) (net.PacketConn, error) {
 		stun:   make(chan STUNPacketEvent, defaultEventBuffer),
 	}

+	if mapper != nil {
+		conn.wg.Add(1)
+		go portMapLoop(ctx, mapper, conn.wg.Done)
+	}
+
+	conn.wg.Add(1)
 	go conn.run()

 	return conn, nil
@@ -137,6 +168,8 @@ func (c *realmConnServer) discover(servers []*net.UDPAddr) []netip.AddrPort {
 	results := make([]netip.AddrPort, 0, len(servers))
 	for len(transactionIDs) > 0 {
 		select {
+		case <-c.ctx.Done():
+			goto end
 		case <-deadline.C:
 			goto end
 		case ev := <-c.stun:
@@ -148,6 +181,9 @@ func (c *realmConnServer) discover(servers []*net.UDPAddr) []netip.AddrPort {
 	}
 end:
 	deadline.Stop()
+	if c.mapper != nil {
+		results = insertAddr(results, c.mapper.ExternalAddr())
+	}
 	slices.SortFunc(results, func(a, b netip.AddrPort) int {
 		return strings.Compare(a.String(), b.String())
 	})
@@ -159,7 +195,7 @@ func (c *realmConnServer) getlocals(force bool) []netip.AddrPort {
 	c.localsMu.Lock()
 	if force || time.Since(c.localsLast) > defaultStunCacheTTL {
 		start := time.Now()
-		servers := resolveSTUNServers(c.PacketConn.LocalAddr().(*net.UDPAddr).IP, c.stunServers)
+		servers := resolveSTUNServers(c.PacketConn.LocalAddr().(*net.UDPAddr).IP, c.stunServers, c.family)
 		errors.LogDebug(context.Background(), "[realm] update stun servers ", servers, " with ", time.Since(start))
 		if len(servers) > 0 {
 			start = time.Now()
@@ -232,7 +268,7 @@ retry:
 	if err != nil {
 		errors.LogErrorInner(context.Background(), err, "[realm] ", c.realmID, " register session err retry in ", backoff)
 		if c.waitctx(c.ctx, backoff) {
-			close(c.cleaned)
+			c.wg.Done()
 			return
 		}
 		backoff *= 2
@@ -259,7 +295,7 @@ retry:
 	case <-c.ctx.Done():
 		_ = c.realmClient.Deregister(context.Background(), c.realmID, resp.SessionID)
 		errors.LogDebug(context.Background(), "[realm] ", c.realmID, " ", resp.SessionID, " deregistered")
-		close(c.cleaned)
+		c.wg.Done()
 		return
 	default:
 		goto retry
@@ -360,7 +396,7 @@ func (c *realmConnServer) punchEvent(ctx context.Context, sid string, ev *PunchE

 	peers, _ := parseAddrPorts(ev.Addresses)
 	errors.LogDebug(context.Background(), "[realm] ", ev.Nonce, " update peers ", peers)
-	filteredPeers, seen := candidatePunchAddrs(locals, peers)
+	filteredPeers, seen := candidatePunchAddrs(locals, peers, c.family)
 	errors.LogDebug(context.Background(), "[realm] ", ev.Nonce, " filtered peers ", filteredPeers)
 	expandedPeers := expandSymmetricNATCandidates(filteredPeers, seen)
 	errors.LogDebug(context.Background(), "[realm] ", ev.Nonce, " expanded peers ", expandedPeers)
@@ -398,6 +434,6 @@ func (c *realmConnServer) ReadFrom(p []byte) (int, net.Addr, error) {

 func (c *realmConnServer) Close() error {
 	c.cancel()
-	<-c.cleaned
+	c.wg.Wait()
 	return c.PacketConn.Close()
 }
@@ -23,14 +23,23 @@ const (
 	symmetricNATMaxPortsPerHost = 32
 )

-func resolveSTUNServers(local net.IP, servers []string) []*net.UDPAddr {
+func resolveSTUNServers(local net.IP, servers []string, family Family) []*net.UDPAddr {
 	var network string
-	if local.IsUnspecified() {
-		network = "ip"
-	} else {
-		if local.To4() != nil {
-			network = "ip4"
+	if family == Family_Dual {
+		if local.IsUnspecified() {
+			network = "ip"
 		} else {
+			if local.To4() != nil {
+				network = "ip4"
+			} else {
+				network = "ip6"
+			}
+		}
+	} else {
+		if family == Family_V4 {
+			network = "ip4"
+		}
+		if family == Family_V6 {
 			network = "ip6"
 		}
 	}
@@ -104,7 +113,7 @@ func netIPPortToAddrPort(ip net.IP, port int) (netip.AddrPort, error) {
 	return netip.AddrPortFrom(netip.AddrFrom16(addr), uint16(port)), nil
 }

-func candidatePunchAddrs(locals, peers []netip.AddrPort) ([]netip.AddrPort, map[netip.AddrPort]struct{}) {
+func candidatePunchAddrs(locals, peers []netip.AddrPort, family Family) ([]netip.AddrPort, map[netip.AddrPort]struct{}) {
 	var allow4, allow6 bool
 	for _, local := range locals {
 		if local.Addr().Is4() {
@@ -116,6 +125,12 @@ func candidatePunchAddrs(locals, peers []netip.AddrPort) ([]netip.AddrPort, map[
 			break
 		}
 	}
+	if family == Family_V4 {
+		allow6 = false
+	}
+	if family == Family_V6 {
+		allow4 = false
+	}
 	seen := make(map[netip.AddrPort]struct{}, len(peers))
 	candidates := make([]netip.AddrPort, 0, len(peers))
 	for _, peer := range peers {
@@ -218,3 +233,17 @@ func parseAddrPorts(addrs []string) ([]netip.AddrPort, error) {
 	}
 	return out, nil
 }
+
+func insertAddr(addrs []netip.AddrPort, addr netip.AddrPort) []netip.AddrPort {
+	if !addr.IsValid() {
+		return addrs
+	}
+	out := append([]netip.AddrPort(nil), addrs...)
+	i, found := slices.BinarySearchFunc(out, addr, func(a, b netip.AddrPort) int {
+		return strings.Compare(a.String(), b.String())
+	})
+	if found {
+		return out
+	}
+	return slices.Insert(out, i, addr)
+}
@@ -29,10 +29,11 @@ type Config struct {
 	MasqFile             string                 `protobuf:"bytes,5,opt,name=masq_file,json=masqFile,proto3" json:"masq_file,omitempty"`
 	MasqUrl              string                 `protobuf:"bytes,6,opt,name=masq_url,json=masqUrl,proto3" json:"masq_url,omitempty"`
 	MasqUrlRewriteHost   bool                   `protobuf:"varint,7,opt,name=masq_url_rewrite_host,json=masqUrlRewriteHost,proto3" json:"masq_url_rewrite_host,omitempty"`
-	MasqUrlInsecure      bool                   `protobuf:"varint,8,opt,name=masq_url_insecure,json=masqUrlInsecure,proto3" json:"masq_url_insecure,omitempty"`
-	MasqString           string                 `protobuf:"bytes,9,opt,name=masq_string,json=masqString,proto3" json:"masq_string,omitempty"`
-	MasqStringHeaders    map[string]string      `protobuf:"bytes,10,rep,name=masq_string_headers,json=masqStringHeaders,proto3" json:"masq_string_headers,omitempty" protobuf_key:"bytes,1,opt,name=key" protobuf_val:"bytes,2,opt,name=value"`
-	MasqStringStatusCode int32                  `protobuf:"varint,11,opt,name=masq_string_status_code,json=masqStringStatusCode,proto3" json:"masq_string_status_code,omitempty"`
+	MasqUrlXForwarded    bool                   `protobuf:"varint,8,opt,name=masq_url_x_forwarded,json=masqUrlXForwarded,proto3" json:"masq_url_x_forwarded,omitempty"`
+	MasqUrlInsecure      bool                   `protobuf:"varint,9,opt,name=masq_url_insecure,json=masqUrlInsecure,proto3" json:"masq_url_insecure,omitempty"`
+	MasqString           string                 `protobuf:"bytes,10,opt,name=masq_string,json=masqString,proto3" json:"masq_string,omitempty"`
+	MasqStringHeaders    map[string]string      `protobuf:"bytes,11,rep,name=masq_string_headers,json=masqStringHeaders,proto3" json:"masq_string_headers,omitempty" protobuf_key:"bytes,1,opt,name=key" protobuf_val:"bytes,2,opt,name=value"`
+	MasqStringStatusCode int32                  `protobuf:"varint,12,opt,name=masq_string_status_code,json=masqStringStatusCode,proto3" json:"masq_string_status_code,omitempty"`
 	unknownFields        protoimpl.UnknownFields
 	sizeCache            protoimpl.SizeCache
 }
@@ -109,6 +110,13 @@ func (x *Config) GetMasqUrlRewriteHost() bool {
 	return false
 }

+func (x *Config) GetMasqUrlXForwarded() bool {
+	if x != nil {
+		return x.MasqUrlXForwarded
+	}
+	return false
+}
+
 func (x *Config) GetMasqUrlInsecure() bool {
 	if x != nil {
 		return x.MasqUrlInsecure
@@ -141,20 +149,21 @@ var File_transport_internet_hysteria_config_proto protoreflect.FileDescriptor

 const file_transport_internet_hysteria_config_proto_rawDesc = "" +
 	"\n" +
-	"(transport/internet/hysteria/config.proto\x12 xray.transport.internet.hysteria\"\x8f\x04\n" +
+	"(transport/internet/hysteria/config.proto\x12 xray.transport.internet.hysteria\"\xc0\x04\n" +
 	"\x06Config\x12\x12\n" +
 	"\x04auth\x18\x02 \x01(\tR\x04auth\x12(\n" +
 	"\x10udp_idle_timeout\x18\x03 \x01(\x03R\x0eudpIdleTimeout\x12\x1b\n" +
 	"\tmasq_type\x18\x04 \x01(\tR\bmasqType\x12\x1b\n" +
 	"\tmasq_file\x18\x05 \x01(\tR\bmasqFile\x12\x19\n" +
 	"\bmasq_url\x18\x06 \x01(\tR\amasqUrl\x121\n" +
-	"\x15masq_url_rewrite_host\x18\a \x01(\bR\x12masqUrlRewriteHost\x12*\n" +
-	"\x11masq_url_insecure\x18\b \x01(\bR\x0fmasqUrlInsecure\x12\x1f\n" +
-	"\vmasq_string\x18\t \x01(\tR\n" +
+	"\x15masq_url_rewrite_host\x18\a \x01(\bR\x12masqUrlRewriteHost\x12/\n" +
+	"\x14masq_url_x_forwarded\x18\b \x01(\bR\x11masqUrlXForwarded\x12*\n" +
+	"\x11masq_url_insecure\x18\t \x01(\bR\x0fmasqUrlInsecure\x12\x1f\n" +
+	"\vmasq_string\x18\n" +
+	" \x01(\tR\n" +
 	"masqString\x12o\n" +
-	"\x13masq_string_headers\x18\n" +
-	" \x03(\v2?.xray.transport.internet.hysteria.Config.MasqStringHeadersEntryR\x11masqStringHeaders\x125\n" +
-	"\x17masq_string_status_code\x18\v \x01(\x05R\x14masqStringStatusCode\x1aD\n" +
+	"\x13masq_string_headers\x18\v \x03(\v2?.xray.transport.internet.hysteria.Config.MasqStringHeadersEntryR\x11masqStringHeaders\x125\n" +
+	"\x17masq_string_status_code\x18\f \x01(\x05R\x14masqStringStatusCode\x1aD\n" +
 	"\x16MasqStringHeadersEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
 	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01J\x04\b\x01\x10\x02B\x82\x01\n" +
@@ -11,12 +11,17 @@ message Config {
  string auth = 2;

  int64 udp_idle_timeout = 3;
+
  string masq_type = 4;
+
  string masq_file = 5;
+
  string masq_url = 6;
  bool masq_url_rewrite_host = 7;
-  bool masq_url_insecure = 8;
-  string masq_string = 9;
-  map<string, string> masq_string_headers = 10;
-  int32 masq_string_status_code = 11;
+  bool masq_url_x_forwarded = 8;
+  bool masq_url_insecure = 9;
+
+  string masq_string = 10;
+  map<string, string> masq_string_headers = 11;
+  int32 masq_string_status_code = 12;
 }
@@ -33,6 +33,8 @@ type BrutalSender struct {
 	pktInfoSlots [pktInfoSlotCount]pktInfo
 	ackRate      float64

+	disableLossCompensation bool
+
 	debug                 bool
 	lastAckPrintTimestamp int64
 }
@@ -43,13 +45,14 @@ type pktInfo struct {
 	LossCount uint64
 }

-func NewBrutalSender(bps uint64) *BrutalSender {
+func NewBrutalSender(bps uint64, disableLossCompensation bool) *BrutalSender {
 	debug, _ := strconv.ParseBool(os.Getenv(debugEnv))
 	bs := &BrutalSender{
-		bps:             congestion.ByteCount(bps),
-		maxDatagramSize: congestion.InitialPacketSize,
-		ackRate:         1,
-		debug:           debug,
+		bps:                     congestion.ByteCount(bps),
+		maxDatagramSize:         congestion.InitialPacketSize,
+		ackRate:                 1,
+		disableLossCompensation: disableLossCompensation,
+		debug:                   debug,
 	}
 	bs.pacer = common.NewPacer(func() congestion.ByteCount {
 		return congestion.ByteCount(float64(bs.bps) / bs.ackRate)
@@ -127,6 +130,10 @@ func (b *BrutalSender) SetMaxDatagramSize(size congestion.ByteCount) {
 }

 func (b *BrutalSender) updateAckRate(currentTimestamp int64) {
+	if b.disableLossCompensation {
+		b.ackRate = 1
+		return
+	}
 	minTimestamp := currentTimestamp - pktInfoSlotCount
 	var ackCount, lossCount uint64
 	for _, info := range b.pktInfoSlots {
@@ -0,0 +1,45 @@
+package brutal
+
+import (
+	"testing"
+	"time"
+
+	"github.com/apernet/quic-go/congestion"
+	"github.com/apernet/quic-go/monotime"
+)
+
+// feedAckRate drives a single sampling slot with the given number of acked and
+// lost packets and returns the resulting ackRate.
+func feedAckRate(disableLossCompensation bool, ackCount, lossCount int) float64 {
+	b := NewBrutalSender(1000000, disableLossCompensation)
+	acked := make([]congestion.AckedPacketInfo, ackCount)
+	lost := make([]congestion.LostPacketInfo, lossCount)
+	// eventTime lands in a fixed slot; a single event carries enough samples.
+	b.OnCongestionEventEx(0, monotime.Time(5*time.Second), acked, lost)
+	return b.ackRate
+}
+
+func TestBrutalLossCompensation(t *testing.T) {
+	tests := []struct {
+		name      string
+		ack, loss int
+		want      float64 // expected ackRate when compensation is ENABLED
+	}{
+		{"no loss", 100, 0, 1.0},
+		{"20% loss", 80, 20, 0.8},
+		{"50% loss clamps to floor", 50, 50, minAckRate}, // 0.5 clamped up to 0.8
+		{"few samples stays 1", 10, 5, 1.0},              // below minSampleCount
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Compensation enabled (default behavior): ackRate reacts to loss.
+			if got := feedAckRate(false, tt.ack, tt.loss); got != tt.want {
+				t.Errorf("compensation on: ackRate = %v, want %v", got, tt.want)
+			}
+			// Compensation disabled: ackRate must stay pinned at 1 regardless.
+			if got := feedAckRate(true, tt.ack, tt.loss); got != 1.0 {
+				t.Errorf("compensation off: ackRate = %v, want 1.0", got)
+			}
+		})
+	}
+}
@@ -5,6 +5,7 @@ import (
 	"strings"

 	"github.com/apernet/quic-go"
+	"github.com/apernet/quic-go/congestion"
 	"github.com/xtls/xray-core/transport/internet/hysteria/congestion/bbr"
 	"github.com/xtls/xray-core/transport/internet/hysteria/congestion/brutal"
 )
@@ -36,13 +37,29 @@ func NormalizeBBRProfile(profile string) (string, error) {
 func UseBBR(conn *quic.Conn, profile bbr.Profile) {
 	conn.SetCongestionControl(bbr.NewBbrSender(
 		bbr.DefaultClock{},
-		bbr.GetInitialPacketSize(conn.RemoteAddr()),
+		seedPacketSize(conn.InitialPacketSize(), bbr.GetInitialPacketSize(conn.RemoteAddr())),
 		profile,
 	))
 }

-func UseBrutal(conn *quic.Conn, tx uint64) {
-	conn.SetCongestionControl(brutal.NewBrutalSender(tx))
+// seedPacketSize picks the datagram size to seed a replacement congestion
+// controller with, given the size QUIC itself starts at and the guess derived
+// from the remote address.
+//
+// The seed must not exceed what QUIC actually starts at. If it does, the first
+// path MTU probe can land between the two: QUIC sees an increase and reports
+// it, but the controller sees a decrease, which it cannot represent. Taking the
+// smaller of the two keeps the address-based guess as a floor for connections
+// whose path we can't reason about, while never seeding above QUIC.
+func seedPacketSize(quicSize, byAddr congestion.ByteCount) congestion.ByteCount {
+	if quicSize <= 0 {
+		return byAddr
+	}
+	return min(quicSize, byAddr)
+}
+
+func UseBrutal(conn *quic.Conn, tx uint64, disableLossCompensation bool) {
+	conn.SetCongestionControl(brutal.NewBrutalSender(tx, disableLossCompensation))
 }

 func UseConfigured(conn *quic.Conn, congestionType, bbrProfile string) {
@@ -90,6 +90,7 @@ func (c *client) dial(ctx context.Context) error {
 		MaxIdleTimeout:                 time.Duration(quicParams.MaxIdleTimeout) * time.Second,
 		KeepAlivePeriod:                time.Duration(quicParams.KeepAlivePeriod) * time.Second,
 		DisablePathMTUDiscovery:        quicParams.DisablePathMtuDiscovery || (runtime.GOOS != "linux" && runtime.GOOS != "windows" && runtime.GOOS != "darwin"),
+		ChromeParrot:                   !quicParams.DisableChromeParrot,
 		EnableDatagrams:                true,
 		MaxDatagramFrameSize:           MaxDatagramFrameSize,
 		OmitMaxDatagramFrameSize:       time.Now().After(time.Date(2026, 9, 1, 0, 0, 0, 0, time.UTC)),
@@ -172,7 +173,12 @@ func (c *client) dial(ctx context.Context) error {
 		pktConn = newConn
 	}

-	tr := &quic.Transport{Conn: pktConn}
+	tr := &quic.Transport{Conn: pktConn, DisableGSO: quicParams.DisableGSO}
+
+	if !quicParams.DisableChromeParrot {
+		tr.ConnectionIDGenerator = quic.ZeroLengthConnectionIDGenerator{}
+		c.tlsConfig.GetCertificate = nil
+	}

 	var conn *quic.Conn
 	rt := &http3.Transport{
@@ -219,6 +225,7 @@ func (c *client) dial(ctx context.Context) error {

 	// udp, _ := strconv.ParseBool(resp.Header.Get(ResponseHeaderUDPEnabled))
 	down, _ := strconv.ParseUint(resp.Header.Get(CommonHeaderCCRX), 10, 64)
+	errors.LogDebug(context.Background(), "ECHAccepted ", conn.ConnectionState().TLS.ECHAccepted)

 	switch quicParams.Congestion {
 	case "reno":
@@ -228,10 +235,10 @@ func (c *client) dial(ctx context.Context) error {
 		if quicParams.BrutalUp == 0 || down == 0 {
 			congestion.UseBBR(conn, bbr.Profile(quicParams.BbrProfile))
 		} else {
-			congestion.UseBrutal(conn, min(quicParams.BrutalUp, down))
+			congestion.UseBrutal(conn, min(quicParams.BrutalUp, down), quicParams.BrutalDisableLossCompensation)
 		}
 	case "force-brutal":
-		congestion.UseBrutal(conn, quicParams.BrutalUp)
+		congestion.UseBrutal(conn, quicParams.BrutalUp, quicParams.BrutalDisableLossCompensation)
 	default:
 		panic(quicParams.Congestion)
 	}
@@ -2,6 +2,7 @@ package hysteria

 import (
 	"context"
+	"crypto/rand"
 	gotls "crypto/tls"
 	"net/http"
 	"net/http/httputil"
@@ -78,10 +79,10 @@ func (h *httpHandler) AuthHTTP(w http.ResponseWriter, r *http.Request) bool {
 				if quicParams.BrutalUp == 0 || down == 0 {
 					congestion.UseBBR(conn, bbr.Profile(quicParams.BbrProfile))
 				} else {
-					congestion.UseBrutal(conn, min(quicParams.BrutalUp, down))
+					congestion.UseBrutal(conn, min(quicParams.BrutalUp, down), quicParams.BrutalDisableLossCompensation)
 				}
 			case "force-brutal":
-				congestion.UseBrutal(conn, quicParams.BrutalUp)
+				congestion.UseBrutal(conn, quicParams.BrutalUp, quicParams.BrutalDisableLossCompensation)
 			default:
 				panic(quicParams.Congestion)
 			}
@@ -165,8 +166,9 @@ func (l *Listener) handleClient(conn *quic.Conn) {
 		Handler:          handler,
 		StreamDispatcher: handler.StreamDispatcher,
 	}
-	_ = h3s.ServeQUICConn(conn)
+	err := h3s.ServeQUICConn(conn)
 	_ = conn.CloseWithError(closeErrCodeOK, "")
+	errors.LogDebug(context.Background(), conn.RemoteAddr(), " ServeQUICConn exited with ", err)
 }

 func (l *Listener) keepAccepting() {
@@ -219,21 +221,43 @@ func Listen(ctx context.Context, address net.Address, port net.Port, streamSetti
 			return nil, err
 		}
 		transport := http.DefaultTransport.(*http.Transport)
-		if config.MasqUrlInsecure {
-			transport = transport.Clone()
-			transport.TLSClientConfig = &gotls.Config{
-				InsecureSkipVerify: true,
+		switch u.Scheme {
+		case "http", "https":
+			if config.MasqUrlInsecure {
+				transport = transport.Clone()
+				if transport.TLSClientConfig == nil {
+					transport.TLSClientConfig = &gotls.Config{}
+				}
+				transport.TLSClientConfig.InsecureSkipVerify = true
 			}
+		case "", "unix":
+			u = &url.URL{Scheme: "http", Host: "localhost"}
+			path := u.Path
+			dialer := &net.Dialer{Timeout: 30 * time.Second}
+			transport = transport.Clone()
+			transport.Proxy = nil
+			transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
+				return dialer.DialContext(ctx, "unix", path)
+			}
+			transport.MaxIdleConns = masqueradeProxyMaxIdleConnections
+			transport.MaxIdleConnsPerHost = masqueradeProxyMaxIdleConnsPerHost
+		default:
+			return nil, errors.New("unknown scheme")
 		}
 		masqHandler = &httputil.ReverseProxy{
-			Rewrite: func(pr *httputil.ProxyRequest) {
-				pr.SetURL(u)
+			Rewrite: func(r *httputil.ProxyRequest) {
+				r.SetURL(u)
 				if !config.MasqUrlRewriteHost {
-					pr.Out.Host = pr.In.Host
+					r.Out.Host = r.In.Host
+				}
+				if config.MasqUrlXForwarded {
+					r.SetXForwarded()
 				}
 			},
-			Transport: transport,
+			Transport:  transport,
+			BufferPool: newMasqueradeProxyBufferPool(),
 			ErrorHandler: func(w http.ResponseWriter, r *http.Request, err error) {
+				errors.LogErrorInner(context.Background(), err, "HTTP reverse proxy error")
 				w.WriteHeader(http.StatusBadGateway)
 			},
 		}
@@ -307,7 +331,13 @@ func Listen(ctx context.Context, address net.Address, port net.Port, streamSetti
 		pktConn = newConn
 	}

-	tr := &quic.Transport{Conn: pktConn}
+	var k *quic.StatelessResetKey
+	if !quicParams.DisableStatelessReset {
+		k = &quic.StatelessResetKey{}
+		common.Must2(rand.Read((*k)[:]))
+	}
+
+	tr := &quic.Transport{Conn: pktConn, DisableGSO: quicParams.DisableGSO, StatelessResetKey: k}

 	listener, err := tr.Listen(tlsConfig.GetTLSConfig(tls.WithNextProto("h3")), quicConfig)
 	if err != nil {
@@ -336,3 +366,34 @@ func Listen(ctx context.Context, address net.Address, port net.Port, streamSetti
 func init() {
 	common.Must(internet.RegisterTransportListener(protocolName, Listen))
 }
+
+const (
+	masqueradeProxyBufferSize          = 32 * 1024
+	masqueradeProxyMaxIdleConnections  = 100
+	masqueradeProxyMaxIdleConnsPerHost = 32
+)
+
+type masqueradeProxyBufferPool struct {
+	pool sync.Pool
+}
+
+func newMasqueradeProxyBufferPool() *masqueradeProxyBufferPool {
+	return &masqueradeProxyBufferPool{
+		pool: sync.Pool{
+			New: func() any {
+				return make([]byte, masqueradeProxyBufferSize)
+			},
+		},
+	}
+}
+
+func (p *masqueradeProxyBufferPool) Get() []byte {
+	return p.pool.Get().([]byte)
+}
+
+func (p *masqueradeProxyBufferPool) Put(buf []byte) {
+	if cap(buf) < masqueradeProxyBufferSize {
+		return
+	}
+	p.pool.Put(buf[:masqueradeProxyBufferSize])
+}
@@ -175,6 +175,7 @@ func createHTTPClient(dest net.Destination, streamSettings *internet.MemoryStrea
 			KeepAlivePeriod:                time.Duration(quicParams.KeepAlivePeriod) * time.Second,
 			MaxIncomingStreams:             quicParams.MaxIncomingStreams,
 			DisablePathMTUDiscovery:        quicParams.DisablePathMtuDiscovery || (runtime.GOOS != "linux" && runtime.GOOS != "windows" && runtime.GOOS != "darwin"),
+			ChromeParrot:                   !quicParams.DisableChromeParrot,
 		}
 		if quicParams.MaxIdleTimeout == 0 {
 			quicConfig.MaxIdleTimeout = net.ConnIdleTimeout
@@ -255,18 +256,25 @@ func createHTTPClient(dest net.Destination, streamSettings *internet.MemoryStrea
 					pktConn = newConn
 				}

-				conn, err := quic.DialEarly(ctx, pktConn, udpAddr, tlsCfg, cfg)
+				tr := &quic.Transport{Conn: pktConn, DisableGSO: quicParams.DisableGSO}
+
+				if !quicParams.DisableChromeParrot {
+					tr.ConnectionIDGenerator = quic.ZeroLengthConnectionIDGenerator{}
+					tlsCfg.GetCertificate = nil
+				}
+
+				conn, err := tr.DialEarly(ctx, udpAddr, tlsCfg, cfg)
 				if err != nil {
 					return nil, err
 				}
-				context.AfterFunc(conn.Context(), func() { pktConn.Close() })
+				context.AfterFunc(conn.Context(), func() { tr.Close(); pktConn.Close() })

 				switch quicParams.Congestion {
 				case "reno":
 				case "", "bbr":
 					congestion.UseBBR(conn, bbr.Profile(quicParams.BbrProfile))
 				case "force-brutal":
-					congestion.UseBrutal(conn, quicParams.BrutalUp)
+					congestion.UseBrutal(conn, quicParams.BrutalUp, quicParams.BrutalDisableLossCompensation)
 				default:
 					panic(quicParams.Congestion)
 				}
@@ -3,6 +3,7 @@ package splithttp
 import (
 	"bytes"
 	"context"
+	"crypto/rand"
 	gotls "crypto/tls"
 	"encoding/base64"
 	"fmt"
@@ -506,7 +507,15 @@ func ListenXH(ctx context.Context, address net.Address, port net.Port, streamSet
 			DisablePathMTUDiscovery:        quicParams.DisablePathMtuDiscovery || (runtime.GOOS != "linux" && runtime.GOOS != "windows" && runtime.GOOS != "darwin"),
 		}

-		l.h3listener, err = quic.ListenEarly(Conn, tlsConfig, quicConfig)
+		var k *quic.StatelessResetKey
+		if !quicParams.DisableStatelessReset {
+			k = &quic.StatelessResetKey{}
+			common.Must2(rand.Read((*k)[:]))
+		}
+
+		tr := &quic.Transport{Conn: Conn, DisableGSO: quicParams.DisableGSO, StatelessResetKey: k}
+
+		l.h3listener, err = tr.ListenEarly(tlsConfig, quicConfig)
 		if err != nil {
 			return nil, errors.New("failed to listen QUIC for XHTTP/3 on ", address, ":", port).Base(err)
 		}
@@ -525,6 +534,8 @@ func ListenXH(ctx context.Context, address net.Address, port net.Port, streamSet
 			if err := l.h3server.ServeListener(l.h3listener); err != nil {
 				errors.LogErrorInner(ctx, err, "failed to serve HTTP/3 for XHTTP/3")
 			}
+			_ = tr.Close()
+			_ = Conn.Close()
 		}()
 	} else { // tcp
 		l.listener, err = internet.ListenSystem(ctx, &net.TCPAddr{
@@ -622,7 +633,7 @@ func (l *QListener) Accept(ctx context.Context) (*quic.Conn, error) {
 	case "", "bbr":
 		congestion.UseBBR(conn, bbr.Profile(l.quicParams.BbrProfile))
 	case "force-brutal":
-		congestion.UseBrutal(conn, l.quicParams.BrutalUp)
+		congestion.UseBrutal(conn, l.quicParams.BrutalUp, l.quicParams.BrutalDisableLossCompensation)
 	default:
 		panic(l.quicParams.Congestion)
 	}
@@ -50,18 +50,24 @@ func (d *DefaultSystemDialer) Dial(ctx context.Context, src net.Address, dest ne
 	errors.LogDebug(ctx, "dialing to "+dest.String())

 	if dest.Network == net.Network_UDP {
-		srcAddr := resolveSrcAddr(net.Network_UDP, src)
-		if srcAddr == nil {
-			srcAddr = &net.UDPAddr{
-				IP:   []byte{0, 0, 0, 0},
-				Port: 0,
-			}
-		}
-		var lc net.ListenConfig
 		destAddr, err := net.ResolveUDPAddr("udp", dest.NetAddr())
 		if err != nil {
 			return nil, err
 		}
+		srcAddr := resolveSrcAddr(net.Network_UDP, src)
+		if srcAddr == nil {
+			// some OS don't support mapped IPv4 dual stack
+			// and need to select 0.0.0.0 or [::] manually based on the destination
+			wildcard := net.AnyIP.IP()
+			if destAddr.IP.To4() == nil {
+				wildcard = net.AnyIPv6.IP()
+			}
+			srcAddr = &net.UDPAddr{
+				IP:   wildcard,
+				Port: 0,
+			}
+		}
+		var lc net.ListenConfig
 		lc.Control = func(network, address string, c syscall.RawConn) error {
 			for _, ctl := range Controllers {
 				if err := ctl(network, address, c); err != nil {