feat: TLS 1.3 mimicry obfuscation, multi-mode (auto + plain), session recreation

- tlsmimic: wrap QUIC packets in TLS 1.3 record headers - multi: auto-detect Salamander/TLS-mimic/plain on the same port - multi: random padding and jitter support for DPI evasion - reconnect: periodic session recreation via MaxSessionDuration - client/server: wire tlsmimic/auto/plain obfs types and config - NEW_FEATURES: translated to English
2026-06-17 16:36:29 +03:00 · 2026-06-17 16:36:29 +03:00 · 1e77bbe7b7
commit 1e77bbe7b7
parent da8366eb8a
9 changed files with 924 additions and 72 deletions
--- a/NEW_FEATURES.md
+++ b/NEW_FEATURES.md
@ -1,10 +1,10 @@
-# Новые возможности (относительно upstream)
+# New Features (vs upstream)

-## 1. L3 VPN туннель (Network)
+## 1. L3 VPN Tunnel (Network)

-Полноценный IP-туннель поверх QUIC. На сервере создаётся TUN-интерфейс, клиенты получают IP из пула, весь L3-трафик маршрутизируется через зашифрованное QUIC-соединение.
+Full IP tunnel over QUIC. A TUN interface is created on the server, clients get an IP from a pool, and all L3 traffic is routed through the encrypted QUIC connection.

-### Конфиг сервера (config.json)
+### Server config (config.json)

 ```json
 {
@ -21,15 +21,15 @@
 }
 ```

-Параметры:
- `enabled` — включить туннель
- `listen` — адрес для QUIC-слушателя (по умолч. `:5199`)
- `token` — общий секрет для аутентификации клиентов
- `tun.name` — имя TUN-интерфейса на сервере
- `tun.mtu` — MTU TUN-интерфейса
- `pool` — CIDR подсеть для выдачи IP клиентам
+Parameters:
+- `enabled` — enable the tunnel
+- `listen` — QUIC listener address (default `:5199`)
+- `token` — shared secret for client authentication
+- `tun.name` — TUN interface name on the server
+- `tun.mtu` — TUN interface MTU
+- `pool` — CIDR subnet for assigning IPs to clients

-### Конфиг клиента (client.json)
+### Client config (client.json)

 ```json
 {
@ -44,19 +44,19 @@
 }
 ```

-Параметры:
- `server` — адрес сервера (обязательно)
- `token` — общий секрет (должен совпадать с серверным)
- `tun.name` — имя TUN-интерфейса на клиенте
- `tun.mtu` — MTU TUN-интерфейса
+Parameters:
+- `server` — server address (required)
+- `token` — shared secret (must match the server)
+- `tun.name` — TUN interface name on the client
+- `tun.mtu` — TUN interface MTU

 ---

-## 2. FileMask шум (Noise)
+## 2. FileMask Noise

-Новый слой обфускации, который маскирует трафик под скачивание зашифрованных файлов. Работает поверх существующей обфускации (Salamander/Gecko). Сервер шлёт клиенту случайные куски реальных файлов с диска, имитируя активную загрузку.
+New obfuscation layer that masks traffic as downloading encrypted files. It works on top of the existing obfuscation (Salamander/Gecko). The server sends the client random chunks of real files from disk, simulating an active download.

-### Конфиг сервера
+### Server config

 ```json
 {
@ -73,23 +73,23 @@
 }
 ```

-Параметры:
- `type` — `"filemask"` для включения; `"none"` или пустое значение — отключено
- `filemask.dir` — **обязательно**, директория с файлами, содержимым которых будет маскироваться трафик
- `filemask.maxRate` — максимальная скорость шума (по умолч. `"512 kbps"`)
- `filemask.minPacketSize` — минимальный размер пакета шума
- `filemask.maxPacketSize` — максимальный размер пакета шума
- `filemask.idleThreshold` — таймаут бездействия клиента, после которого начинает генерироваться шум
+Parameters:
+- `type` — `"filemask"` to enable; `"none"` or empty to disable
+- `filemask.dir` — **required**, directory containing files used to mask traffic
+- `filemask.maxRate` — max noise rate (default `"512 kbps"`)
+- `filemask.minPacketSize` — minimum noise packet size
+- `filemask.maxPacketSize` — maximum noise packet size
+- `filemask.idleThreshold` — client idle timeout before noise generation starts

-Файлы из указанной директории шифруются AES-GCM на лету и отправляются клиенту.
+Files from the specified directory are encrypted with AES-GCM on the fly and sent to the client.

 ---

 ## 3. Hysteria Outbound

-Возможность использовать другой Hysteria сервер как upstream/выходной узел (outbound). Позволяет строить цепочки: клиент -> сервер А -> сервер Б (через hysteria outbound).
+Ability to use another Hysteria server as an upstream/outbound node. Allows building chains: client -> server A -> server B (via hysteria outbound).

-### Конфиг сервера
+### Server config

 ```json
 {
@ -141,15 +141,15 @@
 }
 ```

-Поддерживаемые параметры внутри `hysteria`:
- `server` — адрес целевого Hysteria сервера (обязательно)
- `auth` — пароль аутентификации (обязательно)
- `tls` — TLS настройки (SNI, insecure, pinSHA256, CA)
- `quic` — настройки QUIC (окна приёма, таймауты)
- `bandwidth` — лимиты пропускной способности
- `congestion` — алгоритм контроля перегрузки (bbr/cubic/brutal)
- `obfs` — обфускация для соединения с upstream (salamander/gecko)
- `transport` — транспорт (udp, с опциональным port hopping)
- `fastOpen` — включить fast open
+Supported parameters inside `hysteria`:
+- `server` — target Hysteria server address (required)
+- `auth` — authentication password (required)
+- `tls` — TLS settings (SNI, insecure, pinSHA256, CA)
+- `quic` — QUIC settings (receive windows, timeouts)
+- `bandwidth` — bandwidth limits
+- `congestion` — congestion control algorithm (bbr/cubic/brutal)
+- `obfs` — obfuscation for the upstream connection (salamander/gecko)
+- `transport` — transport (udp, with optional port hopping)
+- `fastOpen` — enable fast open

-Используется в разделе `outbounds` наравне с `direct`, `socks5`, `http`.
+Used in the `outbounds` section alongside `direct`, `socks5`, `http`.
--- a/app/cmd/client.go
+++ b/app/cmd/client.go
@ -82,6 +82,7 @@ type clientConfig struct {
 	Bandwidth     clientConfigBandwidth  `mapstructure:"bandwidth"`
 	FastOpen              bool                   `mapstructure:"fastOpen"`
 	Lazy                  bool                   `mapstructure:"lazy"`
+	MaxSessionDuration    time.Duration          `mapstructure:"maxSessionDuration"`
 	SOCKS5                *socks5Config          `mapstructure:"socks5"`
 	HTTP          *httpConfig            `mapstructure:"http"`
 	TCPForwarding []tcpForwardingEntry   `mapstructure:"tcpForwarding"`
@ -136,10 +137,15 @@ type clientConfigObfsGecko struct {
 	MaxPacketSize int    `mapstructure:"maxPacketSize"`
 }

+type clientConfigObfsTLSMimic struct {
+	Password string `mapstructure:"password"`
+}
+
 type clientConfigObfs struct {
 	Type       string                     `mapstructure:"type"`
 	Salamander clientConfigObfsSalamander `mapstructure:"salamander"`
 	Gecko      clientConfigObfsGecko      `mapstructure:"gecko"`
+	TLSMimic   clientConfigObfsTLSMimic   `mapstructure:"tlsmimic"`
 }

 type clientConfigTLS struct {
@ -349,6 +355,12 @@ func (c *clientConfig) wrapObfs(conn net.PacketConn) (net.PacketConn, error) {
 			return nil, configError{Field: "obfs.gecko", Err: err}
 		}
 		return wrapped, nil
+	case "tlsmimic":
+		wrapped, err := obfs.WrapPacketConnTLSMimic(conn, []byte(c.Obfs.TLSMimic.Password))
+		if err != nil {
+			return nil, configError{Field: "obfs.tlsmimic.password", Err: err}
+		}
+		return wrapped, nil
 	default:
 		return nil, configError{Field: "obfs.type", Err: errors.New("unsupported obfuscation type")}
 	}
@ -506,6 +518,9 @@ func (c *clientConfig) URI() string {
 	case "gecko":
 		q.Set("obfs", "gecko")
 		q.Set("obfs-password", c.Obfs.Gecko.Password)
+	case "tlsmimic":
+		q.Set("obfs", "tlsmimic")
+		q.Set("obfs-password", c.Obfs.TLSMimic.Password)
 	}
 	if c.TLS.SNI != "" {
 		q.Set("sni", c.TLS.SNI)
@ -565,6 +580,8 @@ func (c *clientConfig) parseURI() bool {
 			c.Obfs.Salamander.Password = q.Get("obfs-password")
 		case "gecko":
 			c.Obfs.Gecko.Password = q.Get("obfs-password")
+		case "tlsmimic":
+			c.Obfs.TLSMimic.Password = q.Get("obfs-password")
 		}
 	}
 	if sni := q.Get("sni"); sni != "" {
@ -805,7 +822,7 @@ func runClient(v *viper.Viper) {
 		logger.Fatal("failed to parse client config", zap.Error(err))
 	}

-	c, err := client.NewReconnectableClient(
+	c, err := client.NewReconnectableClientWithMaxSession(
 		config.Config,
 		func(c client.Client, info *client.HandshakeInfo, count int) {
 			connectLog(info, count)
@ -816,7 +833,7 @@ func runClient(v *viper.Viper) {
 			if count == 1 && !disableUpdateCheck {
 				go runCheckUpdateClient(c)
 			}
-		}, config.Lazy,
+		}, config.Lazy, config.MaxSessionDuration,
 	)
 	if err != nil {
 		logger.Fatal("failed to initialize client", zap.Error(err))
--- a/app/cmd/server.go
+++ b/app/cmd/server.go
@ -109,10 +109,17 @@ type serverConfigObfsGecko struct {
 	MaxPacketSize int    `mapstructure:"maxPacketSize"`
 }

+type serverConfigObfsTLSMimic struct {
+	Password string `mapstructure:"password"`
+}
+
 type serverConfigObfs struct {
 	Type              string                     `mapstructure:"type"`
 	Salamander        serverConfigObfsSalamander `mapstructure:"salamander"`
 	Gecko             serverConfigObfsGecko      `mapstructure:"gecko"`
+	TLSMimic          serverConfigObfsTLSMimic   `mapstructure:"tlsmimic"`
+	MinPadding        int                        `mapstructure:"minPadding"`
+	MaxPadding        int                        `mapstructure:"maxPadding"`
 }

 type serverConfigNoiseFileMask struct {
@ -471,6 +478,26 @@ func (c *serverConfig) wrapObfs(conn net.PacketConn) (net.PacketConn, error) {
 			return nil, configError{Field: "obfs.gecko", Err: err}
 		}
 		packetConn = wrapped
+	case "tlsmimic":
+		wrapped, err := obfs.WrapPacketConnTLSMimic(packetConn, []byte(c.Obfs.TLSMimic.Password))
+		if err != nil {
+			return nil, configError{Field: "obfs.tlsmimic.password", Err: err}
+		}
+		packetConn = wrapped
+	case "auto", "salamander+tlsmimic":
+		psk := c.Obfs.Salamander.Password
+		if psk == "" {
+			psk = c.Obfs.TLSMimic.Password
+		}
+		wrapped, err := obfs.WrapPacketConnMulti(packetConn, obfs.MultiObfsOptions{
+			Password:   psk,
+			MinPadding: c.Obfs.MinPadding,
+			MaxPadding: c.Obfs.MaxPadding,
+		})
+		if err != nil {
+			return nil, configError{Field: "obfs.multi", Err: err}
+		}
+		packetConn = wrapped
 	default:
 		return nil, configError{Field: "obfs.type", Err: errors.New("unsupported obfuscation type")}
 	}
@ -1339,6 +1366,8 @@ func serverConfigOutboundHysteriaToOutbound(c serverConfigOutboundHysteria) (out
 		obfsPassword = c.Obfs.Salamander.Password
 	case "gecko":
 		obfsPassword = c.Obfs.Gecko.Password
+	case "tlsmimic":
+		obfsPassword = c.Obfs.TLSMimic.Password
 	}
 	cfg := &outbounds.HysteriaOutboundConfig{
 		ServerAddr:      c.Server,
--- a/core/client/reconnect.go
+++ b/core/client/reconnect.go
@ -3,19 +3,25 @@ package client
 import (
 	"net"
 	"sync"
+	"time"

 	coreErrs "github.com/apernet/hysteria/core/v2/errors"
 )

-// reconnectableClientImpl is a wrapper of Client, which can reconnect when the connection is closed,
-// except when the caller explicitly calls Close() to permanently close this client.
+// reconnectableClientImpl is a wrapper of Client, which can reconnect when
+// the connection is closed (except when the caller explicitly calls Close()),
+// or periodically when maxSessionDuration > 0 to avoid long-lived sessions.
 type reconnectableClientImpl struct {
-	configFunc    func() (*Config, error)           // called before connecting
-	connectedFunc func(Client, *HandshakeInfo, int) // called when successfully connected
+	configFunc         func() (*Config, error)
+	connectedFunc      func(Client, *HandshakeInfo, int)
 	client             Client
 	count              int
+	maxSessionDuration time.Duration
+
 	m             sync.Mutex
-	closed        bool // permanent close
+	closed        bool
+	recreateTimer *time.Timer
+	recreateStop  chan struct{}
 }

 // NewReconnectableClient creates a reconnectable client.
@ -23,36 +29,100 @@ type reconnectableClientImpl struct {
 // We use a function for config mainly to delay config evaluation
 // (which involves DNS resolution) until the actual connection attempt.
 func NewReconnectableClient(configFunc func() (*Config, error), connectedFunc func(Client, *HandshakeInfo, int), lazy bool) (Client, error) {
+	return NewReconnectableClientWithMaxSession(configFunc, connectedFunc, lazy, 0)
+}
+
+// NewReconnectableClientWithMaxSession creates a reconnectable client that
+// periodically reconnects every maxSessionDuration to avoid long-lived
+// sessions being detected by DPI. Set to 0 to disable timed recreation.
+func NewReconnectableClientWithMaxSession(configFunc func() (*Config, error), connectedFunc func(Client, *HandshakeInfo, int), lazy bool, maxSessionDuration time.Duration) (Client, error) {
 	rc := &reconnectableClientImpl{
 		configFunc:         configFunc,
 		connectedFunc:      connectedFunc,
+		maxSessionDuration: maxSessionDuration,
+		recreateStop:       make(chan struct{}),
 	}
 	if !lazy {
 		if err := rc.reconnect(); err != nil {
 			return nil, err
 		}
 	}
+	go rc.recreateLoop()
 	return rc, nil
 }

-func (rc *reconnectableClientImpl) reconnect() error {
-	if rc.client != nil {
-		_ = rc.client.Close()
+func (rc *reconnectableClientImpl) recreateLoop() {
+	for {
+		rc.m.Lock()
+		if rc.closed {
+			rc.m.Unlock()
+			return
 		}
-	var info *HandshakeInfo
+		timer := rc.recreateTimer
+		rc.m.Unlock()
+		if timer == nil {
+			// No timer configured, sleep until close
+			<-rc.recreateStop
+			return
+		}
+		select {
+		case <-timer.C:
+			_ = rc.reconnect()
+		case <-rc.recreateStop:
+			timer.Stop()
+			return
+		}
+	}
+}
+
+func (rc *reconnectableClientImpl) reconnect() error {
+	rc.m.Lock()
+	if rc.closed {
+		rc.m.Unlock()
+		return coreErrs.ClosedError{}
+	}
+	oldClient := rc.client
+	rc.client = nil
+	rc.m.Unlock()
+
+	if oldClient != nil {
+		_ = oldClient.Close()
+	}
+
 	config, err := rc.configFunc()
 	if err != nil {
 		return err
 	}
-	rc.client, info, err = NewClient(config)
+	client, info, err := NewClient(config)
 	if err != nil {
 		return err
-	} else {
+	}
+
+	rc.m.Lock()
+	if rc.closed {
+		_ = client.Close()
+		rc.m.Unlock()
+		return coreErrs.ClosedError{}
+	}
+	rc.client = client
 	rc.count++
-		if rc.connectedFunc != nil {
-			rc.connectedFunc(rc, info, rc.count)
+	rc.resetRecreateTimerLocked()
+	connectedFunc := rc.connectedFunc
+	rc.m.Unlock()
+
+	if connectedFunc != nil {
+		connectedFunc(rc, info, rc.count)
 	}
 	return nil
+}
+
+func (rc *reconnectableClientImpl) resetRecreateTimerLocked() {
+	if rc.recreateTimer != nil {
+		rc.recreateTimer.Stop()
+		rc.recreateTimer = nil
+	}
+	if rc.maxSessionDuration > 0 {
+		rc.recreateTimer = time.NewTimer(rc.maxSessionDuration)
 	}
 }

@ -111,10 +181,16 @@ func (rc *reconnectableClientImpl) UDP() (HyUDPConn, error) {

 func (rc *reconnectableClientImpl) Close() error {
 	rc.m.Lock()
-	defer rc.m.Unlock()
 	rc.closed = true
-	if rc.client != nil {
-		return rc.client.Close()
+	if rc.recreateTimer != nil {
+		rc.recreateTimer.Stop()
+		rc.recreateTimer = nil
+	}
+	close(rc.recreateStop)
+	client := rc.client
+	rc.m.Unlock()
+	if client != nil {
+		return client.Close()
 	}
 	return nil
 }
--- a/extras/obfs/multi.go
+++ b/extras/obfs/multi.go
@ -0,0 +1,303 @@
+package obfs
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"net"
+	"sync"
+	"syscall"
+	"time"
+)
+
+// ObfsMode represents an obfuscation method.
+type ObfsMode int
+
+const (
+	ObfsModeSalamander ObfsMode = iota
+	ObfsModeTLSMimic
+	ObfsModePlain
+)
+
+// MultiObfsOptions configures the multi-mode obfuscation wrapper.
+type MultiObfsOptions struct {
+	// PSK for Salamander and TLS-mimic (they share the same key).
+	Password string
+	// PadRnd randomizes each outbound packet's total size to land in
+	// [MinPadding, MaxPadding]. Zero means no padding.
+	MinPadding int
+	MaxPadding int
+	// SendJitter adds a random delay [0, SendJitter) before each outbound
+	// packet to break constant-bitrate DPI patterns. Zero means no delay.
+	SendJitter time.Duration
+}
+
+type multiObfsPacketConn struct {
+	inner net.PacketConn
+
+	sm          *salamanderObfuscator
+	tm          *tlsMimicObfuscator
+	pad         bool
+	minP, maxP  int
+	sendJitter  time.Duration
+
+	addrModes map[string]ObfsMode
+	mu        sync.RWMutex
+
+	readMu  sync.Mutex
+	readBuf []byte
+	writeMu sync.Mutex
+	writeBuf []byte
+
+	closeCh   chan struct{}
+	closeOnce sync.Once
+}
+
+// WrapPacketConnMulti wraps conn so it accepts packets obfuscated with any of
+// Salamander or TLS-mimic on the same port. Which method to use for outbound
+// packets is auto-detected per remote address on the first inbound packet from
+// that address.
+//
+// Both Salamander and TLS-mimic use the same PSK for the BLAKE2b-XOR cipher.
+func WrapPacketConnMulti(conn net.PacketConn, opts MultiObfsOptions) (net.PacketConn, error) {
+	m := &multiObfsPacketConn{
+		inner:       conn,
+		addrModes:   make(map[string]ObfsMode),
+		readBuf:     make([]byte, udpBufferSize),
+		writeBuf:    make([]byte, udpBufferSize),
+		sendJitter:  opts.SendJitter,
+		closeCh:     make(chan struct{}),
+	}
+
+	if opts.Password != "" {
+		psk := []byte(opts.Password)
+		var err error
+		m.sm, err = newSalamanderObfuscator(psk)
+		if err != nil {
+			return nil, err
+		}
+		m.tm, err = newTLSMimicObfuscator(psk)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if opts.MinPadding > 0 && opts.MaxPadding >= opts.MinPadding {
+		m.pad = true
+		m.minP = opts.MinPadding
+		m.maxP = opts.MaxPadding
+	}
+
+	return m, nil
+}
+
+// --- Read path: try each deobfuscator in order, cache the method ---
+
+func (m *multiObfsPacketConn) ReadFrom(p []byte) (int, net.Addr, error) {
+	for {
+		select {
+		case <-m.closeCh:
+			return 0, nil, net.ErrClosed
+		default:
+		}
+
+		m.readMu.Lock()
+		n, addr, err := m.inner.ReadFrom(m.readBuf)
+		if err != nil {
+			m.readMu.Unlock()
+			return 0, addr, err
+		}
+		if n <= 0 {
+			m.readMu.Unlock()
+			continue
+		}
+
+		data := m.readBuf[:n]
+		var plaintext []byte
+		var mode ObfsMode
+
+		// 1. Try TLS-mimic (detectable by leading 0x17 on the wire)
+		if m.tm != nil && n > 0 && data[0] == 0x17 {
+			buf := make([]byte, udpBufferSize)
+			nn := m.tm.Deobfuscate(data, buf)
+			if nn > 0 {
+				plaintext = buf[:nn]
+				mode = ObfsModeTLSMimic
+			}
+		}
+
+		// 2. Plain QUIC pass-through (QUIC long header: first two bits = 11)
+		if plaintext == nil && n > 0 && data[0]&0xC0 == 0xC0 {
+			buf := make([]byte, n)
+			copy(buf, data)
+			plaintext = buf
+			mode = ObfsModePlain
+		}
+
+		// 3. Try Salamander
+		if plaintext == nil && m.sm != nil {
+			buf := make([]byte, udpBufferSize)
+			nn := m.sm.Deobfuscate(data, buf)
+			if nn > 0 {
+				plaintext = buf[:nn]
+				mode = ObfsModeSalamander
+			}
+		}
+
+		// If no method worked, drop the packet.
+		if plaintext == nil {
+			m.readMu.Unlock()
+			continue
+		}
+
+		// Cache the method for this source address
+		if addr != nil {
+			m.mu.Lock()
+			m.addrModes[addr.String()] = mode
+			m.mu.Unlock()
+		}
+
+		nn := copy(p, plaintext)
+		m.readMu.Unlock()
+		return nn, addr, nil
+	}
+}
+
+// --- Write path: use cached method, default to Salamander ---
+
+func (m *multiObfsPacketConn) WriteTo(p []byte, addr net.Addr) (int, error) {
+	mode := m.lookupMode(addr)
+
+	m.writeMu.Lock()
+	defer m.writeMu.Unlock()
+
+	var wire []byte
+	switch mode {
+	case ObfsModeTLSMimic:
+		if m.tm == nil {
+			return 0, net.ErrClosed
+		}
+		nn := m.tm.Obfuscate(p, m.writeBuf)
+		wire = m.writeBuf[:nn]
+	case ObfsModeSalamander:
+		if m.sm == nil {
+			return 0, net.ErrClosed
+		}
+		nn := m.sm.Obfuscate(p, m.writeBuf)
+		wire = m.writeBuf[:nn]
+	case ObfsModePlain:
+		wire = p
+	default:
+		wire = p
+		if m.sm != nil {
+			nn := m.sm.Obfuscate(p, m.writeBuf)
+			wire = m.writeBuf[:nn]
+		}
+	}
+
+	if m.pad {
+		wire = m.maybePad(wire)
+	}
+
+	if m.sendJitter > 0 {
+		time.Sleep(Jitter(m.sendJitter))
+	}
+
+	_, err := m.inner.WriteTo(wire, addr)
+	if err != nil {
+		return 0, err
+	}
+	return len(p), nil
+}
+
+func (m *multiObfsPacketConn) lookupMode(addr net.Addr) ObfsMode {
+	if addr == nil {
+		return ObfsModeSalamander
+	}
+	m.mu.RLock()
+	mode, ok := m.addrModes[addr.String()]
+	m.mu.RUnlock()
+	if ok {
+		return mode
+	}
+	// Unknown address. For servers, this shouldn't happen in practice
+	// because the server receives a packet before sending one.
+	return ObfsModeSalamander
+}
+
+// maybePad appends random padding so the total packet length falls in
+// [minP, maxP]. Does nothing if padding is disabled or the packet already
+// exceeds maxP.
+func (m *multiObfsPacketConn) maybePad(wire []byte) []byte {
+	base := len(wire)
+	if base >= m.maxP {
+		return wire
+	}
+	// pick a target between [max(base, minP), maxP]
+	target := base
+	if m.maxP > base {
+		// random in [max(base, minP), maxP]
+		lo := base
+		if m.minP > lo {
+			lo = m.minP
+		}
+		if lo <= m.maxP {
+			target = lo + randIntn(m.maxP-lo+1)
+		}
+	}
+	if target <= base {
+		return wire
+	}
+	out := make([]byte, target)
+	copy(out, wire)
+	_, _ = rand.Read(out[base:target])
+	return out
+}
+
+// --- net.PacketConn boilerplate ---
+
+func (m *multiObfsPacketConn) Close() error {
+	m.closeOnce.Do(func() { close(m.closeCh) })
+	return m.inner.Close()
+}
+
+func (m *multiObfsPacketConn) LocalAddr() net.Addr { return m.inner.LocalAddr() }
+
+func (m *multiObfsPacketConn) SetDeadline(t time.Time) error     { return m.inner.SetDeadline(t) }
+func (m *multiObfsPacketConn) SetReadDeadline(t time.Time) error { return m.inner.SetReadDeadline(t) }
+func (m *multiObfsPacketConn) SetWriteDeadline(t time.Time) error {
+	return m.inner.SetWriteDeadline(t)
+}
+
+func (m *multiObfsPacketConn) SyscallConn() (syscall.RawConn, error) {
+	if u, ok := m.inner.(udpLikePacketConn); ok {
+		return u.SyscallConn()
+	}
+	return nil, syscall.EOPNOTSUPP
+}
+
+func (m *multiObfsPacketConn) SetReadBuffer(bytes int) error {
+	if u, ok := m.inner.(udpLikePacketConn); ok {
+		return u.SetReadBuffer(bytes)
+	}
+	return syscall.EOPNOTSUPP
+}
+
+func (m *multiObfsPacketConn) SetWriteBuffer(bytes int) error {
+	if u, ok := m.inner.(udpLikePacketConn); ok {
+		return u.SetWriteBuffer(bytes)
+	}
+	return syscall.EOPNOTSUPP
+}
+
+// Jitter returns a random duration in [-maxJitter, +maxJitter].
+// If maxJitter is zero, returns 0 immediately.
+func Jitter(maxJitter time.Duration) time.Duration {
+	if maxJitter <= 0 {
+		return 0
+	}
+	var b [8]byte
+	_, _ = rand.Read(b[:])
+	f := float64(binary.BigEndian.Uint64(b[:])>>11) / (1 << 53)
+	j := time.Duration(f * float64(maxJitter*2))
+	return j - maxJitter
+}
--- a/extras/obfs/multi_test.go
+++ b/extras/obfs/multi_test.go
@ -0,0 +1,226 @@
+package obfs
+
+import (
+	"net"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// duplexPipe pairs two channels so that write(0→1) is read by read(1→0).
+type duplexPipe struct {
+	toServer chan pkt
+	toClient chan pkt
+	addr     net.Addr
+}
+
+type pkt struct {
+	data []byte
+	addr net.Addr
+}
+
+func newDuplexPipe() *duplexPipe {
+	return &duplexPipe{
+		toServer: make(chan pkt, 100),
+		toClient: make(chan pkt, 100),
+		addr:     &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 9999},
+	}
+}
+
+func (p *duplexPipe) ReadFromServerSide(b []byte) (int, net.Addr, error) {
+	pkt := <-p.toServer
+	return copy(b, pkt.data), pkt.addr, nil
+}
+
+func (p *duplexPipe) WriteToServerSide(b []byte, addr net.Addr) (int, error) {
+	data := make([]byte, len(b))
+	copy(data, b)
+	p.toClient <- pkt{data: data, addr: addr}
+	return len(b), nil
+}
+
+func (p *duplexPipe) ReadFromClientSide(b []byte) (int, net.Addr, error) {
+	pkt := <-p.toClient
+	return copy(b, pkt.data), pkt.addr, nil
+}
+
+func (p *duplexPipe) WriteToClientSide(b []byte, addr net.Addr) (int, error) {
+	data := make([]byte, len(b))
+	copy(data, b)
+	p.toServer <- pkt{data: data, addr: addr}
+	return len(b), nil
+}
+
+// serverConn wraps duplexPipe to look like a single PacketConn from the
+// server's perspective: ReadFrom reads client→server, WriteTo writes server→client.
+type serverConn struct {
+	p *duplexPipe
+}
+
+func (s *serverConn) ReadFrom(b []byte) (int, net.Addr, error)  { return s.p.ReadFromServerSide(b) }
+func (s *serverConn) WriteTo(b []byte, a net.Addr) (int, error) { return s.p.WriteToServerSide(b, a) }
+func (s *serverConn) Close() error                               { return nil }
+func (s *serverConn) LocalAddr() net.Addr                        { return s.p.addr }
+func (s *serverConn) SetDeadline(time.Time) error                { return nil }
+func (s *serverConn) SetReadDeadline(time.Time) error            { return nil }
+func (s *serverConn) SetWriteDeadline(time.Time) error           { return nil }
+
+// clientConn wraps duplexPipe from the client perspective.
+type clientConn struct {
+	p *duplexPipe
+}
+
+func (c *clientConn) ReadFrom(b []byte) (int, net.Addr, error)  { return c.p.ReadFromClientSide(b) }
+func (c *clientConn) WriteTo(b []byte, a net.Addr) (int, error) { return c.p.WriteToClientSide(b, a) }
+func (c *clientConn) Close() error                               { return nil }
+func (c *clientConn) LocalAddr() net.Addr                        { return c.p.addr }
+func (c *clientConn) SetDeadline(time.Time) error                { return nil }
+func (c *clientConn) SetReadDeadline(time.Time) error            { return nil }
+func (c *clientConn) SetWriteDeadline(time.Time) error           { return nil }
+
+func TestMultiObfsRoundTripSalamander(t *testing.T) {
+	d := newDuplexPipe()
+	server, err := WrapPacketConnMulti(&serverConn{d}, MultiObfsOptions{
+		Password: "test",
+	})
+	require.NoError(t, err)
+	defer server.Close()
+
+	client, err := WrapPacketConnSalamander(&clientConn{d}, []byte("test"))
+	require.NoError(t, err)
+
+	payload := []byte("hello salamander via multi")
+	n, err := client.WriteTo(payload, d.addr)
+	require.NoError(t, err)
+	require.Equal(t, len(payload), n)
+
+	buf := make([]byte, 2048)
+	n, addr, err := server.ReadFrom(buf)
+	require.NoError(t, err)
+	assert.Equal(t, payload, buf[:n])
+
+	_, err = server.WriteTo(buf[:n], addr)
+	require.NoError(t, err)
+
+	buf2 := make([]byte, 2048)
+	n, _, err = client.ReadFrom(buf2)
+	require.NoError(t, err)
+	assert.Equal(t, payload, buf2[:n])
+}
+
+func TestMultiObfsRoundTripTLSMimic(t *testing.T) {
+	d := newDuplexPipe()
+	server, err := WrapPacketConnMulti(&serverConn{d}, MultiObfsOptions{
+		Password: "test",
+	})
+	require.NoError(t, err)
+	defer server.Close()
+
+	client, err := WrapPacketConnTLSMimic(&clientConn{d}, []byte("test"))
+	require.NoError(t, err)
+
+	payload := []byte("hello tlsmimic via multi")
+	n, err := client.WriteTo(payload, d.addr)
+	require.NoError(t, err)
+	require.Equal(t, len(payload), n)
+
+	buf := make([]byte, 2048)
+	n, addr, err := server.ReadFrom(buf)
+	require.NoError(t, err)
+	assert.Equal(t, payload, buf[:n])
+
+	_, err = server.WriteTo(buf[:n], addr)
+	require.NoError(t, err)
+
+	buf2 := make([]byte, 2048)
+	n, _, err = client.ReadFrom(buf2)
+	require.NoError(t, err)
+	assert.Equal(t, payload, buf2[:n])
+}
+
+func TestMultiObfsRoundTripBoth(t *testing.T) {
+	d := newDuplexPipe()
+	server, err := WrapPacketConnMulti(&serverConn{d}, MultiObfsOptions{
+		Password: "test",
+	})
+	require.NoError(t, err)
+	defer server.Close()
+
+	payload1 := []byte("from salamander")
+	payload2 := []byte("from tlsmimic")
+
+	// Write obfuscated data directly to the server-side pipe channel
+	// using pre-computed obfuscated payloads.
+	sm, _ := newSalamanderObfuscator([]byte("test"))
+	tm, _ := newTLSMimicObfuscator([]byte("test"))
+
+	smOut := make([]byte, 2048)
+	tmOut := make([]byte, 2048)
+	smN := sm.Obfuscate(payload1, smOut)
+	tmN := tm.Obfuscate(payload2, tmOut)
+
+	// Both "clients" send through the shared pipe's client→server channel
+	d.toServer <- pkt{data: smOut[:smN], addr: &net.UDPAddr{IP: net.IPv4(10, 0, 0, 1), Port: 10001}}
+	d.toServer <- pkt{data: tmOut[:tmN], addr: &net.UDPAddr{IP: net.IPv4(10, 0, 0, 2), Port: 10002}}
+
+	buf := make([]byte, 2048)
+	n, addr1, err := server.ReadFrom(buf)
+	require.NoError(t, err)
+	assert.Equal(t, payload1, buf[:n])
+
+	n, addr2, err := server.ReadFrom(buf)
+	require.NoError(t, err)
+	assert.Equal(t, payload2, buf[:n])
+
+	// Server responds to each with the correct method (auto-detected)
+	_, err = server.WriteTo([]byte("reply1"), addr1)
+	require.NoError(t, err)
+	_, err = server.WriteTo([]byte("reply2"), addr2)
+	require.NoError(t, err)
+
+	// Read server responses from client side
+	rBuf := make([]byte, 2048)
+	n, _, err = d.ReadFromClientSide(rBuf)
+	require.NoError(t, err)
+	// First response to Salamander client
+	out := make([]byte, 2048)
+	nn := sm.Deobfuscate(rBuf[:n], out)
+	assert.Equal(t, []byte("reply1"), out[:nn])
+
+	n, _, err = d.ReadFromClientSide(rBuf)
+	require.NoError(t, err)
+	// Second response to TLS-mimic client
+	nn = tm.Deobfuscate(rBuf[:n], out)
+	assert.Equal(t, []byte("reply2"), out[:nn])
+}
+
+func TestMultiObfsRequiresPasswordForObfs(t *testing.T) {
+	d := newDuplexPipe()
+	_, err := WrapPacketConnMulti(&serverConn{d}, MultiObfsOptions{
+		Password: "",
+	})
+	assert.NoError(t, err)
+}
+
+func TestMultiObfsRandomPadding(t *testing.T) {
+	d := newDuplexPipe()
+	server, err := WrapPacketConnMulti(&serverConn{d}, MultiObfsOptions{
+		Password:   "test",
+		MinPadding: 1000,
+		MaxPadding: 1200,
+	})
+	require.NoError(t, err)
+	defer server.Close()
+
+	_, err = server.WriteTo([]byte("small"), d.addr)
+	require.NoError(t, err)
+
+	// Read raw from client side to check padding
+	buf := make([]byte, 2048)
+	n, _, err := d.ReadFromClientSide(buf)
+	require.NoError(t, err)
+	assert.GreaterOrEqual(t, n, 1000)
+	assert.LessOrEqual(t, n, 1200)
+}
--- a/extras/obfs/tlsmimic.go
+++ b/extras/obfs/tlsmimic.go
@ -0,0 +1,118 @@
+package obfs
+
+import (
+	"encoding/binary"
+	"fmt"
+	"math/rand"
+	"net"
+	"sync"
+	"time"
+
+	"golang.org/x/crypto/blake2b"
+)
+
+const (
+	tmPSKMinLen       = 4
+	tmSaltLen         = 8
+	tmKeyLen          = blake2b.Size256
+	tmHeaderSize      = 5 // TLS record header: content type(1) + version(2) + length(2)
+	tmContentTypeData = 0x17
+	tmVersionMajor    = 0x03
+	tmVersionMinor    = 0x03 // TLS 1.2 wire version (used in TLS 1.3 too)
+)
+
+var errTLSMimicPSKTooShort = fmt.Errorf("TLS mimic PSK must be at least %d bytes", tmPSKMinLen)
+
+// tlsMimicObfuscator encrypts each packet with BLAKE2b-256(PSK || salt) XOR
+// and wraps the result in a TLS 1.3 Application Data record header.
+// Wire format: [TLS record header (5 bytes)][salt (8 bytes)][XOR'd payload]
+type tlsMimicObfuscator struct {
+	PSK     []byte
+	RandSrc *rand.Rand
+
+	lk       sync.Mutex
+	keyInput []byte
+}
+
+func newTLSMimicObfuscator(psk []byte) (*tlsMimicObfuscator, error) {
+	if len(psk) < tmPSKMinLen {
+		return nil, errTLSMimicPSKTooShort
+	}
+	pskCopy := append([]byte(nil), psk...)
+	keyInput := make([]byte, len(pskCopy)+tmSaltLen)
+	copy(keyInput, pskCopy)
+	return &tlsMimicObfuscator{
+		PSK:      pskCopy,
+		RandSrc:  rand.New(rand.NewSource(time.Now().UnixNano())),
+		keyInput: keyInput,
+	}, nil
+}
+
+// WrapPacketConnTLSMimic wraps conn with TLS 1.3 mimicry obfuscation.
+// Every outbound packet is encrypted with BLAKE2b-256(PSK || random salt) XOR
+// and wrapped in a TLS record header, making the traffic appear as TLS.
+func WrapPacketConnTLSMimic(conn net.PacketConn, psk []byte) (net.PacketConn, error) {
+	ob, err := newTLSMimicObfuscator(psk)
+	if err != nil {
+		return nil, err
+	}
+	return wrapPacketConn(conn, ob), nil
+}
+
+func (o *tlsMimicObfuscator) Obfuscate(in, out []byte) int {
+	payloadLen := tmSaltLen + len(in)
+	outLen := tmHeaderSize + payloadLen
+	if len(out) < outLen {
+		return 0
+	}
+	// Generate random salt into position after TLS header
+	o.lk.Lock()
+	_, _ = o.RandSrc.Read(out[tmHeaderSize : tmHeaderSize+tmSaltLen])
+	key := o.keyLocked(out[tmHeaderSize : tmHeaderSize+tmSaltLen])
+	o.lk.Unlock()
+	// XOR encrypt payload
+	for i, c := range in {
+		out[tmHeaderSize+tmSaltLen+i] = c ^ key[i%tmKeyLen]
+	}
+	// TLS record header
+	out[0] = tmContentTypeData
+	out[1] = tmVersionMajor
+	out[2] = tmVersionMinor
+	binary.BigEndian.PutUint16(out[3:5], uint16(payloadLen))
+	return outLen
+}
+
+func (o *tlsMimicObfuscator) Deobfuscate(in, out []byte) int {
+	if len(in) < tmHeaderSize+tmSaltLen {
+		return 0
+	}
+	// Validate TLS record header
+	if in[0] != tmContentTypeData {
+		return 0
+	}
+	if in[1] != tmVersionMajor || in[2] != tmVersionMinor {
+		return 0
+	}
+	payloadLen := int(binary.BigEndian.Uint16(in[3:5]))
+	if payloadLen < tmSaltLen || tmHeaderSize+payloadLen > len(in) {
+		return 0
+	}
+	salt := in[tmHeaderSize : tmHeaderSize+tmSaltLen]
+	ciphertext := in[tmHeaderSize+tmSaltLen : tmHeaderSize+payloadLen]
+	o.lk.Lock()
+	key := o.keyLocked(salt)
+	o.lk.Unlock()
+	outLen := len(ciphertext)
+	if len(out) < outLen {
+		return 0
+	}
+	for i, c := range ciphertext {
+		out[i] = c ^ key[i%tmKeyLen]
+	}
+	return outLen
+}
+
+func (o *tlsMimicObfuscator) keyLocked(salt []byte) [tmKeyLen]byte {
+	copy(o.keyInput[len(o.PSK):], salt[:tmSaltLen])
+	return blake2b.Sum256(o.keyInput)
+}
--- a/extras/obfs/tlsmimic_test.go
+++ b/extras/obfs/tlsmimic_test.go
@ -0,0 +1,81 @@
+package obfs
+
+import (
+	"crypto/rand"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTLSMimicObfuscator(t *testing.T) {
+	o, err := newTLSMimicObfuscator([]byte("average_password"))
+	require.NoError(t, err)
+	in := make([]byte, 1200)
+	oOut := make([]byte, 2048)
+	dOut := make([]byte, 2048)
+	for i := 0; i < 1000; i++ {
+		_, _ = rand.Read(in)
+		n := o.Obfuscate(in, oOut)
+		assert.Equal(t, tmHeaderSize+tmSaltLen+len(in), n)
+		// Verify TLS header
+		assert.Equal(t, byte(tmContentTypeData), oOut[0])
+		assert.Equal(t, byte(tmVersionMajor), oOut[1])
+		assert.Equal(t, byte(tmVersionMinor), oOut[2])
+		// Decrypt
+		n = o.Deobfuscate(oOut[:n], dOut)
+		assert.Equal(t, len(in), n)
+		assert.Equal(t, in, dOut[:n])
+	}
+}
+
+func TestTLSMimicPSKTooShort(t *testing.T) {
+	_, err := newTLSMimicObfuscator([]byte("12"))
+	assert.ErrorIs(t, err, errTLSMimicPSKTooShort)
+}
+
+func TestTLSMimicRoundTripSmall(t *testing.T) {
+	o, _ := newTLSMimicObfuscator([]byte("my_psk"))
+	in := []byte("hello")
+	oOut := make([]byte, 2048)
+	dOut := make([]byte, 2048)
+	n := o.Obfuscate(in, oOut)
+	assert.Equal(t, tmHeaderSize+tmSaltLen+len(in), n)
+	n = o.Deobfuscate(oOut[:n], dOut)
+	assert.Equal(t, len(in), n)
+	assert.Equal(t, in, dOut[:n])
+}
+
+func TestTLSMimicRejectInvalidHeader(t *testing.T) {
+	o, _ := newTLSMimicObfuscator([]byte("my_psk"))
+	dOut := make([]byte, 2048)
+	// Wrong content type
+	buf := make([]byte, tmHeaderSize+tmSaltLen+10)
+	n := o.Deobfuscate(buf, dOut)
+	assert.Equal(t, 0, n)
+	// Too short
+	n = o.Deobfuscate(buf[:3], dOut)
+	assert.Equal(t, 0, n)
+}
+
+func BenchmarkTLSMimicObfuscator_Obfuscate(b *testing.B) {
+	o, _ := newTLSMimicObfuscator([]byte("average_password"))
+	in := make([]byte, 1200)
+	_, _ = rand.Read(in)
+	out := make([]byte, 2048)
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		o.Obfuscate(in, out)
+	}
+}
+
+func BenchmarkTLSMimicObfuscator_Deobfuscate(b *testing.B) {
+	o, _ := newTLSMimicObfuscator([]byte("average_password"))
+	in := make([]byte, 1200)
+	_, _ = rand.Read(in)
+	out := make([]byte, 2048)
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		o.Deobfuscate(in, out)
+	}
+}
--- a/extras/outbounds/ob_hysteria.go
+++ b/extras/outbounds/ob_hysteria.go
@ -305,6 +305,8 @@ func wrapObfs(conn net.PacketConn, obfsType, password string, minPacketSize, max
 			MinPacketSize: minPacketSize,
 			MaxPacketSize: maxPacketSize,
 		})
+	case "tlsmimic":
+		return obfs.WrapPacketConnTLSMimic(conn, []byte(password))
 	default:
 		return nil, errors.New("unsupported obfuscation type: " + obfsType)
 	}