feat: add support for multiple server modes (SOCKS5, TPROXY, REDIRECT)

ipkg/CONTROL/control

@@ -1,11 +1,11 @@
 Package: ua3f
 Version: 0.9.0-1
-Depends: luci-compat
+Depends: luci-compat, ipset, iptables, kmod-nft-tproxy, iptables-mod-tproxy, iptables-mod-extra, iptables-mod-nat-extra, kmod-ipt-conntrack
 Source: /feed/openwrt
 SourceName: UA3F
 License: GPL-3.0-only
 Section: net
 SourceDateEpoch: 1711267200
 Architecture: all
-Installed-Size:  3563520
+Installed-Size:  3573760
 Description: Advanced HTTP User-Agent Rewriting Tool.

ipkg/CONTROL/control-e

@@ -1,11 +1,11 @@
 Package: ua3f
 Version: 0.9.0-1
-Depends: luci-compat
+Depends: luci-compat, ipset, iptables, kmod-nft-tproxy, iptables-mod-tproxy, iptables-mod-extra, iptables-mod-nat-extra, kmod-ipt-conntrack
 Source: /feed/openwrt
 SourceName: UA3F
 License: GPL-3.0-only
 Section: net
 SourceDateEpoch: 1711267200
 Architecture: all
-Installed-Size:  3696640
+Installed-Size:  3706880
 Description: Advanced HTTP User-Agent Rewriting Tool.

openwrt/Makefile

@@ -28,7 +28,7 @@ define Package/ua3f
 	SUBMENU:=Web Servers/Proxies
 	TITLE:=A SOCKS5 Server for User-Agent Rewriting
 	URL:=https://github.com/SunBK201/UA3F
-	DEPENDS:=$(GO_ARCH_DEPENDS) +luci-compat
+	DEPENDS:=$(GO_ARCH_DEPENDS) +luci-compat +ipset +iptables +kmod-nft-tproxy +iptables-mod-tproxy +iptables-mod-extra +iptables-mod-nat-extra +kmod-ipt-conntrack
 endef
 
 define Package/ua3f/description

openwrt/files/luci/cbi.lua

@@ -20,10 +20,10 @@ running.cfgvalue = function(self, section)
     local pid = luci.sys.exec("pidof ua3f")
     if pid == "" then
         return "<input disabled type='button' style='opacity: 1;' class='btn cbi-button cbi-button-reset' value='" ..
-        translate("Stop") .. "'/>"
+            translate("Stop") .. "'/>"
     else
         return "<input disabled type='button' style='opacity: 1;' class='btn cbi-button cbi-button-add' value='" ..
-        translate("Running") .. "'/>"
+            translate("Running") .. "'/>"
     end
 end
 
@@ -31,6 +31,11 @@ general:tab("general", translate("Settings"))
 general:tab("stats", translate("Statistics"))
 general:tab("log", translate("Log"))
 
+server_mode = general:taboption("general", ListValue, "server_mode", translate("Server Mode"))
+server_mode:value("SOCKS5", "SOCKS5")
+server_mode:value("TPROXY", "TPROXY")
+server_mode:value("REDIRECT", "REDIRECT")
+
 port = general:taboption("general", Value, "port", translate("Port"))
 port.placeholder = "1080"
 

openwrt/files/ua3f.init

@@ -7,6 +7,198 @@ START=99
 NAME="ua3f"
 PROG="/usr/bin/$NAME"
 
+SERVER_MODE=""
+SERVER_PORT="1080"
+
+FW_BACKEND=""
+NFT_TABLE="UA3F"
+UA3F_CHAIN="UA3F"
+UA3F_OUT_CHAIN="UA3F_OUTPUT"
+IPSET_NAME="localnetwork"
+UA3FMARK="0xc9"
+FWMARK="0x1c9"
+ROUTE_TABLE="0x1c9"
+
+RUNDIR="/var/run/${NAME}"
+[ -d "$RUNDIR" ] || mkdir -p "$RUNDIR"
+ROUTE_CREATED_FLAG="$RUNDIR/route_created"
+IPSET_CREATED_FLAG="$RUNDIR/ipset_created"
+
+log() { logger -t "$NAME" -- "$*"; }
+
+try_modprobe() { command -v modprobe >/dev/null 2>&1 && modprobe "$1" 2>/dev/null; }
+
+nft_available() { command -v nft >/dev/null 2>&1; }
+ipt_available() { command -v iptables >/dev/null 2>&1; }
+detect_backend() {
+    if nft_available; then
+        FW_BACKEND="ipt"
+        return 0
+    fi
+    if ipt_available; then
+        FW_BACKEND="ipt"
+        return 0
+    fi
+    FW_BACKEND=""
+    return 1
+}
+
+ensure_tproxy_route() {
+    ip rule add fwmark "$FWMARK" table "$ROUTE_TABLE" 2>/dev/null
+    ip route add local 0.0.0.0/0 dev lo table "$ROUTE_TABLE" 2>/dev/null
+    echo 1 >"$ROUTE_CREATED_FLAG"
+}
+cleanup_tproxy_route() {
+    ip route del local 0.0.0.0/0 dev lo table "$ROUTE_TABLE" 2>/dev/null
+    ip rule del fwmark "$FWMARK" table "$ROUTE_TABLE" 2>/dev/null
+    rm -f "$ROUTE_CREATED_FLAG"
+}
+
+nft_drop_table() { nft delete table ip "$NFT_TABLE" 2>/dev/null; }
+
+nft_reinit_table() {
+    nft_drop_table
+    nft add table ip "$NFT_TABLE" || return 1
+
+    # set: localnetwork
+    nft "add set ip $NFT_TABLE $IPSET_NAME { type ipv4_addr; flags interval; auto-merge; }" || return 1
+    nft "add element ip $NFT_TABLE $IPSET_NAME { 0.0.0.0/8, 127.0.0.0/8, 10.0.0.0/8, 169.254.0.0/16, 172.16.0.0/12, 192.168.0.0/16, 224.0.0.0/4, 240.0.0.0/4, 100.64.0.0/10 }" >/dev/null 2>&1
+}
+
+fw_setup_nft_tproxy_tcp() {
+    nft_reinit_table || return 1
+    ensure_tproxy_route
+
+    # PREROUTING -> UA3F
+    nft add chain ip $NFT_TABLE prerouting '{ type filter hook prerouting priority mangle; }'
+    nft add rule ip $NFT_TABLE prerouting mark $UA3FMARK return
+    nft add rule ip $NFT_TABLE prerouting ip daddr @$IPSET_NAME return
+    nft add rule ip $NFT_TABLE prerouting ct direction reply return
+    nft add rule ip $NFT_TABLE prerouting meta l4proto tcp mark set $FWMARK tproxy to 127.0.0.1:$SERVER_PORT counter accept
+
+    # OUTPUT -> UA3F_OUTPUT
+    nft add chain ip $NFT_TABLE output '{ type route hook output priority mangle; }'
+    nft add rule ip $NFT_TABLE output mark $UA3FMARK return
+    nft add rule ip $NFT_TABLE output meta skgid 65534 return
+    nft add rule ip $NFT_TABLE output ip daddr @$IPSET_NAME return
+    nft add rule ip $NFT_TABLE output meta l4proto tcp mark set $FWMARK counter accept
+}
+
+fw_setup_nft_redirect_tcp() {
+    nft_reinit_table || return 1
+
+    # PREROUTING -> UA3F
+    nft add chain ip $NFT_TABLE prerouting '{ type nat hook prerouting priority mangle; }'
+    nft add rule ip $NFT_TABLE prerouting mark $UA3FMARK return
+    nft add rule ip $NFT_TABLE prerouting ip daddr @$IPSET_NAME return
+    nft add rule ip $NFT_TABLE prerouting ct direction reply return
+    nft add rule ip $NFT_TABLE prerouting tcp dport != {22} redirect to :$SERVER_PORT
+
+    # OUTPUT -> UA3F_OUTPUT
+    nft add chain ip $NFT_TABLE output '{ type nat hook output priority mangle; }'
+    nft add rule ip $NFT_TABLE output mark $UA3FMARK return
+    nft add rule ip $NFT_TABLE output meta skgid 65534 return
+    nft add rule ip $NFT_TABLE output ip daddr @$IPSET_NAME return
+    nft add rule ip $NFT_TABLE output tcp dport != {22} redirect to :$SERVER_PORT
+}
+
+fw_revert_nft() {
+    nft_drop_table
+    [ -f "$ROUTE_CREATED_FLAG" ] && cleanup_tproxy_route
+}
+
+ensure_local_set_ipt() {
+    if ! ipset list "$IPSET_NAME" >/dev/null 2>&1; then
+        ipset create "$IPSET_NAME" hash:net maxelem 1048576 || return 1
+        echo 1 >"$IPSET_CREATED_FLAG"
+        ipset add "$IPSET_NAME" 0.0.0.0/8
+        ipset add "$IPSET_NAME" 127.0.0.0/8
+        ipset add "$IPSET_NAME" 10.0.0.0/8
+        ipset add "$IPSET_NAME" 169.254.0.0/16
+        ipset add "$IPSET_NAME" 172.16.0.0/12
+        ipset add "$IPSET_NAME" 192.168.0.0/16
+        ipset add "$IPSET_NAME" 224.0.0.0/4
+        ipset add "$IPSET_NAME" 240.0.0.0/4
+        ipset add "$IPSET_NAME" 100.64.0.0/10
+    fi
+}
+
+fw_setup_ipt_tproxy_tcp() {
+    ensure_local_set_ipt || return 1
+    ensure_tproxy_route
+
+    # PREROUTING
+    iptables -t mangle -F "$UA3F_CHAIN" 2>/dev/null
+    iptables -t mangle -D PREROUTING -p tcp -j "$UA3F_CHAIN" 2>/dev/null
+    iptables -t mangle -X "$UA3F_CHAIN" 2>/dev/null
+    iptables -t mangle -N "$UA3F_CHAIN"
+    iptables -t mangle -A PREROUTING -p tcp -j "$UA3F_CHAIN"
+    iptables -t mangle -A "$UA3F_CHAIN" -p tcp -m mark --mark "$UA3FMARK" -j RETURN
+    iptables -t mangle -A "$UA3F_CHAIN" -m set --match-set "$IPSET_NAME" dst -j RETURN
+    iptables -t mangle -A "$UA3F_CHAIN" -m conntrack --ctdir REPLY -j RETURN
+    iptables -t mangle -A "$UA3F_CHAIN" -p tcp -j TPROXY --on-port "$SERVER_PORT" --tproxy-mark "$FWMARK"
+
+    # OUTPUT
+    iptables -t mangle -F "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t mangle -D OUTPUT -p tcp -j "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t mangle -X "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t mangle -N "$UA3F_OUT_CHAIN"
+    iptables -t mangle -A OUTPUT -p tcp -j "$UA3F_OUT_CHAIN"
+    iptables -t mangle -A "$UA3F_OUT_CHAIN" -p tcp -m mark --mark "$UA3FMARK" -j RETURN
+    iptables -t mangle -A "$UA3F_OUT_CHAIN" -p tcp -m owner --gid-owner 65534 -j RETURN
+    iptables -t mangle -A "$UA3F_OUT_CHAIN" -m set --match-set "$IPSET_NAME" dst -j RETURN
+    iptables -t mangle -A "$UA3F_OUT_CHAIN" -p tcp -j MARK --set-mark "$FWMARK"
+}
+
+fw_setup_ipt_redirect_tcp() {
+    ensure_local_set_ipt || return 1
+
+    # PREROUTING
+    iptables -t nat -F "$UA3F_CHAIN" 2>/dev/null
+    iptables -t nat -D PREROUTING -p tcp -j "$UA3F_CHAIN" 2>/dev/null
+    iptables -t nat -X "$UA3F_CHAIN" 2>/dev/null
+    iptables -t nat -N "$UA3F_CHAIN"
+    iptables -t nat -A PREROUTING -p tcp -j "$UA3F_CHAIN"
+    iptables -t nat -A "$UA3F_CHAIN" -p tcp -m mark --mark "$UA3FMARK" -j RETURN
+    iptables -t nat -A "$UA3F_CHAIN" -m set --match-set "$IPSET_NAME" dst -j RETURN
+    iptables -t nat -A "$UA3F_CHAIN" -m conntrack --ctdir REPLY -j RETURN
+    iptables -t nat -A "$UA3F_CHAIN" -p tcp -j REDIRECT --to-ports "$SERVER_PORT"
+
+    # OUTPUT
+    iptables -t nat -F "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t nat -D OUTPUT -p tcp -j "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t nat -X "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t nat -N "$UA3F_OUT_CHAIN"
+    iptables -t nat -A OUTPUT -p tcp -j "$UA3F_OUT_CHAIN"
+    iptables -t nat -A "$UA3F_OUT_CHAIN" -p tcp -m mark --mark "$UA3FMARK" -j RETURN
+    iptables -t nat -A "$UA3F_OUT_CHAIN" -p tcp -m owner --gid-owner 65534 -j RETURN
+    iptables -t nat -A "$UA3F_OUT_CHAIN" -m set --match-set "$IPSET_NAME" dst -j RETURN
+    iptables -t nat -A "$UA3F_OUT_CHAIN" -p tcp -j REDIRECT --to-ports "$SERVER_PORT"
+}
+
+fw_revert_ipt() {
+    # mangle
+    iptables -t mangle -D PREROUTING -p tcp -j "$UA3F_CHAIN" 2>/dev/null
+    iptables -t mangle -F "$UA3F_CHAIN" 2>/dev/null
+    iptables -t mangle -X "$UA3F_CHAIN" 2>/dev/null
+    iptables -t mangle -D OUTPUT -p tcp -j "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t mangle -F "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t mangle -X "$UA3F_OUT_CHAIN" 2>/dev/null
+    # nat
+    iptables -t nat -D PREROUTING -p tcp -j "$UA3F_CHAIN" 2>/dev/null
+    iptables -t nat -F "$UA3F_CHAIN" 2>/dev/null
+    iptables -t nat -X "$UA3F_CHAIN" 2>/dev/null
+    iptables -t nat -D OUTPUT -p tcp -j "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t nat -F "$UA3F_OUT_CHAIN" 2>/dev/null
+    iptables -t nat -X "$UA3F_OUT_CHAIN" 2>/dev/null
+    # ipset
+    if [ -f "$IPSET_CREATED_FLAG" ]; then
+        ipset destroy "$IPSET_NAME" 2>/dev/null
+        rm -f "$IPSET_CREATED_FLAG"
+    fi
+    [ -f "$ROUTE_CREATED_FLAG" ] && cleanup_tproxy_route
+}
+
 start_service() {
     config_load "$NAME"
 
@@ -16,12 +208,8 @@ start_service() {
         return 1
     fi
 
-    local port
+    local server_mode port bind ua log_level ua_regex partial_replace
-    local bind
+    config_get server_mode "main" "server_mode" "SOCKS5"
-    local ua
-    local log_level
-    local ua_regex
-    local partial_replace
     config_get port "main" "port" "1080"
     config_get bind "main" "bind" "127.0.0.1"
     config_get ua "main" "ua" "FFF"
@@ -29,13 +217,67 @@ start_service() {
     config_get_bool partial_replace "main" "partial_replace" 0
     config_get log_level "main" "log_level" "info"
 
+    SERVER_MODE="$(echo "$server_mode" | tr '[:lower:]' '[:upper:]')"
+    SERVER_MODE="$server_mode"
+
     mkdir -p /var/log/ua3f
     chmod o+w /var/log/ua3f
 
+    detect_backend || {
+        log "no firewall backend found"
+        return 1
+    }
+
+    # Always cleanup first (idempotent)
+    if [ "$FW_BACKEND" = "nft" ]; then
+        fw_revert_nft
+    else
+        fw_revert_ipt
+    fi
+
+    case "$SERVER_MODE" in
+    SOCKS5)
+        # No firewall interception
+        ;;
+    TPROXY)
+        if [ "$FW_BACKEND" = "nft" ]; then
+            try_modprobe nft_tproxy
+            fw_setup_nft_tproxy_tcp || {
+                log "nft TPROXY setup failed"
+                return 1
+            }
+        else
+            try_modprobe xt_TPROXY
+            fw_setup_ipt_tproxy_tcp || {
+                log "iptables TPROXY setup failed"
+                return 1
+            }
+        fi
+        ;;
+    REDIRECT)
+        if [ "$FW_BACKEND" = "nft" ]; then
+            fw_setup_nft_redirect_tcp || {
+                log "nft REDIRECT setup failed"
+                return 1
+            }
+        else
+            fw_setup_ipt_redirect_tcp || {
+                log "iptables REDIRECT setup failed"
+                return 1
+            }
+        fi
+        ;;
+    *)
+        log "unknown server_mode: $SERVER_MODE"
+        return 1
+        ;;
+    esac
+
     procd_open_instance "$NAME"
     procd_set_param command "$PROG"
-    procd_append_param command -b "$bind"
+    procd_append_param command -m "$server_mode"
     procd_append_param command -p $port
+    procd_append_param command -b "$bind"
     procd_append_param command -f "$ua"
     procd_append_param command -r "$ua_regex"
     procd_append_param command -l $log_level
@@ -56,6 +298,15 @@ start_service() {
     procd_close_instance
 }
 
+stop_service() {
+    detect_backend
+    if [ "$FW_BACKEND" = "nft" ]; then
+        fw_revert_nft
+    else
+        fw_revert_ipt
+    fi
+}
+
 reload_service() {
     stop
     start

openwrt/files/ua3f.uci

@@ -2,6 +2,7 @@ config 'ua3f' 'enabled'
 	option enabled '0'
 
 config 'ua3f' 'main'
+    option server_mode 'SOCKS5'
     option port '1080'
     option bind '127.0.0.1'
 	option ua 'FFF'

openwrt/po/zh_cn/ua3f.po

@@ -26,6 +26,9 @@ msgstr "统计信息"
 msgid "Log"
 msgstr "运行日志"
 
+msgid "Server Mode"
+msgstr "服务模式"
+
 msgid "Port"
 msgstr "端口"
 

src/go.mod

@@ -6,10 +6,8 @@ require (
 	github.com/dlclark/regexp2 v1.11.4
 	github.com/hashicorp/golang-lru/v2 v2.0.7
 	github.com/sirupsen/logrus v1.9.3
+	golang.org/x/sys v0.26.0
 	gopkg.in/natefinch/lumberjack.v2 v2.2.1
 )
 
-require (
+require github.com/stretchr/testify v1.8.2 // indirect
-	github.com/stretchr/testify v1.8.2 // indirect
-	golang.org/x/sys v0.26.0 // indirect
-)

src/internal/config/config.go

@@ -3,11 +3,13 @@ package config
 import (
 	"flag"
 	"fmt"
+	"strings"
 )
 
 const (
-	ServerModeSocks5 = "socks5"
+	ServerModeSocks5   = "SOCKS5"
-	ServerModeTProxy = "tproxy"
+	ServerModeTProxy   = "TPROXY"
+	ServerModeRedirect = "REDIRECT"
 )
 
 type Config struct {
@@ -33,7 +35,7 @@ func Parse() (*Config, bool) {
 		showVer    bool
 	)
 
-	flag.StringVar(&serverMode, "m", ServerModeSocks5, "server mode: socks5 or tproxy (default: socks5)")
+	flag.StringVar(&serverMode, "m", ServerModeSocks5, "server mode: SOCKS5, TPROXY, REDIRECT (default: SOCKS5)")
 	flag.StringVar(&bindAddr, "b", "127.0.0.1", "bind address (default: 127.0.0.1)")
 	flag.IntVar(&port, "p", 1080, "port")
 	flag.StringVar(&payloadUA, "f", "FFF", "User-Agent")
@@ -44,7 +46,7 @@ func Parse() (*Config, bool) {
 	flag.Parse()
 
 	cfg := &Config{
-		ServerMode:           serverMode,
+		ServerMode:           strings.ToUpper(serverMode),
 		BindAddr:             bindAddr,
 		Port:                 port,
 		ListenAddr:           fmt.Sprintf("%s:%d", bindAddr, port),

src/internal/log/log.go

@@ -65,6 +65,7 @@ func SetLogConf(level string) {
 
 func LogHeader(version string, cfg *config.Config) {
 	logrus.Info("UA3F v" + version)
+	logrus.Info("Server Mode: " + cfg.ServerMode)
 	logrus.Infof("Listen on %s", cfg.ListenAddr)
 	logrus.Infof("User-Agent: %s", cfg.PayloadUA)
 	logrus.Infof("User-Agent Regex Pattern: '%s'", cfg.UAPattern)

src/internal/server/redirect/redirect_linux.go

@@ -0,0 +1,92 @@
+//go:build linux
+
+package redirect
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/sirupsen/logrus"
+	"github.com/sunbk201/ua3f/internal/config"
+	"github.com/sunbk201/ua3f/internal/rewrite"
+	"github.com/sunbk201/ua3f/internal/server/utils"
+	"github.com/sunbk201/ua3f/internal/statistics"
+	"golang.org/x/sys/unix"
+)
+
+type Server struct {
+	cfg      *config.Config
+	rw       *rewrite.Rewriter
+	listener net.Listener
+}
+
+func New(cfg *config.Config, rw *rewrite.Rewriter) *Server {
+	return &Server{
+		cfg: cfg,
+		rw:  rw,
+	}
+}
+
+func (s *Server) Start() (err error) {
+	if s.listener, err = net.Listen("tcp", s.cfg.ListenAddr); err != nil {
+		return fmt.Errorf("listen failed: %w", err)
+	}
+
+	go statistics.StartRecorder()
+
+	var client net.Conn
+	for {
+		if client, err = s.listener.Accept(); err != nil {
+			logrus.Error("Accept failed: ", err)
+			continue
+		}
+		logrus.Debugf("Accept connection from %s", client.RemoteAddr().String())
+		go s.HandleClient(client)
+	}
+}
+
+func (s *Server) HandleClient(client net.Conn) {
+	addr, err := getOriginalDstAddr(client)
+	if err != nil {
+		_ = client.Close()
+		logrus.Errorf("Get original dst addr failed: %v", err)
+		return
+	}
+	logrus.Debugf("Original destination address: %s", addr)
+
+	target, err := utils.ConnectWithMark(addr, utils.SO_MARK)
+	if err != nil {
+		_ = client.Close()
+		logrus.Errorf("Dial target %s failed: %v", addr, err)
+		return
+	}
+
+	s.ForwardTCP(client, target, addr)
+}
+
+// ForwardTCP proxies traffic in both directions.
+// target->client uses raw copy.
+// client->target is processed by the rewriter (or raw if cached).
+func (s *Server) ForwardTCP(client, target net.Conn, destAddr string) {
+	// Server -> Client (raw)
+	go utils.CopyHalf(client, target)
+
+	// Client -> Server (rewriter)
+	go utils.ProxyHalf(target, client, s.rw, destAddr)
+}
+
+// getOriginalDstAddr retrieves the original destination address of the redirected connection.
+func getOriginalDstAddr(conn net.Conn) (addr string, err error) {
+	fd, err := utils.GetConnFD(conn)
+	if err != nil {
+		return "", fmt.Errorf("failed to get file descriptor: %v", err)
+	}
+	raw, err := unix.GetsockoptIPv6Mreq(fd, unix.SOL_IP, unix.SO_ORIGINAL_DST)
+	if err != nil {
+		return "", fmt.Errorf("getsockopt SO_ORIGINAL_DST failed: %v", err)
+	}
+
+	ip := net.IPv4(raw.Multiaddr[4], raw.Multiaddr[5], raw.Multiaddr[6], raw.Multiaddr[7])
+	port := uint16(raw.Multiaddr[2])<<8 + uint16(raw.Multiaddr[3])
+	return fmt.Sprintf("%s:%d", ip.String(), port), nil
+}

src/internal/server/redirect/redirect_others.go

@@ -0,0 +1,37 @@
+//go:build !linux
+
+package redirect
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/sunbk201/ua3f/internal/config"
+	"github.com/sunbk201/ua3f/internal/rewrite"
+	"github.com/sunbk201/ua3f/internal/server/utils"
+)
+
+type Server struct {
+	cfg *config.Config
+	rw  *rewrite.Rewriter
+}
+
+func New(cfg *config.Config, rw *rewrite.Rewriter) *Server {
+	return &Server{
+		cfg: cfg,
+		rw:  rw,
+	}
+}
+
+func (s *Server) Start() error {
+	return fmt.Errorf("REDIRECT Mode is only supported on Linux")
+}
+
+func (s *Server) HandleClient(client net.Conn) {
+	defer client.Close()
+}
+
+func (s *Server) ForwardTCP(client, target net.Conn, _ string) {
+	go utils.CopyHalf(client, target)
+	go utils.CopyHalf(target, client)
+}

src/internal/server/server.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/sunbk201/ua3f/internal/config"
 	"github.com/sunbk201/ua3f/internal/rewrite"
+	"github.com/sunbk201/ua3f/internal/server/redirect"
 	"github.com/sunbk201/ua3f/internal/server/socks5"
 	"github.com/sunbk201/ua3f/internal/server/tproxy"
 )
@@ -20,6 +21,10 @@ func NewServer(cfg *config.Config, rw *rewrite.Rewriter) (Server, error) {
 	switch cfg.ServerMode {
 	case config.ServerModeSocks5:
 		return socks5.New(cfg, rw), nil
+	case config.ServerModeTProxy:
+		return tproxy.New(cfg, rw), nil
+	case config.ServerModeRedirect:
+		return redirect.New(cfg, rw), nil
 	default:
 		return nil, fmt.Errorf("unknown server mode: %s", cfg.ServerMode)
 	}

src/internal/server/tproxy/tproxy_linux.go

@@ -0,0 +1,113 @@
+//go:build linux
+
+package tproxy
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/sirupsen/logrus"
+	"github.com/sunbk201/ua3f/internal/config"
+	"github.com/sunbk201/ua3f/internal/rewrite"
+	"github.com/sunbk201/ua3f/internal/server/utils"
+	"github.com/sunbk201/ua3f/internal/statistics"
+)
+
+type Server struct {
+	cfg      *config.Config
+	rw       *rewrite.Rewriter
+	listener net.Listener
+}
+
+func New(cfg *config.Config, rw *rewrite.Rewriter) *Server {
+	return &Server{
+		cfg: cfg,
+		rw:  rw,
+	}
+}
+
+func (s *Server) Start() error {
+	lc := net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			var err error
+			c.Control(func(fd uintptr) {
+				if e := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEADDR, 1); e != nil {
+					err = fmt.Errorf("set SO_REUSEADDR: %v", e)
+					return
+				}
+				if e := unix.SetsockoptInt(int(fd), unix.SOL_IP, unix.IP_TRANSPARENT, 1); e != nil {
+					err = fmt.Errorf("set IP_TRANSPARENT: %v", e)
+					return
+				}
+			})
+			return err
+		},
+	}
+
+	var err error
+	if s.listener, err = lc.Listen(context.TODO(), "tcp", s.cfg.ListenAddr); err != nil {
+		return fmt.Errorf("listen failed: %w", err)
+	}
+
+	go statistics.StartRecorder()
+
+	var client net.Conn
+	for {
+		if client, err = s.listener.Accept(); err != nil {
+			logrus.Error("Accept failed: ", err)
+			continue
+		}
+		logrus.Debugf("Accept connection from %s", client.RemoteAddr().String())
+		go s.HandleClient(client)
+	}
+}
+
+func (s *Server) HandleClient(client net.Conn) {
+	addr, err := getOriginalDstAddr(client)
+	if err != nil {
+		_ = client.Close()
+		logrus.Errorf("Get original dst addr failed: %v", err)
+		return
+	}
+	logrus.Debugf("Original destination address: %s", addr)
+
+	target, err := utils.ConnectWithMark(addr, utils.SO_MARK)
+	if err != nil {
+		_ = client.Close()
+		logrus.Errorf("Dial target %s failed: %v", addr, err)
+		return
+	}
+
+	s.ForwardTCP(client, target, addr)
+}
+
+// ForwardTCP proxies traffic in both directions.
+// target->client uses raw copy.
+// client->target is processed by the rewriter (or raw if cached).
+func (s *Server) ForwardTCP(client, target net.Conn, destAddr string) {
+	// Server -> Client (raw)
+	go utils.CopyHalf(client, target)
+
+	// Client -> Server (rewriter)
+	go utils.ProxyHalf(target, client, s.rw, destAddr)
+}
+
+// getOriginalDstAddr retrieves the original destination address of a TProxy connection.
+func getOriginalDstAddr(conn net.Conn) (addr string, err error) {
+	fd, err := utils.GetConnFD(conn)
+	if err != nil {
+		return "", fmt.Errorf("failed to get file descriptor: %v", err)
+	}
+	raw, err := unix.GetsockoptIPv6Mreq(fd, unix.SOL_IP, unix.SO_ORIGINAL_DST)
+	if err != nil {
+		return "", fmt.Errorf("getsockopt SO_ORIGINAL_DST failed: %v", err)
+	}
+
+	ip := net.IPv4(raw.Multiaddr[4], raw.Multiaddr[5], raw.Multiaddr[6], raw.Multiaddr[7])
+	port := uint16(raw.Multiaddr[2])<<8 + uint16(raw.Multiaddr[3])
+	return fmt.Sprintf("%s:%d", ip.String(), port), nil
+}

src/internal/server/tproxy/tproxy_others.go

@@ -0,0 +1,37 @@
+//go:build !linux
+
+package tproxy
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/sunbk201/ua3f/internal/config"
+	"github.com/sunbk201/ua3f/internal/rewrite"
+	"github.com/sunbk201/ua3f/internal/server/utils"
+)
+
+type Server struct {
+	cfg *config.Config
+	rw  *rewrite.Rewriter
+}
+
+func New(cfg *config.Config, rw *rewrite.Rewriter) *Server {
+	return &Server{
+		cfg: cfg,
+		rw:  rw,
+	}
+}
+
+func (s *Server) Start() error {
+	return fmt.Errorf("TPROXY Mode is only supported on Linux")
+}
+
+func (s *Server) HandleClient(client net.Conn) {
+	defer client.Close()
+}
+
+func (s *Server) ForwardTCP(client, target net.Conn, _ string) {
+	go utils.CopyHalf(client, target)
+	go utils.CopyHalf(target, client)
+}

src/internal/server/utils/tcp.go

@@ -1,6 +1,7 @@
 package utils
 
 import (
+	"fmt"
 	"io"
 	"net"
 
@@ -9,12 +10,12 @@ import (
 )
 
 // Connect dials the target address and returns the connection.
-func Connect(Addr string) (target net.Conn, err error) {
+func Connect(addr string) (target net.Conn, err error) {
-	logrus.Debugf("Connecting %s", Addr)
+	logrus.Debugf("Connecting %s", addr)
-	if target, err = net.Dial("tcp", Addr); err != nil {
+	if target, err = net.Dial("tcp", addr); err != nil {
 		return nil, err
 	}
-	logrus.Debugf("Connected %s", Addr)
+	logrus.Debugf("Connected %s", addr)
 	return target, nil
 }
 
@@ -52,3 +53,16 @@ func ProxyHalf(dst, src net.Conn, rw *rewrite.Rewriter, destAddrPort string) {
 	}()
 	_ = rw.ProxyHTTPOrRaw(dst, src, destAddrPort)
 }
+
+func GetConnFD(conn net.Conn) (fd int, err error) {
+	tcpConn, ok := conn.(*net.TCPConn)
+	if !ok {
+		return 0, fmt.Errorf("not a TCP connection")
+	}
+	file, err := tcpConn.File()
+	if err != nil {
+		return 0, err
+	}
+
+	return int(file.Fd()), nil
+}

src/internal/server/utils/tcp_linux.go

@@ -0,0 +1,34 @@
+//go:build linux
+
+package utils
+
+import (
+	"net"
+	"syscall"
+
+	"github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+const SO_MARK = 0xc9
+
+// ConnectWithMark dials the target address with SO_MARK set and returns the connection.
+func ConnectWithMark(addr string, mark int) (target net.Conn, err error) {
+	logrus.Debugf("Connecting %s with SO_MARK=%d", addr, mark)
+
+	dialer := net.Dialer{
+		Control: func(network, address string, c syscall.RawConn) error {
+			return c.Control(func(fd uintptr) {
+				unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, mark)
+			})
+		},
+	}
+
+	conn, err := dialer.Dial("tcp", addr)
+	if err != nil {
+		return nil, err
+	}
+
+	logrus.Debugf("Connected %s with SO_MARK=%d", addr, mark)
+	return conn, nil
+}