fix: fix ufw

The panel's ufw integration needs root; the database now lives next to
the binary in /opt/lpra.

README.md

@@ -42,6 +42,23 @@ curl -fsSL https://localhost:8445/install.sh | sudo HOST=https://localhost:8445
 curl -fsSL https://localhost:8445/install.sh | sudo sh
 ```
 
+## Проброс портов и прямой туннель
+Правила проброса создаются на странице машины. Режим `http` идёт через адрес панели (long-poll),
+режимы `tcp`/`udp` — через прямой туннель: агент держит исходящее соединение к порту туннеля хоста
+(по умолчанию `8446`, флаг `-tunnel` / `LPRA_TUNNEL_ADDR`).
+
+Порт туннеля и хост, к которому для него подключаются агенты (например, IP вместо домена панели),
+меняются в `/settings` → «Прямой туннель». Агенты забирают адрес с панели сами — при подключении и
+при каждом опросе, переустановка не нужна. Локальные `TUNNEL_ADDR` / `TUNNEL_PORT` в окружении агента
+имеют приоритет над настройкой панели (`TUNNEL_ADDR=off` отключает туннель).
+
+Если на хосте активен ufw и сервер запущен от root, панель сама открывает порт хоста правила
+(tcp для `http`/`tcp`, udp для `udp`) и порт туннеля для прямых режимов, а при удалении правила — закрывает.
+При `ProtectSystem=strict` в systemd-юните ufw нужны права на запись: `ReadWritePaths=/etc/ufw /run`.
+
+## Версия
+Версия задаётся в одном месте — `VERSION.txt`; файл вшивается в сервер и агент при сборке.
+
 ## Пользователь терминала
 По умолчанию терминал открывается от пользователя, под которым запущен агент (на Linux — root).
 В окне «Изменить машину» можно выбрать другого пользователя машины или создать нового

VERSION.txt

@@ -1 +1 @@
-0.0.2
+0.0.3

build.sh

@@ -5,10 +5,9 @@ set -eu
 
 cd "$(dirname "$0")"
 
-VERSION="${VERSION:-$(cat VERSION.txt 2>/dev/null || echo 0.0.0)}"
+# The version comes from VERSION.txt, which is embedded into every binary.
-PKG="github.com/x-grk/longpolling-remote-access"
+LDFLAGS="-s -w"
-LDFLAGS="-s -w -X $PKG/internal/server.Version=$VERSION -X $PKG/internal/agent.Version=$VERSION"
+echo ">> version $(cat VERSION.txt)"
-echo ">> version $VERSION"
 
 mkdir -p dist bin
 

cmd/agent/main.go

@@ -23,6 +23,8 @@ func main() {
 		Name:         os.Getenv("AGENT_NAME"),
 		StatePath:    envOr("STATE_PATH", "/etc/lpagent/state.json"),
 		TunnelAddr:   tunnelAddr(host),
+		// A locally set address wins over the one from the panel settings.
+		TunnelPinned: os.Getenv("TUNNEL_ADDR") != "" || os.Getenv("TUNNEL_PORT") != "",
 	}
 	if cfg.EnrollSecret == "" {
 		// Only required for the very first run (before enrollment).
@@ -47,8 +49,9 @@ func envOr(key, def string) string {
 }
 
 // tunnelAddr derives the direct-tunnel address (host:8446) from the server URL.
-// TUNNEL_ADDR overrides it entirely; TUNNEL_PORT overrides just the port.
+// It is only the starting point: the agent follows the host and port set in
-// Set TUNNEL_ADDR=off to disable the direct tunnel.
+// the panel settings, unless TUNNEL_ADDR (the whole address) or TUNNEL_PORT
+// (just the port) pins it here. Set TUNNEL_ADDR=off to disable the tunnel.
 func tunnelAddr(hostURL string) string {
 	if v := os.Getenv("TUNNEL_ADDR"); v != "" {
 		if v == "off" {

deploy/lpra-server.service

@@ -1,24 +1,24 @@
 # systemd unit for the LPRA host (server).
 #
-# Unlike the agent, the server does NOT need root: it listens on a high local
+# The server runs as root so that the panel can open forwarded ports in ufw;
-# port (127.0.0.1:8091) behind nginx, so run it as an unprivileged user.
+# it listens on a high local port (127.0.0.1:8091) behind nginx.
 #
 # Install:
-#   sudo useradd --system --home /opt/lpra --shell /usr/sbin/nologin lpra
+#   sudo mkdir -p /opt/lpra
-#   sudo mkdir -p /opt/lpra /var/lib/lpra
 #   sudo cp bin/lpra-server /opt/lpra/
 #   sudo cp -r dist /opt/lpra/dist           # agent binaries served at /download/
-#   sudo chown -R lpra:lpra /opt/lpra /var/lib/lpra
 #   sudo cp deploy/lpra-server.service /etc/systemd/system/
 #   sudo systemctl daemon-reload && sudo systemctl enable --now lpra-server
 #
-# Config overrides can go in /etc/lpra-server.env (see EnvironmentFile below),
-# e.g.  LPRA_ADDR=127.0.0.1:8091
-#
 # Direct port forwarding (tcp/udp modes) uses port 8446 on the host — open it in
 # the firewall:  ufw allow 8446/tcp ; ufw allow 8446/udp
 # (The "http" forward mode and terminal/files go through nginx :8445 and need
 # nothing extra.) Override with LPRA_TUNNEL_ADDR, or set it empty to disable.
+# The port, and the host agents dial for it, can also be changed in the panel
+# settings; agents pick the new address up from the panel by themselves.
+#
+# ufw integration (the panel opening forwarded ports itself) needs root and a
+# writable /etc/ufw and /run — see ReadWritePaths below.
 
 [Unit]
 Description=LPRA remote access host (admin panel + agent rendezvous)
@@ -26,17 +26,11 @@ After=network-online.target
 Wants=network-online.target
 
 [Service]
-Type=simple
-User=lpra
-Group=lpra
 WorkingDirectory=/opt/lpra
 
-# Optional environment overrides; "-" means the file is not required.
-EnvironmentFile=-/etc/lpra-server.env
-
 ExecStart=/opt/lpra/lpra-server \
     -addr 127.0.0.1:8091 \
-    -db /var/lib/lpra/lpra.db \
+    -db /opt/lpra/lpra.db \
     -dist /opt/lpra/dist
 
 Restart=always
@@ -51,8 +45,11 @@ PrivateDevices=true
 ProtectKernelTunables=true
 ProtectControlGroups=true
 RestrictSUIDSGID=true
-# The server only needs to write its SQLite database here.
+# The SQLite database, plus what ufw writes: its rules in /etc/ufw and the
-ReadWritePaths=/var/lib/lpra
+# ufw/xtables locks in /run. Without the last two "ufw status" works but
+# "ufw allow" fails with "'/etc/ufw/user.rules' is not writable".
+ReadWritePaths=/opt/lpra /etc/ufw /run
+ReadWritePaths-=/etc/ufw /run
 
 [Install]
 WantedBy=multi-user.target

internal/agent/client.go

@@ -13,17 +13,19 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"net/url"
 	"os"
 	"path/filepath"
 	"runtime"
+	"sync"
 	"time"
 
+	lpra "github.com/x-grk/longpolling-remote-access"
 	"github.com/x-grk/longpolling-remote-access/internal/proto"
 )
 
-// Version is the agent build version, injected at compile time via -ldflags
+// Version is the agent build version (see VERSION.txt).
-// (-X .../internal/agent.Version=...).
+var Version = lpra.Version
-var Version = "dev"
 
 // Config is the agent's runtime configuration (from env / config.env).
 type Config struct {
@@ -32,6 +34,9 @@ type Config struct {
 	Name         string // optional friendly name
 	StatePath    string // where the enrolled id+token are persisted
 	TunnelAddr   string // host:port for the direct forward tunnel (e.g. REDACTED:8446); empty disables
+	// TunnelPinned keeps TunnelAddr as configured locally (TUNNEL_ADDR /
+	// TUNNEL_PORT) instead of following the address set in the panel.
+	TunnelPinned bool
 }
 
 type state struct {
@@ -45,6 +50,11 @@ type Agent struct {
 	http      *http.Client
 	state     state
 	pollCount int
+
+	// Direct tunnel currently running (see setTunnelAddr).
+	tunMu     sync.Mutex
+	tunAddr   string
+	tunCancel context.CancelFunc
 }
 
 // New builds an agent. It does not perform any network I/O.
@@ -87,10 +97,11 @@ func (a *Agent) Run(ctx context.Context) error {
 	}
 	log.Printf("agent %s connected to %s", a.state.AgentID, a.cfg.Host)
 
-	// Direct forward tunnel (low-latency TCP mux + UDP) on 8446, if configured.
+	// Direct forward tunnel (low-latency TCP mux + UDP). Its address comes
-	if a.cfg.TunnelAddr != "" {
+	// from the panel; fall back to the configured one when the server sends
-		go a.runTunnel(ctx)
+	// none (tunnel port left at the default on an older server).
-		go a.runUDP(ctx)
+	if a.cfg.TunnelPinned || !a.fetchConfig(ctx) {
+		a.setTunnelAddr(ctx, a.cfg.TunnelAddr)
 	}
 
 	backoff := time.Second
@@ -168,6 +179,7 @@ func (a *Agent) pollOnce(ctx context.Context) error {
 	if err := json.NewDecoder(resp.Body).Decode(&msg); err != nil {
 		return err
 	}
+	a.applyTunnelHeader(ctx, resp.Header)
 	// Dispatch in the background so we keep polling for more work.
 	switch msg.Type {
 	case proto.CtrlOpenTerminal:
@@ -180,6 +192,66 @@ func (a *Agent) pollOnce(ctx context.Context) error {
 	return nil
 }
 
+// fetchConfig asks the server for the settings it hands to agents and reports
+// whether it named a tunnel address.
+func (a *Agent) fetchConfig(ctx context.Context) bool {
+	ctx2, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+	req, _ := http.NewRequestWithContext(ctx2, http.MethodGet, a.cfg.Host+"/api/agent/config", nil)
+	a.authHeaders(req)
+	resp, err := a.http.Do(req)
+	if err != nil {
+		return false
+	}
+	defer resp.Body.Close()
+	return a.applyTunnelHeader(ctx, resp.Header)
+}
+
+// applyTunnelHeader follows the tunnel address the server advertises as
+// "host:port"; an empty host means the host we already reach the server on.
+func (a *Agent) applyTunnelHeader(ctx context.Context, h http.Header) bool {
+	v := h.Get("X-Tunnel-Addr")
+	if v == "" || a.cfg.TunnelPinned {
+		return false
+	}
+	host, port, err := net.SplitHostPort(v)
+	if err != nil {
+		return false
+	}
+	if host == "" {
+		u, err := url.Parse(a.cfg.Host)
+		if err != nil || u.Hostname() == "" {
+			return false
+		}
+		host = u.Hostname()
+	}
+	a.setTunnelAddr(ctx, net.JoinHostPort(host, port))
+	return true
+}
+
+// setTunnelAddr points the direct tunnel at addr, restarting it if it was
+// running against another address. An empty addr stops it.
+func (a *Agent) setTunnelAddr(ctx context.Context, addr string) {
+	a.tunMu.Lock()
+	defer a.tunMu.Unlock()
+	if addr == a.tunAddr {
+		return
+	}
+	if a.tunCancel != nil {
+		a.tunCancel()
+		a.tunCancel = nil
+	}
+	a.tunAddr = addr
+	if addr == "" {
+		return
+	}
+	log.Printf("tunnel: using %s", addr)
+	tctx, cancel := context.WithCancel(ctx)
+	a.tunCancel = cancel
+	go a.runTunnel(tctx, addr)
+	go a.runUDP(tctx, addr)
+}
+
 func (a *Agent) authHeaders(req *http.Request) {
 	req.Header.Set("X-Agent-Id", a.state.AgentID)
 	req.Header.Set("Authorization", "Bearer "+a.state.Token)

internal/agent/fs.go

@@ -17,8 +17,8 @@ import (
 	"github.com/x-grk/longpolling-remote-access/internal/proto"
 )
 
-// fsReadCap bounds how many bytes a view/read returns (5 MiB).
+// fsReadCap bounds how many bytes a view/read returns.
-const fsReadCap = 5 * 1024 * 1024
+const fsReadCap = proto.FSReadCap
 
 // fsDownloadCap bounds a browser download (kept under the 64 MiB result/body
 // limit once base64-encoded).

internal/agent/tunnel.go

@@ -15,12 +15,12 @@ import (
 
 // --- direct TCP mux tunnel ---
 
-// runTunnel keeps a persistent connection to the host's 8446 tunnel, dialing
+// runTunnel keeps a persistent connection to the host's tunnel at addr, dialing
-// client-side ports on demand for "tcp" forward rules.
+// client-side ports on demand for "tcp" forward rules, until ctx is cancelled.
-func (a *Agent) runTunnel(ctx context.Context) {
+func (a *Agent) runTunnel(ctx context.Context, addr string) {
 	backoff := time.Second
 	for ctx.Err() == nil {
-		if err := a.tunnelOnce(ctx); err != nil {
+		if err := a.tunnelOnce(ctx, addr); err != nil {
 			select {
 			case <-time.After(backoff):
 			case <-ctx.Done():
@@ -35,13 +35,15 @@ func (a *Agent) runTunnel(ctx context.Context) {
 	}
 }
 
-func (a *Agent) tunnelOnce(ctx context.Context) error {
+func (a *Agent) tunnelOnce(ctx context.Context, addr string) error {
 	d := net.Dialer{Timeout: 10 * time.Second}
-	conn, err := d.DialContext(ctx, "tcp", a.cfg.TunnelAddr)
+	conn, err := d.DialContext(ctx, "tcp", addr)
 	if err != nil {
 		return err
 	}
 	defer conn.Close()
+	// Unblock the read loop when the tunnel is stopped or moved.
+	defer context.AfterFunc(ctx, func() { conn.Close() })()
 	if tc, ok := conn.(*net.TCPConn); ok {
 		_ = tc.SetNoDelay(true)
 	}
@@ -65,7 +67,7 @@ func (a *Agent) tunnelOnce(ctx context.Context) error {
 		return err
 	}
 	_ = conn.SetDeadline(time.Time{})
-	log.Printf("tunnel: connected to %s", a.cfg.TunnelAddr)
+	log.Printf("tunnel: connected to %s", addr)
 
 	tc := &tunClient{conn: conn, streams: map[uint32]*agentStream{}}
 	return tc.readLoop()
@@ -194,12 +196,12 @@ func (t *tunClient) shutdown() {
 
 // --- direct UDP forwarding ---
 
-// runUDP maintains the agent's UDP endpoint on the host's 8446 channel and
+// runUDP maintains the agent's UDP endpoint on the host's tunnel at addr and
 // relays datagrams to/from client-side UDP ports for "udp" forward rules.
-func (a *Agent) runUDP(ctx context.Context) {
+func (a *Agent) runUDP(ctx context.Context, addr string) {
 	backoff := time.Second
 	for ctx.Err() == nil {
-		if err := a.udpOnce(ctx); err != nil {
+		if err := a.udpOnce(ctx, addr); err != nil {
 			select {
 			case <-time.After(backoff):
 			case <-ctx.Done():
@@ -214,8 +216,8 @@ func (a *Agent) runUDP(ctx context.Context) {
 	}
 }
 
-func (a *Agent) udpOnce(ctx context.Context) error {
+func (a *Agent) udpOnce(ctx context.Context, addr string) error {
-	raddr, err := net.ResolveUDPAddr("udp", a.cfg.TunnelAddr)
+	raddr, err := net.ResolveUDPAddr("udp", addr)
 	if err != nil {
 		return err
 	}
@@ -224,6 +226,8 @@ func (a *Agent) udpOnce(ctx context.Context) error {
 		return err
 	}
 	defer conn.Close()
+	// Unblock the read loop when the tunnel is stopped or moved.
+	defer context.AfterFunc(ctx, func() { conn.Close() })()
 
 	key := tunnel.AuthKey(a.state.Token)
 	register := func() {
@@ -268,7 +272,7 @@ func (a *Agent) udpOnce(ctx context.Context) error {
 }
 
 type udpClient struct {
-	server *net.UDPConn // connection back to host:8446
+	server *net.UDPConn // connection back to the host tunnel
 	mu     sync.Mutex
 	dials  map[uint32]*net.UDPConn // sid -> client-side socket
 }

internal/proto/proto.go

@@ -91,6 +91,10 @@ const (
 	TaskSysUserAdd = "sys.useradd" // create a new OS user
 )
 
+// FSReadCap bounds how many bytes TaskFSRead returns (5 MiB). The panel lets a
+// file be edited only when it fits, so that a save never cuts it short.
+const FSReadCap = 5 * 1024 * 1024
+
 // TaskEnvelope is what the agent fetches for a task id.
 type TaskEnvelope struct {
 	Type string          `json:"type"`

internal/server/config.go

@@ -3,6 +3,9 @@ package server
 import (
 	"crypto/rand"
 	"encoding/hex"
+	"strconv"
+
+	lpra "github.com/x-grk/longpolling-remote-access"
 )
 
 // Config keys stored in the config table.
@@ -12,15 +15,17 @@ const (
 	cfgSetupDone    = "setup_done"
 	cfgInstallCode  = "install_code"
 	cfgUfwEnabled   = "ufw_enabled"
+	cfgTunnelHost   = "tunnel_host"
+	cfgTunnelPort   = "tunnel_port"
 )
 
 // DefaultHostAddress is the public URL agents dial by default. It is baked into
 // the rendered install.sh and can be changed from the settings page.
 const DefaultHostAddress = "https://REDACTED:8445"
 
-// Version is the server build version, injected at compile time via -ldflags
+// Version is the server build version (see VERSION.txt). It is the newest
-// (-X .../internal/server.Version=...). It is the newest version agents update to.
+// version agents update to.
-var Version = "dev"
+var Version = lpra.Version
 
 // ensureDefaults seeds the host address and a random enroll secret on first boot.
 func (db *DB) ensureDefaults() error {
@@ -86,6 +91,24 @@ func (db *DB) SetUfwEnabled(on bool) error {
 	return db.SetConfig(cfgUfwEnabled, "0")
 }
 
+// TunnelHost is the host agents dial for the direct tunnel. Empty means the
+// host of the URL they already reach the panel on.
+func (db *DB) TunnelHost() string {
+	v, _ := db.GetConfig(cfgTunnelHost)
+	return v
+}
+
+// TunnelPort is the direct-tunnel port set in Settings, or 0 when it is left
+// at the port of the server's -tunnel address.
+func (db *DB) TunnelPort() int {
+	v, _ := db.GetConfig(cfgTunnelPort)
+	n, _ := strconv.Atoi(v)
+	if n < 1 || n > 65535 {
+		return 0
+	}
+	return n
+}
+
 func (db *DB) SetupDone() bool {
 	v, _ := db.GetConfig(cfgSetupDone)
 	return v == "1"

internal/server/handlers_agent.go

@@ -52,7 +52,31 @@ func (s *Server) handlePoll(w http.ResponseWriter, r *http.Request) {
 	} else {
 		_ = s.db.TouchAgent(a.ID)
 	}
-	writeJSON(w, s.hub.WaitControl(a.ID, pollHold))
+	msg := s.hub.WaitControl(a.ID, pollHold)
+	// Set after the hold so a port changed meanwhile reaches the agent now.
+	s.setTunnelHeader(w)
+	writeJSON(w, msg)
+}
+
+// tunnelAddrHeader carries the direct-tunnel address ("host:port", host empty
+// = the panel's host) to agents, on every poll and on /api/agent/config.
+const tunnelAddrHeader = "X-Tunnel-Addr"
+
+func (s *Server) setTunnelHeader(w http.ResponseWriter) {
+	if addr := s.tunnelAdvert(); addr != "" {
+		w.Header().Set(tunnelAddrHeader, addr)
+	}
+}
+
+// GET /api/agent/config — settings an agent picks up when it connects, without
+// waiting out a poll hold.
+func (s *Server) handleAgentConfig(w http.ResponseWriter, r *http.Request) {
+	if s.authenticateAgent(r) == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	s.setTunnelHeader(w)
+	w.WriteHeader(http.StatusNoContent)
 }
 
 // GET /api/agent/task/{id} — the agent fetches the task to run.

internal/server/handlers_panel.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"log"
+	"net"
 	"net/http"
 	"net/url"
 	"slices"
@@ -349,9 +350,76 @@ func (s *Server) handleSettings(w http.ResponseWriter, r *http.Request) {
 		"UfwRunnable":   ufwRunnable,
 		"UfwEnabled":    s.db.UfwEnabled(),
 		"UfwRules":      ufwRules,
+		"UfwError":      s.ufw.LastError(),
+		"TunnelPort":    s.TunnelPort(),
+		"TunnelDefault": s.tunnelDefault,
+		"TunnelHost":    s.db.TunnelHost(),
+		"TunnelCustom":  s.db.TunnelPort() > 0,
+		"Error": map[string]string{
+			"tunnel_host":   "Некорректный хост туннеля: нужен IP или имя без схемы и порта.",
+			"tunnel_port":   "Некорректный порт туннеля.",
+			"tunnel_listen": "Не удалось занять новый порт туннеля на хосте (возможно, уже используется). Порт не изменён.",
+		}[r.URL.Query().Get("err")],
 	})
 }
 
+// POST /settings/tunnel — host and port agents use for the direct tunnel.
+func (s *Server) handleSetTunnel(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	if s.tunnelDefault == 0 {
+		http.Redirect(w, r, "/settings", http.StatusSeeOther)
+		return
+	}
+	host := strings.TrimSpace(r.FormValue("tunnel_host"))
+	host = strings.TrimSuffix(strings.TrimPrefix(host, "["), "]")
+	if !validTunnelHost(host) {
+		http.Redirect(w, r, "/settings?err=tunnel_host", http.StatusSeeOther)
+		return
+	}
+	// An empty port goes back to the one the server was started with.
+	port, custom := s.tunnelDefault, ""
+	if v := strings.TrimSpace(r.FormValue("tunnel_port")); v != "" {
+		n, err := strconv.Atoi(v)
+		if err != nil || n < 1 || n > 65535 {
+			http.Redirect(w, r, "/settings?err=tunnel_port", http.StatusSeeOther)
+			return
+		}
+		port = n
+		if n != s.tunnelDefault {
+			custom = v
+		}
+	}
+	if err := s.setTunnelPort(port); err != nil {
+		log.Printf("tunnel: move to port %d: %v", port, err)
+		http.Redirect(w, r, "/settings?err=tunnel_listen", http.StatusSeeOther)
+		return
+	}
+	_ = s.db.SetConfig(cfgTunnelPort, custom)
+	_ = s.db.SetConfig(cfgTunnelHost, host)
+	http.Redirect(w, r, "/settings", http.StatusSeeOther)
+}
+
+// validTunnelHost accepts an empty value, an IP, or a bare host name.
+func validTunnelHost(host string) bool {
+	if host == "" || net.ParseIP(host) != nil {
+		return true
+	}
+	if len(host) > 253 {
+		return false
+	}
+	for _, c := range host {
+		switch {
+		case c >= 'a' && c <= 'z', c >= 'A' && c <= 'Z', c >= '0' && c <= '9', c == '-', c == '.', c == '_':
+		default:
+			return false
+		}
+	}
+	return true
+}
+
 func (s *Server) handleSetHost(w http.ResponseWriter, r *http.Request) {
 	if !checkCSRF(r) {
 		http.Error(w, "bad csrf", http.StatusForbidden)
@@ -408,7 +476,12 @@ func (s *Server) handleUfwToggle(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "bad csrf", http.StatusForbidden)
 		return
 	}
-	_ = s.db.SetUfwEnabled(r.FormValue("enabled") == "1")
+	on := r.FormValue("enabled") == "1"
+	_ = s.db.SetUfwEnabled(on)
+	if on {
+		// Open what forwards created while the integration was off need.
+		s.ufw.sync()
+	}
 	http.Redirect(w, r, "/settings", http.StatusSeeOther)
 }
 

internal/server/handlers_panel_fs.go

@@ -34,7 +34,7 @@ func (s *Server) handleFilesPage(w http.ResponseWriter, r *http.Request) {
 		http.NotFound(w, r)
 		return
 	}
-	s.render(w, "files.html", map[string]any{"Agent": a})
+	s.render(w, "files.html", map[string]any{"Agent": a, "EditLimit": proto.FSReadCap})
 }
 
 // POST /api/panel/agents/{id}/fs/{op} — run a file-manager operation on the

internal/server/handlers_panel_fwd.go

@@ -3,6 +3,7 @@ package server
 import (
 	"log"
 	"net/http"
+	"net/url"
 	"strconv"
 	"strings"
 )
@@ -22,13 +23,30 @@ func (s *Server) handleForwardsPage(w http.ResponseWriter, r *http.Request) {
 		"db":     "Ошибка базы данных.",
 	}[r.URL.Query().Get("err")]
 	s.render(w, "forwards.html", map[string]any{
-		"Agent": a,
+		"Agent":      a,
-		"Rules": rules,
+		"Rules":      rules,
-		"CSRF":  csrfToken(r),
+		"CSRF":       csrfToken(r),
-		"Error": errMsg,
+		"Error":      errMsg,
+		"TunnelPort": s.TunnelPort(),
+		"PanelPort":  panelPort(s.db.HostAddress()),
 	})
 }
 
+// panelPort is the port of the panel URL agents dial, for the mode hints.
+func panelPort(host string) string {
+	u, err := url.Parse(host)
+	if err != nil {
+		return ""
+	}
+	if p := u.Port(); p != "" {
+		return p
+	}
+	if u.Scheme == "http" {
+		return "80"
+	}
+	return "443"
+}
+
 // POST /agents/{id}/forwards/add
 func (s *Server) handleForwardAdd(w http.ResponseWriter, r *http.Request) {
 	if !checkCSRF(r) {
@@ -57,8 +75,8 @@ func (s *Server) handleForwardAdd(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "/agents/"+id+"/forwards?err=port", http.StatusSeeOther)
 		return
 	}
-	// Reject a host port already bound by another forward rule.
+	// Reject a host port already bound by another forward rule or the tunnel.
-	if s.db.HostPortUsed(hostPort) {
+	if s.db.HostPortUsed(hostPort) || hostPort == s.TunnelPort() {
 		http.Redirect(w, r, "/agents/"+id+"/forwards?err=busy", http.StatusSeeOther)
 		return
 	}
@@ -91,7 +109,8 @@ func (s *Server) handleForwardDelete(w http.ResponseWriter, r *http.Request) {
 	rule, _ := s.db.GetForwardRule(rid)
 	s.fwd.close(rid)
 	_ = s.db.DeleteForwardRule(rid)
-	// Remove the ufw rule bound to this forward rule (shared 8446 stays).
+	// Remove the ufw rule bound to this forward rule (the shared tunnel port
+	// stays while another direct forward needs it).
 	s.ufw.revokeForRule(rid)
 	dest := "/"
 	if rule != nil {

internal/server/server.go

@@ -9,6 +9,8 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
+	"sync"
+	"sync/atomic"
 	texttemplate "text/template"
 )
 
@@ -24,7 +26,8 @@ type Options struct {
 	// nginx TLS); set false only for plain-HTTP local testing.
 	SecureCookies bool
 	// TunnelAddr is the listen address for the direct TCP+UDP forward tunnel
-	// (default ":8446"). Empty disables direct forwarding.
+	// (default ":8446"). Empty disables direct forwarding. The port can be
+	// overridden from the settings page.
 	TunnelAddr string
 }
 
@@ -33,12 +36,22 @@ type Server struct {
 	db            *DB
 	hub           *Hub
 	fwd           *forwardManager
+	tun           *tunnelHub
+	udp           *udpRelay
 	ufw           *ufwManager
 	tmpl          *template.Template
 	limiter       *loginLimiter
 	distDir       string
 	secureCookies bool
 	installTmpl   *texttemplate.Template
+
+	// Direct tunnel: bind host and port of the -tunnel address, and the port
+	// currently listened on (the settings override, else the default).
+	// tunnelDefault 0 means the tunnel is disabled.
+	tunnelBind    string
+	tunnelDefault int
+	tunnelMu      sync.Mutex // serializes port changes
+	tunnelPort    atomic.Int64
 }
 
 // New builds the server, parsing embedded templates.
@@ -65,26 +78,81 @@ func New(opts Options) (*Server, error) {
 		db:            opts.DB,
 		hub:           hub,
 		fwd:           newForwardManager(hub, tun, udp),
-		ufw:           newUfwManager(opts.DB, portFromAddr(opts.TunnelAddr)),
+		tun:           tun,
+		udp:           udp,
 		tmpl:          tmpl,
 		limiter:       newLoginLimiter(),
 		distDir:       opts.DistDir,
 		secureCookies: opts.SecureCookies,
 		installTmpl:   installTmpl,
 	}
-	// Start the direct forward tunnel (TCP mux + UDP) on 8446.
+	s.ufw = newUfwManager(opts.DB, s.TunnelPort)
+	// Start the direct forward tunnel (TCP mux + UDP), on the port from the
+	// settings page if one is set there.
 	if opts.TunnelAddr != "" {
-		if err := tun.listen(opts.TunnelAddr); err != nil {
+		s.tunnelBind, s.tunnelDefault = splitAddr(opts.TunnelAddr)
-			log.Printf("tunnel tcp listen %s: %v", opts.TunnelAddr, err)
+	}
+	if s.tunnelDefault > 0 {
+		port := s.tunnelDefault
+		if p := s.db.TunnelPort(); p > 0 {
+			port = p
 		}
-		if err := udp.listen(opts.TunnelAddr); err != nil {
+		s.tunnelPort.Store(int64(port))
-			log.Printf("tunnel udp listen %s: %v", opts.TunnelAddr, err)
+		addr := s.tunnelListenAddr(port)
+		if err := tun.listen(addr); err != nil {
+			log.Printf("tunnel tcp listen %s: %v", addr, err)
+		}
+		if err := udp.listen(addr); err != nil {
+			log.Printf("tunnel udp listen %s: %v", addr, err)
 		}
 	}
 	s.restoreForwards()
+	go s.ufw.sync()
 	return s, nil
 }
 
+// TunnelPort is the port the direct tunnel listens on (0 = disabled).
+func (s *Server) TunnelPort() int { return int(s.tunnelPort.Load()) }
+
+func (s *Server) tunnelListenAddr(port int) string {
+	return net.JoinHostPort(s.tunnelBind, strconv.Itoa(port))
+}
+
+// tunnelAdvert is the tunnel address handed to agents as "host:port". The host
+// is empty unless one is set in Settings; agents then use the panel's host.
+func (s *Server) tunnelAdvert() string {
+	port := s.TunnelPort()
+	if port == 0 {
+		return ""
+	}
+	return net.JoinHostPort(s.db.TunnelHost(), strconv.Itoa(port))
+}
+
+// setTunnelPort moves the direct tunnel to another port. Connected agents are
+// dropped and redial the new port once their next poll tells them about it.
+func (s *Server) setTunnelPort(port int) error {
+	s.tunnelMu.Lock()
+	defer s.tunnelMu.Unlock()
+	old := s.TunnelPort()
+	if old == 0 || port == old {
+		return nil
+	}
+	addr := s.tunnelListenAddr(port)
+	if err := s.tun.listen(addr); err != nil {
+		return err
+	}
+	if err := s.udp.listen(addr); err != nil {
+		// Keep TCP and UDP on the same port: go back to the old one.
+		if rerr := s.tun.listen(s.tunnelListenAddr(old)); rerr != nil {
+			log.Printf("tunnel tcp listen %s: %v", s.tunnelListenAddr(old), rerr)
+		}
+		return err
+	}
+	s.tunnelPort.Store(int64(port))
+	go s.ufw.sync()
+	return nil
+}
+
 // restoreForwards re-opens the host listeners for all saved forward rules.
 func (s *Server) restoreForwards() {
 	rules, err := s.db.ListForwardRules()
@@ -134,6 +202,7 @@ func (s *Server) Handler() http.Handler {
 	mux.Handle("POST /agents/{id}/delete", s.requireAdmin(s.handleAgentDelete))
 	mux.Handle("GET /settings", s.requireAdmin(s.handleSettings))
 	mux.Handle("POST /settings/host", s.requireAdmin(s.handleSetHost))
+	mux.Handle("POST /settings/tunnel", s.requireAdmin(s.handleSetTunnel))
 	mux.Handle("POST /settings/secret/rotate", s.requireAdmin(s.handleRotateSecret))
 	mux.Handle("POST /settings/admins/add", s.requireAdmin(s.handleAddAdmin))
 	mux.Handle("POST /settings/admins/delete", s.requireAdmin(s.handleDeleteAdmin))
@@ -157,6 +226,7 @@ func (s *Server) Handler() http.Handler {
 	// Agent API (token/secret auth inside handlers).
 	mux.HandleFunc("POST /api/agent/enroll", s.handleEnroll)
 	mux.HandleFunc("GET /api/agent/poll", s.handlePoll)
+	mux.HandleFunc("GET /api/agent/config", s.handleAgentConfig)
 	mux.HandleFunc("GET /api/agent/term/{sid}/in", s.handleTermIn)
 	mux.HandleFunc("POST /api/agent/term/{sid}/out", s.handleTermOut)
 	mux.HandleFunc("GET /api/agent/task/{id}", s.handleTaskFetch)
@@ -202,17 +272,15 @@ func (s *Server) render(w http.ResponseWriter, name string, data map[string]any)
 	}
 }
 
-// portFromAddr extracts the numeric port from a "host:port" or ":port" address.
+// splitAddr splits a "host:port" or ":port" listen address. The port is 0 when
-func portFromAddr(addr string) int {
+// the address has none.
-	if addr == "" {
+func splitAddr(addr string) (host string, port int) {
-		return 0
+	h, p, err := net.SplitHostPort(addr)
-	}
-	_, p, err := net.SplitHostPort(addr)
 	if err != nil {
-		return 0
+		return "", 0
 	}
 	n, _ := strconv.Atoi(p)
-	return n
+	return h, n
 }
 
 func clientIP(r *http.Request) string {

internal/server/tunnelserver.go

@@ -39,6 +39,7 @@ func readLine(r io.Reader, max int) (string, error) {
 type tunnelHub struct {
 	db     *DB
 	mu     sync.Mutex
+	ln     net.Listener
 	agents map[string]*agentTunnel
 }
 
@@ -57,12 +58,30 @@ type agentTunnel struct {
 	streams map[uint32]net.Conn
 }
 
-// listen runs the 8446 TCP tunnel acceptor until the listener closes.
+// listen runs the TCP tunnel acceptor until the listener closes. Listening
+// again moves the tunnel: the previous listener is closed and its agents are
+// dropped, so they redial the new address.
 func (h *tunnelHub) listen(addr string) error {
 	ln, err := net.Listen("tcp", addr)
 	if err != nil {
 		return err
 	}
+	h.mu.Lock()
+	old := h.ln
+	h.ln = ln
+	var stale []*agentTunnel
+	if old != nil {
+		for _, at := range h.agents {
+			stale = append(stale, at)
+		}
+	}
+	h.mu.Unlock()
+	if old != nil {
+		old.Close()
+	}
+	for _, at := range stale {
+		at.conn.Close()
+	}
 	log.Printf("tunnel: listening on %s (direct TCP forwarding)", addr)
 	go func() {
 		for {

internal/server/udp.go

@@ -20,9 +20,10 @@ import (
 //	registration (agent->server): "R <agentID> <sig>"
 //	data         (both):          'D' | sid(4) | port(2) | payload
 type udpRelay struct {
-	db   *DB
+	db     *DB
-	mu   sync.Mutex
+	mu     sync.Mutex
-	ctrl *net.UDPConn
+	ctrl   *net.UDPConn
+	gcOnce sync.Once
 
 	agentAddr map[string]*net.UDPAddr // agentID -> last registered addr
 	sessions  map[uint32]*udpSession
@@ -48,7 +49,8 @@ func newUDPRelay(db *DB) *udpRelay {
 	}
 }
 
-// listen opens the shared 8446 UDP control socket.
+// listen opens the shared UDP control socket. Listening again moves it: the
+// previous socket is closed and agents register anew on the new address.
 func (u *udpRelay) listen(addr string) error {
 	ua, err := net.ResolveUDPAddr("udp", addr)
 	if err != nil {
@@ -58,17 +60,26 @@ func (u *udpRelay) listen(addr string) error {
 	if err != nil {
 		return err
 	}
+	u.mu.Lock()
+	old := u.ctrl
 	u.ctrl = c
+	if old != nil {
+		u.agentAddr = map[string]*net.UDPAddr{}
+	}
+	u.mu.Unlock()
+	if old != nil {
+		old.Close()
+	}
 	log.Printf("tunnel: listening on %s/udp (direct UDP forwarding)", addr)
-	go u.ctrlLoop()
+	go u.ctrlLoop(c)
-	go u.gc()
+	u.gcOnce.Do(func() { go u.gc() })
 	return nil
 }
 
-func (u *udpRelay) ctrlLoop() {
+func (u *udpRelay) ctrlLoop(ctrl *net.UDPConn) {
 	buf := make([]byte, 65535)
 	for {
-		n, src, err := u.ctrl.ReadFromUDP(buf)
+		n, src, err := ctrl.ReadFromUDP(buf)
 		if err != nil {
 			return
 		}
@@ -171,6 +182,7 @@ func (u *udpRelay) rulePortLoop(rule ForwardRule, c *net.UDPConn) {
 		}
 		u.mu.Lock()
 		aAddr := u.agentAddr[rule.AgentID]
+		ctrl := u.ctrl
 		// Find existing session for this (rule, user).
 		var sess *udpSession
 		for _, s := range u.sessions {
@@ -190,7 +202,7 @@ func (u *udpRelay) rulePortLoop(rule ForwardRule, c *net.UDPConn) {
 		sess.last = time.Now()
 		u.mu.Unlock()
 
-		if aAddr == nil {
+		if aAddr == nil || ctrl == nil {
 			continue // agent has not registered its UDP endpoint yet
 		}
 		// 'D' | sid(4) | clientPort(2) | payload
@@ -199,7 +211,7 @@ func (u *udpRelay) rulePortLoop(rule ForwardRule, c *net.UDPConn) {
 		binary.BigEndian.PutUint32(out[1:5], sess.id)
 		binary.BigEndian.PutUint16(out[5:7], uint16(rule.ClientPort))
 		copy(out[7:], buf[:n])
-		_, _ = u.ctrl.WriteToUDP(out, aAddr)
+		_, _ = ctrl.WriteToUDP(out, aAddr)
 	}
 }
 

internal/server/ufw.go

@@ -3,8 +3,11 @@ package server
 import (
 	"fmt"
 	"log"
+	"net"
+	"os"
 	"os/exec"
 	"strings"
+	"sync"
 )
 
 // ufwManager integrates with the host firewall (ufw) when it is installed and
@@ -14,28 +17,40 @@ import (
 // ufw requires root, so this only works when the server process can run ufw
 // (e.g. running as root). When it cannot, integration is simply inactive.
 type ufwManager struct {
-	db         *DB
+	db *DB
-	tunnelPort int
+	// tunnelPort returns the current direct-tunnel port (0 = tunnel disabled).
+	tunnelPort func() int
+
+	mu      sync.Mutex
+	lastErr string // last failed ufw command, shown in Settings
 }
 
-func newUfwManager(db *DB, tunnelPort int) *ufwManager {
+func newUfwManager(db *DB, tunnelPort func() int) *ufwManager {
 	return &ufwManager{db: db, tunnelPort: tunnelPort}
 }
 
+// ufwRun runs ufw with a fixed C locale: its output is translated, and we
+// match on the English text.
+func ufwRun(args ...string) (string, error) {
+	cmd := exec.Command("ufw", args...)
+	cmd.Env = append(os.Environ(), "LC_ALL=C", "LANG=C", "LANGUAGE=C")
+	out, err := cmd.CombinedOutput()
+	return strings.TrimSpace(string(out)), err
+}
+
 // status reports whether ufw is installed, active, and runnable by this process.
 func (u *ufwManager) status() (installed, active, runnable bool) {
-	path, err := exec.LookPath("ufw")
+	if _, err := exec.LookPath("ufw"); err != nil {
-	if err != nil {
 		return false, false, false
 	}
 	installed = true
-	out, err := exec.Command(path, "status").CombinedOutput()
+	out, err := ufwRun("status")
 	if err != nil {
 		// Typically a permission error (not root) -> not runnable.
 		return true, false, false
 	}
 	runnable = true
-	active = strings.Contains(string(out), "Status: active")
+	active = strings.Contains(out, "Status: active")
 	return installed, active, runnable
 }
 
@@ -48,18 +63,36 @@ func (u *ufwManager) available() bool {
 	return installed && active && runnable
 }
 
-// allow opens port/proto in ufw (if integration is available) and records it,
+func (u *ufwManager) setErr(msg string) {
-// bound to the given forward rule id (0 = shared/manual).
+	u.mu.Lock()
+	u.lastErr = msg
+	u.mu.Unlock()
+}
+
+// LastError returns the last failed ufw command ("" when the last one worked).
+func (u *ufwManager) LastError() string {
+	u.mu.Lock()
+	defer u.mu.Unlock()
+	return u.lastErr
+}
+
+// allow opens port/proto in ufw and records it, bound to the given forward
+// rule id (0 = shared/manual). The caller has checked available().
 func (u *ufwManager) allow(port int, proto string, ruleID int64) {
-	if !u.available() {
-		return
-	}
 	if u.db.HasUfwRule(port, proto) {
 		return
 	}
 	spec := fmt.Sprintf("%d/%s", port, proto)
-	if out, err := exec.Command("ufw", "allow", spec).CombinedOutput(); err != nil {
+	out, err := ufwRun("allow", spec)
-		log.Printf("ufw allow %s: %v: %s", spec, err, strings.TrimSpace(string(out)))
+	if err != nil {
+		log.Printf("ufw allow %s: %v: %s", spec, err, out)
+		u.setErr(fmt.Sprintf("ufw allow %s: %v: %s", spec, err, out))
+		return
+	}
+	u.setErr("")
+	if strings.Contains(out, "Skipping") {
+		// The rule was there before the panel asked for it, so it is not ours
+		// to track (and later delete).
 		return
 	}
 	_ = u.db.AddUfwRule(port, proto, ruleID)
@@ -69,9 +102,11 @@ func (u *ufwManager) allow(port int, proto string, ruleID int64) {
 // revokeRule deletes one tracked ufw rule from ufw and the tracking table.
 func (u *ufwManager) revokeRule(r UfwRule) {
 	spec := fmt.Sprintf("%d/%s", r.Port, r.Proto)
-	if out, err := exec.Command("ufw", "delete", "allow", spec).CombinedOutput(); err != nil {
+	if out, err := ufwRun("delete", "allow", spec); err != nil {
-		log.Printf("ufw delete allow %s: %v: %s", spec, err, strings.TrimSpace(string(out)))
+		log.Printf("ufw delete allow %s: %v: %s", spec, err, out)
+		u.setErr(fmt.Sprintf("ufw delete allow %s: %v: %s", spec, err, out))
 	} else {
+		u.setErr("")
 		log.Printf("ufw: revoked %s", spec)
 	}
 	_ = u.db.DeleteUfwRule(r.ID)
@@ -86,8 +121,8 @@ func (u *ufwManager) revoke(id int64) {
 	u.revokeRule(*r)
 }
 
-// revokeForRule removes the ufw rules bound to a specific forward rule. The
+// revokeForRule removes the ufw rules bound to a specific forward rule, and
-// shared tunnel port (rule_id 0) is left alone, since other forwards use it.
+// the shared tunnel port once no forward needs it any more.
 func (u *ufwManager) revokeForRule(ruleID int64) {
 	rules, err := u.db.ListUfwRulesByRule(ruleID)
 	if err != nil {
@@ -96,24 +131,71 @@ func (u *ufwManager) revokeForRule(ruleID int64) {
 	for _, r := range rules {
 		u.revokeRule(r)
 	}
+	u.pruneShared()
+}
+
+// pruneShared revokes shared (rule_id 0) ufw rules that nothing uses: anything
+// but the current tunnel port, and the tunnel port itself for a protocol that
+// has no direct forward left.
+func (u *ufwManager) pruneShared() {
+	shared, err := u.db.ListUfwRulesByRule(0)
+	if err != nil || len(shared) == 0 {
+		return
+	}
+	forwards, err := u.db.ListForwardRules()
+	if err != nil {
+		return
+	}
+	used := map[string]bool{}
+	for _, f := range forwards {
+		used[f.Proto] = true
+	}
+	port := u.tunnelPort()
+	for _, r := range shared {
+		if r.Port != port || !used[r.Proto] {
+			u.revokeRule(r)
+		}
+	}
 }
 
 // allowForward opens the host ports a forward rule needs: its host port (bound
-// to the rule so it is revoked with it) plus the shared 8446 tunnel port for
+// to the rule so it is revoked with it) plus the shared tunnel port for direct
-// direct tcp/udp modes (bound to 0 — shared across rules).
+// tcp/udp modes (bound to 0 — shared across rules).
 func (u *ufwManager) allowForward(rule ForwardRule) {
-	switch rule.Proto {
+	if !u.available() {
-	case "udp":
+		return
-		u.allow(rule.HostPort, "udp", rule.ID)
+	}
-		if u.tunnelPort > 0 {
+	u.allowForwardPorts(rule)
-			u.allow(u.tunnelPort, "udp", 0)
+}
-		}
+
-	case "tcp":
+func (u *ufwManager) allowForwardPorts(rule ForwardRule) {
-		u.allow(rule.HostPort, "tcp", rule.ID)
+	// "http" (long-poll) and "tcp" forwards both listen on TCP on the host.
-		if u.tunnelPort > 0 {
+	hostProto, direct := "tcp", rule.Proto == "tcp"
-			u.allow(u.tunnelPort, "tcp", 0)
+	if rule.Proto == "udp" {
-		}
+		hostProto, direct = "udp", true
-	default: // http long-poll listener is TCP
+	}
-		u.allow(rule.HostPort, "tcp", rule.ID)
+	// A listener bound to loopback is not reachable from outside anyway.
+	if ip := net.ParseIP(rule.ListenAddr); ip == nil || !ip.IsLoopback() {
+		u.allow(rule.HostPort, hostProto, rule.ID)
+	}
+	if port := u.tunnelPort(); direct && port > 0 {
+		u.allow(port, hostProto, 0)
 	}
 }
+
+// sync brings ufw in line with the saved forward rules: it opens what is
+// missing (rules made while ufw or the integration was off, or a tunnel port
+// that has since changed) and drops shared rules nothing uses.
+func (u *ufwManager) sync() {
+	if !u.available() {
+		return
+	}
+	forwards, err := u.db.ListForwardRules()
+	if err != nil {
+		return
+	}
+	for _, f := range forwards {
+		u.allowForwardPorts(f)
+	}
+	u.pruneShared()
+}

internal/server/web/static/app.css

@@ -34,10 +34,14 @@ header.topbar nav a:hover { color: var(--text); }
 h1 { font-size: 22px; margin: 0 0 18px; }
 h2 { font-size: 17px; margin: 0 0 14px; }
 label { display: block; margin: 12px 0 4px; color: var(--muted); font-size: 13px; }
-input[type=text], input[type=password] {
+input[type=text], input[type=password], input[type=number] {
   width: 100%; padding: 10px 12px; border-radius: 8px;
   border: 1px solid var(--border); background: #0c0f13; color: var(--text); font-size: 14px;
 }
+/* No native spinner: it is drawn light and breaks the dark field. */
+input[type=number] { -moz-appearance: textfield; appearance: textfield; }
+input[type=number]::-webkit-inner-spin-button,
+input[type=number]::-webkit-outer-spin-button { -webkit-appearance: none; margin: 0; }
 /* Sized and shaped like .btn.ghost so it lines up with the buttons next to it. */
 select {
   -webkit-appearance: none; appearance: none; cursor: pointer;

internal/server/web/templates/files.html

@@ -107,7 +107,7 @@
     }).then(r => r.json()).catch(e => ({ok:false, error:'ошибка сети'})).finally(() => setBusy(false));
   };
 
-  const EDIT_LIMIT = 5 * 1024 * 1024;
+  const EDIT_LIMIT = {{.EditLimit}};
 
   // Monochrome inline icons (inherit button color via currentColor).
   const SVG = '<svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">';
@@ -190,10 +190,10 @@
       msg.textContent = 'Размер: '+fmtSize(d.size);
     } else {
       ta.value = new TextDecoder().decode(b64ToBytes(d.content));
-      const editable = d.size < EDIT_LIMIT && !d.truncated;
+      const editable = d.size <= EDIT_LIMIT && !d.truncated;
       ta.readOnly = !editable;
       save.style.display = editable ? '' : 'none';
-      msg.textContent = 'Размер: '+fmtSize(d.size) + (d.truncated?' · показано первые 5 МБ':'') + (editable?' · редактируемо':' · только чтение (≥ 5 МБ)');
+      msg.textContent = 'Размер: '+fmtSize(d.size) + (d.truncated?' · показано первые '+fmtSize(EDIT_LIMIT):'') + (editable?' · редактируемо':' · только чтение (больше '+fmtSize(EDIT_LIMIT)+')');
       save.onclick = async () => {
         const bytes = new TextEncoder().encode(ta.value);
         const w = await api('write', {path: join(cwd, e.name), data: bytesToB64(bytes)});

internal/server/web/templates/forwards.html

@@ -70,8 +70,8 @@
           <label>Тип</label>
           <select name="proto" id="proto">
             <option value="http">http (long-poll, работает везде)</option>
-            <option value="tcp">tcp (прямой, низкая задержка, порт 8446)</option>
+            <option value="tcp">tcp (прямой, низкая задержка, порт {{.TunnelPort}})</option>
-            <option value="udp">udp (прямой, порт 8446)</option>
+            <option value="udp">udp (прямой, порт {{.TunnelPort}})</option>
           </select>
         </div>
         <div class="fld">
@@ -95,18 +95,18 @@
   <div class="card">
     <h2>Режимы</h2>
     <ul class="muted" style="font-size:14px; line-height:1.7">
-      <li><b>http</b> — туннель поверх HTTP long-poll (через nginx :8445). Работает везде, где доступна панель, но задержка выше.</li>
+      <li><b>http</b> — туннель поверх HTTP long-poll (через адрес панели, порт {{.PanelPort}}). Работает везде, где доступна панель, но задержка выше.</li>
-      <li><b>tcp</b> — прямой TCP-мультиплексор через порт <b>8446</b> хоста. Минимальная задержка, keep-alive, TCP_NODELAY. Нужно открыть 8446/tcp на хосте.</li>
+      <li><b>tcp</b> — прямой TCP-мультиплексор через порт <b>{{.TunnelPort}}</b> хоста. Минимальная задержка, keep-alive, TCP_NODELAY. Нужно открыть {{.TunnelPort}}/tcp на хосте.</li>
-      <li><b>udp</b> — прямой UDP через порт <b>8446</b> хоста. Нужно открыть 8446/udp.</li>
+      <li><b>udp</b> — прямой UDP через порт <b>{{.TunnelPort}}</b> хоста. Нужно открыть {{.TunnelPort}}/udp.</li>
     </ul>
-    <p class="muted" style="font-size:13px">Для tcp/udp агент держит исходящее соединение к <code>host:8446</code>; несколько клиентов и портов мультиплексируются на нём.</p>
+    <p class="muted" style="font-size:13px">Для tcp/udp агент держит исходящее соединение к <code>host:{{.TunnelPort}}</code>; несколько клиентов и портов мультиплексируются на нём.</p>
   </div>
 </div>
 <script>
   var notes = {
-    http: 'Трафик идёт через :8445 (long-poll). Порт 8446 не требуется.',
+    http: 'Трафик идёт через порт панели {{.PanelPort}} (long-poll). Порт {{.TunnelPort}} не требуется.',
-    tcp:  'Требуется открытый порт 8446/tcp на хосте. Самая низкая задержка.',
+    tcp:  'Требуется открытый порт {{.TunnelPort}}/tcp на хосте. Самая низкая задержка.',
-    udp:  'Требуется открытый порт 8446/udp на хосте.'
+    udp:  'Требуется открытый порт {{.TunnelPort}}/udp на хосте.'
   };
   var sel = document.getElementById('proto'), note = document.getElementById('note');
   function upd(){ note.textContent = notes[sel.value] || ''; }

internal/server/web/templates/settings.html

@@ -19,6 +19,7 @@
 </header>
 <div class="wrap">
   <h1>Настройки</h1>
+  {{if .Error}}<div class="err">{{.Error}}</div>{{end}}
 
   <div class="card">
     <h2>Установка на новую машину</h2>
@@ -49,6 +50,26 @@
     </form>
   </div>
 
+  <div class="card">
+    <h2>Прямой туннель (tcp/udp проброс)</h2>
+    {{if not .TunnelDefault}}
+      <p class="muted">Прямой туннель отключён при запуске сервера (пустой <code>-tunnel</code> / <code>LPRA_TUNNEL_ADDR</code>).</p>
+    {{else}}
+      <p class="muted">Адрес, к которому агенты подключаются для проброса в режимах tcp/udp. Агенты забирают его
+        с панели сами — при подключении и при каждом опросе, так что смена применяется без переустановки.
+        Хост можно оставить пустым (тогда берётся хост из адреса панели) или указать IP/другое имя.</p>
+      <form method="post" action="/settings/tunnel" class="row">
+        <input type="hidden" name="csrf" value="{{.CSRF}}">
+        <input type="text" name="tunnel_host" value="{{.TunnelHost}}" placeholder="хост (как у панели)" style="max-width:260px">
+        <input type="number" name="tunnel_port" min="1" max="65535" value="{{if .TunnelCustom}}{{.TunnelPort}}{{end}}" placeholder="{{.TunnelDefault}}" style="max-width:120px">
+        <button type="submit">Сохранить</button>
+      </form>
+      <p class="muted" style="font-size:13px">Сейчас сервер слушает порт <b>{{.TunnelPort}}</b> (tcp и udp). При смене порта сервер
+        сразу начинает слушать новый, агенты переподключаются в течение ~30 секунд, правило ufw переносится.
+        Агенты старше 0.0.3 и агенты с заданными <code>TUNNEL_ADDR</code>/<code>TUNNEL_PORT</code> адрес с панели не берут.</p>
+    {{end}}
+  </div>
+
   <div class="card">
     <h2>Enroll-секрет</h2>
     <p class="muted">Общий секрет для регистрации новых агентов.</p>
@@ -103,7 +124,8 @@
         Статус ufw: {{if .UfwActive}}<span style="color:var(--ok)">активен</span>{{else}}<span style="color:var(--danger)">выключен</span>{{end}}
         · Интеграция: {{if .UfwEnabled}}<span style="color:var(--ok)">включена</span>{{else}}<span class="muted">выключена</span>{{end}}
       </p>
-      <p class="muted" style="font-size:13px">При создании правила проброса порт открывается в ufw автоматически (для tcp/udp — также порт 8446).</p>
+      <p class="muted" style="font-size:13px">При создании правила проброса порт открывается в ufw автоматически (для tcp/udp — также порт туннеля{{if .TunnelPort}} {{.TunnelPort}}{{end}}); для http-проброса открывается tcp-порт хоста. Порты правил, слушающих только 127.0.0.1, не открываются.</p>
+      {{if .UfwError}}<div class="err">Последняя команда ufw завершилась ошибкой: <code>{{.UfwError}}</code></div>{{end}}
       <form method="post" action="/settings/ufw/toggle" style="display:inline">
         <input type="hidden" name="csrf" value="{{.CSRF}}">
         <input type="hidden" name="enabled" value="{{if .UfwEnabled}}0{{else}}1{{end}}">

version.go

@@ -0,0 +1,14 @@
+// Package lpra holds what the server and the agent share at build time.
+package lpra
+
+import (
+	_ "embed"
+	"strings"
+)
+
+//go:embed VERSION.txt
+var versionFile string
+
+// Version is the release version of every binary in this module. VERSION.txt
+// is the only place it is defined.
+var Version = strings.TrimSpace(versionFile)