diff --git a/common/cache/cache.go b/common/cache/cache.go
index d8a37ab..4f6033c 100644
--- a/common/cache/cache.go
+++ b/common/cache/cache.go
@@ -6,8 +6,10 @@ import (
 	"github.com/patrickmn/go-cache"
 )
 
+// The global cache
 var _cache = cache.New(30*time.Minute, 10*time.Minute)
 
+// GetCache returns the cache
 func GetCache() *cache.Cache {
 	return _cache
 }
diff --git a/common/cipher/cipher.go b/common/cipher/cipher.go
index e1012c5..4df7742 100644
--- a/common/cipher/cipher.go
+++ b/common/cipher/cipher.go
@@ -1,11 +1,14 @@
 package cipher
 
+// The default key
 var _key = []byte("vtun@2022")
 
+// SetKey sets the key
 func SetKey(key string) {
 	_key = []byte(key)
 }
 
+// XOR encrypts the data
 func XOR(src []byte) []byte {
 	_klen := len(_key)
 	for i := 0; i < len(src); i++ {
diff --git a/common/config/config.go b/common/config/config.go
index 205a8ca..2076cb3 100644
--- a/common/config/config.go
+++ b/common/config/config.go
@@ -1,5 +1,6 @@
 package config
 
+// The config struct
 type Config struct {
 	DeviceName                string
 	LocalAddr                 string
diff --git a/common/counter/counter.go b/common/counter/counter.go
index 91da45d..635bc0c 100644
--- a/common/counter/counter.go
+++ b/common/counter/counter.go
@@ -2,21 +2,28 @@ package counter
 
 import "sync/atomic"
 
+// totalReadBytes is the total number of bytes read
 var _totalReadBytes uint64 = 0
+
+// totalWrittenBytes is the total number of bytes written
 var _totalWrittenBytes uint64 = 0
 
+// IncrReadBytes increments the number of bytes read
 func IncrReadBytes(n int) {
 	atomic.AddUint64(&_totalReadBytes, uint64(n))
 }
 
+//IncrWrittenBytes increments the number of bytes written
 func IncrWrittenBytes(n int) {
 	atomic.AddUint64(&_totalWrittenBytes, uint64(n))
 }
 
+// GetReadBytes returns the number of bytes read
 func GetReadBytes() uint64 {
 	return _totalReadBytes
 }
 
+// GetWrittenBytes returns the number of bytes written
 func GetWrittenBytes() uint64 {
 	return _totalWrittenBytes
 }
diff --git a/common/netutil/netutil.go b/common/netutil/netutil.go
index 28d47e0..b5f0994 100644
--- a/common/netutil/netutil.go
+++ b/common/netutil/netutil.go
@@ -15,6 +15,7 @@ import (
 	"github.com/net-byte/vtun/common/config"
 )
 
+// ConnectServer connects to the server with the given address.
 func ConnectServer(config config.Config) net.Conn {
 	net.DefaultResolver = &net.Resolver{
 		PreferGo: true,
@@ -47,6 +48,7 @@ func ConnectServer(config config.Config) net.Conn {
 	return c
 }
 
+// GetInterfaceName returns the name of interface
 func GetInterface() (name string) {
 	ifaces := getAllInterfaces()
 	if len(ifaces) == 0 {
@@ -63,6 +65,7 @@ func GetInterface() (name string) {
 	return name
 }
 
+// getAllInterfaces returns all interfaces
 func getAllInterfaces() []net.Interface {
 	ifaces, err := net.Interfaces()
 	if err != nil {
@@ -82,6 +85,7 @@ func getAllInterfaces() []net.Interface {
 	return outInterfaces
 }
 
+// isPhysicalInterface returns true if the interface is physical
 func isPhysicalInterface(addr string) bool {
 	prefixArray := []string{"ens", "enp", "enx", "eno", "eth", "en0", "wlan", "wlp", "wlo", "wlx", "wifi0", "lan0"}
 	for _, pref := range prefixArray {
@@ -92,6 +96,7 @@ func isPhysicalInterface(addr string) bool {
 	return false
 }
 
+// Lookup IP address of the given hostname
 func LookupIP(domain string) net.IP {
 	ips, err := net.LookupIP(domain)
 	if err != nil || len(ips) == 0 {
@@ -101,32 +106,39 @@ func LookupIP(domain string) net.IP {
 	return ips[0]
 }
 
+// IsIPv4 returns true if the packet is IPv4s
 func IsIPv4(packet []byte) bool {
 	flag := packet[0] >> 4
 	return flag == 4
 }
 
+// IsIPv6 returns true if the packet is IPv6s
 func IsIPv6(packet []byte) bool {
 	flag := packet[0] >> 4
 	return flag == 6
 }
 
+// GetIPv4Src returns the IPv4 source address of the packet
 func GetIPv4Src(packet []byte) net.IP {
 	return net.IPv4(packet[12], packet[13], packet[14], packet[15])
 }
 
+// GEtIPv4Dst returns the IPv4 destination address of the packet
 func GetIPv4Dst(packet []byte) net.IP {
 	return net.IPv4(packet[16], packet[17], packet[18], packet[19])
 }
 
+// GetIPv6Src returns the IPv6 source address of the packet
 func GetIPv6Src(packet []byte) net.IP {
 	return net.IP(packet[8:24])
 }
 
+// GetIPv6Dst returns the IPv6 destination address of the packet
 func GetIPv6Dst(packet []byte) net.IP {
 	return net.IP(packet[24:40])
 }
 
+// GetSrcKey returns the source key of the packet
 func GetSrcKey(packet []byte) string {
 	key := ""
 	if IsIPv4(packet) && len(packet) >= 20 {
@@ -137,6 +149,7 @@ func GetSrcKey(packet []byte) string {
 	return key
 }
 
+// GetdstKey returns the destination key of the packets
 func GetDstKey(packet []byte) string {
 	key := ""
 	if IsIPv4(packet) && len(packet) >= 20 {
@@ -147,6 +160,7 @@ func GetDstKey(packet []byte) string {
 	return key
 }
 
+// ExecuteCommand executes the given command
 func ExecCmd(c string, args ...string) string {
 	log.Printf("exec cmd: %v %v:", c, args)
 	cmd := exec.Command(c, args...)
@@ -161,6 +175,7 @@ func ExecCmd(c string, args ...string) string {
 	return strings.ReplaceAll(s, "\n", "")
 }
 
+// GetLocalGatewayOnLinux returns the local gateway IP address on Linux
 func GetLocalGatewayOnLinux(ipv4 bool) string {
 	if ipv4 {
 		return ExecCmd("sh", "-c", "route -n | grep 'UG[ \t]' | awk 'NR==1{print $2}'")
@@ -168,6 +183,7 @@ func GetLocalGatewayOnLinux(ipv4 bool) string {
 	return ExecCmd("sh", "-c", "route -6 -n | grep 'UG[ \t]' | awk 'NR==1{print $2}'")
 }
 
+// GetLocalGatewayOnMac returns the local gateway IP address on MacOS
 func GetLocalGatewayOnMac(ipv4 bool) string {
 	if ipv4 {
 		return ExecCmd("sh", "-c", "route -n get default | grep 'gateway' | awk 'NR==1{print $2}'")
diff --git a/grpc/grpcclient.go b/grpc/grpcclient.go
index d46f62a..41c9d78 100644
--- a/grpc/grpcclient.go
+++ b/grpc/grpcclient.go
@@ -17,6 +17,7 @@ import (
 	"github.com/songgao/water"
 )
 
+// StartClient starts the grpc client
 func StartClient(config config.Config) {
 	log.Printf("vtun grpc client started on %v", config.LocalAddr)
 	iface := tun.CreateTun(config)
@@ -47,6 +48,7 @@ func StartClient(config config.Config) {
 	}
 }
 
+// tunToGrpc sends packets from tun to grpc
 func tunToGrpc(config config.Config, iface *water.Interface) {
 	packet := make([]byte, config.MTU)
 	for {
@@ -68,6 +70,7 @@ func tunToGrpc(config config.Config, iface *water.Interface) {
 	}
 }
 
+// grpcToTun sends packets from grpc to tun
 func grpcToTun(config config.Config, stream proto.GrpcServe_TunnelClient, iface *water.Interface) {
 	for {
 		packet, err := stream.Recv()
diff --git a/grpc/grpcserver.go b/grpc/grpcserver.go
index d63d4cd..2d6db10 100644
--- a/grpc/grpcserver.go
+++ b/grpc/grpcserver.go
@@ -17,17 +17,20 @@ import (
 	"github.com/songgao/water"
 )
 
+// The StreamService is the implementation of the StreamServer interface
 type StreamService struct {
 	proto.UnimplementedGrpcServeServer
 	config config.Config
 	iface  *water.Interface
 }
 
+// Tunnel implements the StreamServer interface
 func (s *StreamService) Tunnel(srv proto.GrpcServe_TunnelServer) error {
 	toServer(srv, s.config, s.iface)
 	return nil
 }
 
+// StartServer starts the grpc server
 func StartServer(config config.Config) {
 	log.Printf("vtun grpc server started on %v", config.LocalAddr)
 	iface := tun.CreateTun(config)
@@ -49,6 +52,7 @@ func StartServer(config config.Config) {
 	}
 }
 
+// toClient sends packets from tun to grpc
 func toClient(config config.Config, iface *water.Interface) {
 	packet := make([]byte, config.MTU)
 	for {
@@ -68,6 +72,7 @@ func toClient(config config.Config, iface *water.Interface) {
 	}
 }
 
+// toServer sends packets from grpc to tun
 func toServer(srv proto.GrpcServe_TunnelServer, config config.Config, iface *water.Interface) {
 	for {
 		packet, err := srv.Recv()
diff --git a/main.go b/main.go
index 9e0520c..842903a 100644
--- a/main.go
+++ b/main.go
@@ -52,6 +52,7 @@ func main() {
 	stopApp(config)
 }
 
+// initConfig initializes the config
 func initConfig(config *config.Config) {
 	if !config.ServerMode && config.GlobalMode {
 		host, _, err := net.SplitHostPort(config.ServerAddr)
@@ -71,6 +72,7 @@ func initConfig(config *config.Config) {
 	log.Printf("init config:%s", string(json))
 }
 
+// startApp starts the app
 func startApp(config config.Config) {
 	switch config.Protocol {
 	case "udp":
@@ -106,7 +108,8 @@ func startApp(config config.Config) {
 	}
 }
 
+// stopApp stops the app
 func stopApp(config config.Config) {
-	tun.Reset(config)
-	log.Printf("stopped!!!")
+	tun.ResetTun(config)
+	log.Printf("vtun stopped")
 }
diff --git a/register/register.go b/register/register.go
index 29adf7c..76fd6f6 100644
--- a/register/register.go
+++ b/register/register.go
@@ -9,25 +9,30 @@ import (
 	"github.com/patrickmn/go-cache"
 )
 
+// The global cache for register
 var _register *cache.Cache
 
 func init() {
 	_register = cache.New(30*time.Minute, 3*time.Minute)
 }
 
+// AddClientIP adds a client ip to the register
 func AddClientIP(ip string) {
 	_register.Add(ip, 0, cache.DefaultExpiration)
 }
 
+// DeleteClientIP deletes a client ip from the register
 func DeleteClientIP(ip string) {
 	_register.Delete(ip)
 }
 
+// ExistClientIP checks if the client ip is in the register
 func ExistClientIP(ip string) bool {
 	_, ok := _register.Get(ip)
 	return ok
 }
 
+// keepAlive keeps the client ip alive
 func KeepAliveClientIP(ip string) {
 	if ExistClientIP(ip) {
 		_register.Increment(ip, 1)
@@ -36,6 +41,7 @@ func KeepAliveClientIP(ip string) {
 	}
 }
 
+// PickClientIP picks a client ip from the register
 func PickClientIP(cidr string) (clientIP string, prefixLength string) {
 	ip, ipNet, err := net.ParseCIDR(cidr)
 	if err != nil {
@@ -59,7 +65,8 @@ func PickClientIP(cidr string) (clientIP string, prefixLength string) {
 	return "", ""
 }
 
-func ListClientIP() []string {
+// ListClientIPs returns the client ips in the register
+func ListClientIPs() []string {
 	result := []string{}
 	for k := range _register.Items() {
 		result = append(result, k)
@@ -67,11 +74,13 @@ func ListClientIP() []string {
 	return result
 }
 
+// addressCount returns the number of addresses in a CIDR network.
 func addressCount(network *net.IPNet) uint64 {
 	prefixLen, bits := network.Mask.Size()
 	return 1 << (uint64(bits) - uint64(prefixLen))
 }
 
+// incr increments the ip by 1
 func incr(IP net.IP) net.IP {
 	IP = checkIPv4(IP)
 	incIP := make([]byte, len(IP))
@@ -85,6 +94,7 @@ func incr(IP net.IP) net.IP {
 	return incIP
 }
 
+// checkIPv4 checks if the ip is IPv4
 func checkIPv4(ip net.IP) net.IP {
 	if v4 := ip.To4(); v4 != nil {
 		return v4
diff --git a/tls/tlsclient.go b/tls/tlsclient.go
index 435f308..64ffa29 100644
--- a/tls/tlsclient.go
+++ b/tls/tlsclient.go
@@ -14,7 +14,7 @@ import (
 	"github.com/songgao/water"
 )
 
-// Start tls client
+// StartClient starts the tls client
 func StartClient(config config.Config) {
 	log.Printf("vtun tls client started on %v", config.LocalAddr)
 	iface := tun.CreateTun(config)
@@ -37,6 +37,7 @@ func StartClient(config config.Config) {
 	}
 }
 
+// tunToTLS sends packets from tun to tls
 func tunToTLS(config config.Config, iface *water.Interface) {
 	packet := make([]byte, config.MTU)
 	for {
@@ -59,6 +60,7 @@ func tunToTLS(config config.Config, iface *water.Interface) {
 	}
 }
 
+// tlsToTun sends packets from tls to tun
 func tlsToTun(config config.Config, tlsconn net.Conn, iface *water.Interface) {
 	defer tlsconn.Close()
 	packet := make([]byte, config.MTU)
diff --git a/tls/tlsserver.go b/tls/tlsserver.go
index f0c2007..c8bb8df 100644
--- a/tls/tlsserver.go
+++ b/tls/tlsserver.go
@@ -15,7 +15,7 @@ import (
 	"github.com/songgao/water"
 )
 
-//Start tls server
+// StartServer starts the tls server
 func StartServer(config config.Config) {
 	log.Printf("vtun tls server started on %v", config.LocalAddr)
 	iface := tun.CreateTun(config)
@@ -51,6 +51,7 @@ func StartServer(config config.Config) {
 	}
 }
 
+// toClient sends packets from iface to tlsconn
 func toClient(config config.Config, iface *water.Interface) {
 	packet := make([]byte, config.MTU)
 	for {
@@ -70,7 +71,7 @@ func toClient(config config.Config, iface *water.Interface) {
 	}
 }
 
-// todo fallback to http
+// toServer sends packets from tlsconn to iface
 func toServer(config config.Config, tlsconn net.Conn, iface *water.Interface) {
 	defer tlsconn.Close()
 	packet := make([]byte, config.MTU)
diff --git a/tun/tun.go b/tun/tun.go
index 1ff123e..0f5fb2b 100644
--- a/tun/tun.go
+++ b/tun/tun.go
@@ -11,6 +11,7 @@ import (
 	"github.com/songgao/water"
 )
 
+// CreateTun creates a tun interface
 func CreateTun(config config.Config) (iface *water.Interface) {
 	c := water.Config{DeviceType: water.TUN}
 	if config.DeviceName != "" {
@@ -25,6 +26,7 @@ func CreateTun(config config.Config) (iface *water.Interface) {
 	return iface
 }
 
+// ConfigTun configures the tun interface
 func configTun(config config.Config, iface *water.Interface) {
 	os := runtime.GOOS
 	ip, _, err := net.ParseCIDR(config.CIDR)
@@ -91,7 +93,8 @@ func configTun(config config.Config, iface *water.Interface) {
 	}
 }
 
-func Reset(config config.Config) {
+// ResetTun resets the tun interface
+func ResetTun(config config.Config) {
 	os := runtime.GOOS
 	if os == "darwin" && !config.ServerMode && config.GlobalMode {
 		netutil.ExecCmd("route", "add", "default", config.LocalGateway)
diff --git a/udp/udpclient.go b/udp/udpclient.go
index 2ab6726..5e93797 100644
--- a/udp/udpclient.go
+++ b/udp/udpclient.go
@@ -12,7 +12,7 @@ import (
 	"golang.org/x/net/ipv6"
 )
 
-// Start udp client
+// StartClient starts the udp client
 func StartClient(config config.Config) {
 	log.Printf("vtun udp client started on %v", config.LocalAddr)
 	iface := tun.CreateTun(config)
@@ -45,6 +45,7 @@ func StartClient(config config.Config) {
 	c.tunToUdp()
 }
 
+// The client struct
 type Client struct {
 	config     config.Config
 	iface      *water.Interface
@@ -52,6 +53,7 @@ type Client struct {
 	serverAddr *net.UDPAddr
 }
 
+// udpToTun sends packets from udp to tun
 func (c *Client) udpToTun() {
 	packet := make([]byte, c.config.MTU)
 	for {
@@ -66,6 +68,8 @@ func (c *Client) udpToTun() {
 		c.iface.Write(b)
 	}
 }
+
+// tunToUdp sends packets from tun to udp
 func (c *Client) tunToUdp() {
 	packet := make([]byte, c.config.MTU)
 	for {
diff --git a/udp/udpserver.go b/udp/udpserver.go
index 781e5dc..289a8bb 100644
--- a/udp/udpserver.go
+++ b/udp/udpserver.go
@@ -15,7 +15,7 @@ import (
 	"golang.org/x/net/ipv6"
 )
 
-// Start udp server
+// StartServer starts the udp server
 func StartServer(config config.Config) {
 	log.Printf("vtun udp server started on %v", config.LocalAddr)
 	iface := tun.CreateTun(config)
@@ -44,6 +44,7 @@ func StartServer(config config.Config) {
 	s.udpToTun()
 }
 
+// the server struct
 type Server struct {
 	config    config.Config
 	iface     *water.Interface
@@ -51,6 +52,7 @@ type Server struct {
 	connCache *cache.Cache
 }
 
+// tunToUdp sends packets from tun to udp
 func (s *Server) tunToUdp() {
 	packet := make([]byte, s.config.MTU)
 	for {
@@ -70,6 +72,7 @@ func (s *Server) tunToUdp() {
 	}
 }
 
+// udpToTun sends packets from udp to tun
 func (s *Server) udpToTun() {
 	packet := make([]byte, s.config.MTU)
 	for {
diff --git a/ws/wsclient.go b/ws/wsclient.go
index 892b9fe..175a26b 100644
--- a/ws/wsclient.go
+++ b/ws/wsclient.go
@@ -14,7 +14,7 @@ import (
 	"github.com/songgao/water"
 )
 
-// Start websocket client
+// StartClient starts the ws client
 func StartClient(config config.Config) {
 	log.Printf("vtun websocket client started on %v", config.LocalAddr)
 	iface := tun.CreateTun(config)
@@ -31,6 +31,7 @@ func StartClient(config config.Config) {
 	}
 }
 
+// wsToTun sends packets from ws to tun
 func wsToTun(config config.Config, wsconn net.Conn, iface *water.Interface) {
 	defer wsconn.Close()
 	for {
@@ -49,6 +50,7 @@ func wsToTun(config config.Config, wsconn net.Conn, iface *water.Interface) {
 	}
 }
 
+// tunToWs sends packets from tun to ws
 func tunToWs(config config.Config, iface *water.Interface) {
 	packet := make([]byte, config.MTU)
 	for {
diff --git a/ws/wsserver.go b/ws/wsserver.go
index a1b0db2..a21436f 100644
--- a/ws/wsserver.go
+++ b/ws/wsserver.go
@@ -22,7 +22,7 @@ import (
 	"github.com/songgao/water"
 )
 
-// Start websocket server
+// StartServer starts the ws server
 func StartServer(config config.Config) {
 	iface := tun.CreateTun(config)
 	// server -> client
@@ -88,7 +88,7 @@ func StartServer(config config.Config) {
 		if !checkPermission(w, r, config) {
 			return
 		}
-		io.WriteString(w, strings.Join(register.ListClientIP(), "\r\n"))
+		io.WriteString(w, strings.Join(register.ListClientIPs(), "\r\n"))
 	})
 
 	http.HandleFunc("/register/prefix/ipv4", func(w http.ResponseWriter, r *http.Request) {
@@ -132,6 +132,8 @@ func StartServer(config config.Config) {
 	}
 
 }
+
+// checkPermission checks the permission of the request
 func checkPermission(w http.ResponseWriter, req *http.Request, config config.Config) bool {
 	key := req.Header.Get("key")
 	if key != config.Key {
@@ -142,6 +144,7 @@ func checkPermission(w http.ResponseWriter, req *http.Request, config config.Con
 	return true
 }
 
+// toClient sends data to client
 func toClient(config config.Config, iface *water.Interface) {
 	packet := make([]byte, config.MTU)
 	for {
@@ -162,6 +165,7 @@ func toClient(config config.Config, iface *water.Interface) {
 	}
 }
 
+// toServer sends data to server
 func toServer(config config.Config, wsconn net.Conn, iface *water.Interface) {
 	defer wsconn.Close()
 	for {