diff --git a/proxy/proxy.go b/proxy/proxy.go
index 3b0cdbd..ed23af7 100755
--- a/proxy/proxy.go
+++ b/proxy/proxy.go
@@ -8,6 +8,8 @@ import (
 
 	M "github.com/xjasonlyu/tun2socks/constant"
 	"github.com/xjasonlyu/tun2socks/proxy/proto"
+
+	"go.uber.org/atomic"
 )
 
 const (
@@ -15,7 +17,7 @@ const (
 )
 
 var (
-	_defaultDialer Dialer = &Base{}
+	_defaultDialer atomic.Value
 )
 
 type Dialer interface {
@@ -29,24 +31,28 @@ type Proxy interface {
 	Proto() proto.Proto
 }
 
+func init() {
+	_defaultDialer.Store(&Base{})
+}
+
 // SetDialer sets default Dialer.
 func SetDialer(d Dialer) {
-	_defaultDialer = d
+	_defaultDialer.Store(d)
 }
 
 // Dial uses default Dialer to dial TCP.
 func Dial(metadata *M.Metadata) (net.Conn, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), tcpConnectTimeout)
 	defer cancel()
-	return _defaultDialer.DialContext(ctx, metadata)
+	return _defaultDialer.Load().(Dialer).DialContext(ctx, metadata)
 }
 
 // DialContext uses default Dialer to dial TCP with context.
 func DialContext(ctx context.Context, metadata *M.Metadata) (net.Conn, error) {
-	return _defaultDialer.DialContext(ctx, metadata)
+	return _defaultDialer.Load().(Dialer).DialContext(ctx, metadata)
 }
 
 // DialUDP uses default Dialer to dial UDP.
 func DialUDP(metadata *M.Metadata) (net.PacketConn, error) {
-	return _defaultDialer.DialUDP(metadata)
+	return _defaultDialer.Load().(Dialer).DialUDP(metadata)
 }
diff --git a/tunnel/udp.go b/tunnel/udp.go
index f9bac4d..692a44d 100755
--- a/tunnel/udp.go
+++ b/tunnel/udp.go
@@ -14,6 +14,8 @@ import (
 	"github.com/xjasonlyu/tun2socks/log"
 	"github.com/xjasonlyu/tun2socks/proxy"
 	"github.com/xjasonlyu/tun2socks/tunnel/statistic"
+
+	"go.uber.org/atomic"
 )
 
 var (
@@ -23,11 +25,11 @@ var (
 
 	// _udpSessionTimeout is the default timeout for
 	// each UDP session.
-	_udpSessionTimeout = 60 * time.Second
+	_udpSessionTimeout = atomic.NewInt64(int64(60 * time.Second))
 )
 
 func SetUDPTimeout(v int) {
-	_udpSessionTimeout = time.Duration(v) * time.Second
+	_udpSessionTimeout.Store(int64(time.Duration(v) * time.Second))
 }
 
 func newUDPTracker(conn net.PacketConn, metadata *M.Metadata) net.PacketConn {
@@ -119,7 +121,7 @@ func handleUDPToRemote(packet core.UDPPacket, pc net.PacketConn, remote net.Addr
 	if _, err := pc.WriteTo(packet.Data() /* data */, remote); err != nil {
 		log.Warnf("[UDP] write to %s error: %v", remote, err)
 	}
-	pc.SetReadDeadline(time.Now().Add(_udpSessionTimeout)) /* reset timeout */
+	pc.SetReadDeadline(time.Now().Add(time.Duration(_udpSessionTimeout.Load()))) /* reset timeout */
 
 	log.Infof("[UDP] %s --> %s", packet.RemoteAddr(), remote)
 }
@@ -129,7 +131,7 @@ func handleUDPToLocal(packet core.UDPPacket, pc net.PacketConn) {
 	defer pool.Put(buf)
 
 	for /* just loop */ {
-		pc.SetReadDeadline(time.Now().Add(_udpSessionTimeout))
+		pc.SetReadDeadline(time.Now().Add(time.Duration(_udpSessionTimeout.Load())))
 		n, from, err := pc.ReadFrom(buf)
 		if err != nil {
 			if !errors.Is(err, os.ErrDeadlineExceeded) /* ignore i/o timeout */ {