diff --git a/README.md b/README.md
index ad6b117..f7ec473 100644
--- a/README.md
+++ b/README.md
@@ -377,7 +377,7 @@ glider -config CONFIGPATH -listen :8080 -verbose
 
 ## Customize Build
 
-You can customize and build glider by yourself if you want a smaller binary.
+You can customize and build glider if you want a smaller binary.
 
 1. Clone the source code:
   ```bash
@@ -385,8 +385,8 @@ You can customize and build glider by yourself if you want a smaller binary.
   ```
 2. Customize features:
 
-  ```open `feature.go` & `feature_linux.go`, comment out the packages you don't need```
   ```bash
+  open `feature.go` & `feature_linux.go`, comment out the packages you don't need
   // _ "github.com/nadoo/glider/proxy/kcp"
   ```
 
diff --git a/go.mod b/go.mod
index 3856c88..0106610 100644
--- a/go.mod
+++ b/go.mod
@@ -10,10 +10,10 @@ require (
 	github.com/nadoo/ipset v0.3.0
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
 	github.com/xtaci/kcp-go/v5 v5.5.17
-	golang.org/x/crypto v0.0.0-20200930160638-afb6bcd081ae
+	golang.org/x/crypto v0.0.0-20201002094018-c90954cbb977
 	golang.org/x/net v0.0.0-20200930145003-4acb6c075d10 // indirect
 	golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f // indirect
-	golang.org/x/tools v0.0.0-20201001104356-43ebab892c4c // indirect
+	golang.org/x/tools v0.0.0-20201002055958-0d28ed0cbe40 // indirect
 	gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b // indirect
 )
 
diff --git a/go.sum b/go.sum
index b010fc2..577158a 100644
--- a/go.sum
+++ b/go.sum
@@ -118,8 +118,8 @@ golang.org/x/crypto v0.0.0-20200604202706-70a84ac30bf9/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20200728195943-123391ffb6de h1:ikNHVSjEfnvz6sxdSPCaPt572qowuyMDMJLLm3Db3ig=
 golang.org/x/crypto v0.0.0-20200728195943-123391ffb6de/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
-golang.org/x/crypto v0.0.0-20200930160638-afb6bcd081ae h1:duLSQW+DZ5MsXKX7kc4rXlq6/mmxz4G6ewJuBPlhRe0=
-golang.org/x/crypto v0.0.0-20200930160638-afb6bcd081ae/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20201002094018-c90954cbb977 h1:yH6opeNE+0SY+7pXT4gclZUoKHogXeC2EvOSHGOMGPU=
+golang.org/x/crypto v0.0.0-20201002094018-c90954cbb977/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/mod v0.2.0 h1:KU7oHjnv3XNWfa5COkzUifxZmxp1TyI7ImMXqFxLwvQ=
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
@@ -173,8 +173,8 @@ golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtn
 golang.org/x/tools v0.0.0-20200425043458-8463f397d07c h1:iHhCR0b26amDCiiO+kBguKZom9aMF+NrFxh9zeKR/XU=
 golang.org/x/tools v0.0.0-20200425043458-8463f397d07c/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
 golang.org/x/tools v0.0.0-20200808161706-5bf02b21f123/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
-golang.org/x/tools v0.0.0-20201001104356-43ebab892c4c h1:9BSeO6440XJVa2mxIcRAndAol4g4g2KflCVGcHx9Yu8=
-golang.org/x/tools v0.0.0-20201001104356-43ebab892c4c/go.mod h1:z6u4i615ZeAfBE4XtMziQW1fSVJXACjjbWkB/mvPzlU=
+golang.org/x/tools v0.0.0-20201002055958-0d28ed0cbe40 h1:ErPN1Z9An7dXc56pRUCKgWJkjYzc3hE+y15ky9E8qxU=
+golang.org/x/tools v0.0.0-20201002055958-0d28ed0cbe40/go.mod h1:z6u4i615ZeAfBE4XtMziQW1fSVJXACjjbWkB/mvPzlU=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
diff --git a/proxy/ss/ss.go b/proxy/ss/ss.go
index 5a53efa..193e09b 100644
--- a/proxy/ss/ss.go
+++ b/proxy/ss/ss.go
@@ -172,14 +172,14 @@ func (s *SS) Serve(c net.Conn) {
 func (s *SS) ListenAndServeUDP() {
 	lc, err := net.ListenPacket("udp", s.addr)
 	if err != nil {
-		log.F("[ss-udp] failed to listen on %s: %v", s.addr, err)
+		log.F("[ssu] failed to listen on %s: %v", s.addr, err)
 		return
 	}
 	defer lc.Close()
 
 	lc = s.PacketConn(lc)
 
-	log.F("[ss-udp] listening UDP on %s", s.addr)
+	log.F("[ssu] listening UDP on %s", s.addr)
 
 	var nm sync.Map
 	buf := make([]byte, proxy.UDPBufSize)
@@ -189,7 +189,7 @@ func (s *SS) ListenAndServeUDP() {
 
 		n, raddr, err := c.ReadFrom(buf)
 		if err != nil {
-			log.F("[ss-udp] remote read error: %v", err)
+			log.F("[ssu] remote read error: %v", err)
 			continue
 		}
 
@@ -198,7 +198,7 @@ func (s *SS) ListenAndServeUDP() {
 		if !ok && v == nil {
 			lpc, nextHop, err := s.proxy.DialUDP("udp", c.tgtAddr.String())
 			if err != nil {
-				log.F("[ss-udp] remote dial error: %v", err)
+				log.F("[ssu] remote dial error: %v", err)
 				continue
 			}
 
@@ -211,7 +211,7 @@ func (s *SS) ListenAndServeUDP() {
 				nm.Delete(raddr.String())
 			}()
 
-			log.F("[ss-udp] %s <-> %s", raddr, c.tgtAddr)
+			log.F("[ssu] %s <-> %s", raddr, c.tgtAddr)
 
 		} else {
 			pc = v.(*PktConn)
@@ -219,11 +219,11 @@ func (s *SS) ListenAndServeUDP() {
 
 		_, err = pc.WriteTo(buf[:n], pc.writeAddr)
 		if err != nil {
-			log.F("[ss-udp] remote write error: %v", err)
+			log.F("[ssu] remote write error: %v", err)
 			continue
 		}
 
-		// log.F("[ss-udp] %s <-> %s", raddr, c.tgtAddr)
+		// log.F("[ssu] %s <-> %s", raddr, c.tgtAddr)
 	}
 }
 
diff --git a/proxy/trojan/packet.go b/proxy/trojan/packet.go
index 309623d..5bf5910 100644
--- a/proxy/trojan/packet.go
+++ b/proxy/trojan/packet.go
@@ -28,6 +28,7 @@ func NewPktConn(c net.Conn, tgtAddr socks.Addr) *PktConn {
 }
 
 // ReadFrom implements the necessary function of net.PacketConn.
+// TODO: we know that we use it in proxy.RelayUDP and the length of b is enough, check it later.
 func (pc *PktConn) ReadFrom(b []byte) (int, net.Addr, error) {
 	// ATYP, DST.ADDR, DST.PORT
 	_, err := socks.ReadAddr(pc.Conn)
@@ -50,6 +51,10 @@ func (pc *PktConn) ReadFrom(b []byte) (int, net.Addr, error) {
 		return 0, nil, err
 	}
 
+	if len(b) < length {
+		return 0, nil, errors.New("buf size is not enough")
+	}
+
 	// Payload
 	n, err := io.ReadFull(pc.Conn, b[:length])
 	if err != nil {
@@ -69,5 +74,6 @@ func (pc *PktConn) WriteTo(b []byte, addr net.Addr) (int, error) {
 	binary.Write(buf, binary.BigEndian, uint16(len(b)))
 	buf.WriteString("\r\n")
 	buf.Write(b)
+
 	return pc.Write(buf.Bytes())
 }
diff --git a/proxy/vless/client.go b/proxy/vless/client.go
index e4233a3..6775fda 100644
--- a/proxy/vless/client.go
+++ b/proxy/vless/client.go
@@ -27,8 +27,8 @@ type Conn struct {
 	rcved bool
 }
 
-// NewConn returns a new vless client conn.
-func NewConn(c net.Conn, uuid [16]byte, target string) (*Conn, error) {
+// ClientConn returns a new vless client conn.
+func ClientConn(c net.Conn, uuid [16]byte, network, target string) (*Conn, error) {
 	atyp, addr, port, err := ParseAddr(target)
 	if err != nil {
 		return nil, err
@@ -40,7 +40,12 @@ func NewConn(c net.Conn, uuid [16]byte, target string) (*Conn, error) {
 	buf.WriteByte(Version) // ver
 	buf.Write(uuid[:])     // uuid
 	buf.WriteByte(0)       // addLen
-	buf.WriteByte(CmdTCP)  // cmd
+
+	cmd := CmdTCP
+	if network == "udp" {
+		cmd = CmdUDP
+	}
+	buf.WriteByte(cmd) // cmd
 
 	// target
 	err = binary.Write(buf, binary.BigEndian, uint16(port)) // port
diff --git a/proxy/vless/packet.go b/proxy/vless/packet.go
new file mode 100644
index 0000000..c649f61
--- /dev/null
+++ b/proxy/vless/packet.go
@@ -0,0 +1,53 @@
+package vless
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+	"net"
+
+	"github.com/nadoo/glider/pool"
+)
+
+// PktConn .
+type PktConn struct {
+	net.Conn
+}
+
+// NewPktConn returns a PktConn.
+func NewPktConn(c net.Conn) *PktConn {
+	return &PktConn{Conn: c}
+}
+
+// ReadFrom implements the necessary function of net.PacketConn.
+// TODO: we know that we use it in proxy.RelayUDP and the length of b is enough, check it later.
+func (pc *PktConn) ReadFrom(b []byte) (int, net.Addr, error) {
+	// Length
+	if _, err := io.ReadFull(pc.Conn, b[:2]); err != nil {
+		return 0, nil, err
+	}
+	length := int(binary.BigEndian.Uint16(b[:2]))
+
+	if len(b) < length {
+		return 0, nil, errors.New("buf size is not enough")
+	}
+
+	// Payload
+	n, err := io.ReadFull(pc.Conn, b[:length])
+	if err != nil {
+		return 0, nil, err
+	}
+
+	return n, nil, nil
+}
+
+// WriteTo implements the necessary function of net.PacketConn.
+func (pc *PktConn) WriteTo(b []byte, addr net.Addr) (int, error) {
+	buf := pool.GetWriteBuffer()
+	defer pool.PutWriteBuffer(buf)
+
+	binary.Write(buf, binary.BigEndian, uint16(len(b)))
+	buf.Write(b)
+
+	return pc.Write(buf.Bytes())
+}
diff --git a/proxy/vless/vless.go b/proxy/vless/vless.go
index 972eb95..6c18a96 100644
--- a/proxy/vless/vless.go
+++ b/proxy/vless/vless.go
@@ -1,7 +1,6 @@
 package vless
 
 import (
-	"errors"
 	"net"
 	"net/url"
 
@@ -60,10 +59,15 @@ func (s *VLess) Dial(network, addr string) (net.Conn, error) {
 	if err != nil {
 		return nil, err
 	}
-	return NewConn(rc, s.uuid, addr)
+	return ClientConn(rc, s.uuid, network, addr)
 }
 
 // DialUDP connects to the given address via the proxy.
 func (s *VLess) DialUDP(network, addr string) (net.PacketConn, net.Addr, error) {
-	return nil, nil, errors.New("vless client does not support udp now")
+	c, err := s.Dial("udp", addr)
+	if err != nil {
+		return nil, nil, err
+	}
+	pkc := NewPktConn(c)
+	return pkc, nil, nil
 }
diff --git a/proxy/vmess/client.go b/proxy/vmess/client.go
index e4a4e23..cc48e56 100644
--- a/proxy/vmess/client.go
+++ b/proxy/vmess/client.go
@@ -14,8 +14,9 @@ import (
 	"strings"
 	"time"
 
-	"github.com/nadoo/glider/pool"
 	"golang.org/x/crypto/chacha20poly1305"
+
+	"github.com/nadoo/glider/pool"
 )
 
 // Request Options
diff --git a/rule/group.go b/rule/group.go
index c2dcbd7..c8bbad4 100644
--- a/rule/group.go
+++ b/rule/group.go
@@ -226,9 +226,8 @@ func checkWebSite(fwdr *Forwarder, website string, timeout time.Duration, buf []
 
 	rc, err := fwdr.Dial("tcp", website)
 	if err != nil {
+		log.F("[check] %s(%d) -> %s, FAILED. error in dial: %s", fwdr.Addr(), fwdr.Priority(), website, err)
 		fwdr.Disable()
-		log.F("[check] %s(%d) -> %s, FAILED. error in dial: %s", fwdr.Addr(), fwdr.Priority(),
-			website, err)
 		return false
 	}
 	defer rc.Close()
@@ -239,24 +238,21 @@ func checkWebSite(fwdr *Forwarder, website string, timeout time.Duration, buf []
 
 	_, err = io.WriteString(rc, "GET / HTTP/1.0\r\n\r\n")
 	if err != nil {
+		log.F("[check] %s(%d) -> %s, FAILED. error in write: %s", fwdr.Addr(), fwdr.Priority(), website, err)
 		fwdr.Disable()
-		log.F("[check] %s(%d) -> %s, FAILED. error in write: %s", fwdr.Addr(), fwdr.Priority(),
-			website, err)
 		return false
 	}
 
 	_, err = io.ReadFull(rc, buf)
 	if err != nil {
+		log.F("[check] %s(%d) -> %s, FAILED. error in read: %s", fwdr.Addr(), fwdr.Priority(), website, err)
 		fwdr.Disable()
-		log.F("[check] %s(%d) -> %s, FAILED. error in read: %s", fwdr.Addr(), fwdr.Priority(),
-			website, err)
 		return false
 	}
 
 	if !bytes.Equal([]byte("HTTP"), buf) {
+		log.F("[check] %s(%d) -> %s, FAILED. server response: %s", fwdr.Addr(), fwdr.Priority(), website, buf)
 		fwdr.Disable()
-		log.F("[check] %s(%d) -> %s, FAILED. server response: %s", fwdr.Addr(), fwdr.Priority(),
-			website, buf)
 		return false
 	}
 
@@ -264,15 +260,13 @@ func checkWebSite(fwdr *Forwarder, website string, timeout time.Duration, buf []
 	fwdr.SetLatency(int64(readTime))
 
 	if readTime > timeout {
+		log.F("[check] %s(%d) -> %s, FAILED. check timeout: %s", fwdr.Addr(), fwdr.Priority(), website, readTime)
 		fwdr.Disable()
-		log.F("[check] %s(%d) -> %s, FAILED. check timeout: %s", fwdr.Addr(), fwdr.Priority(),
-			website, readTime)
 		return false
 	}
 
+	log.F("[check] %s(%d) -> %s, SUCCESS. elapsed time: %s", fwdr.Addr(), fwdr.Priority(), website, readTime)
 	fwdr.Enable()
-	log.F("[check] %s(%d) -> %s, SUCCESS. connect time: %s", fwdr.Addr(), fwdr.Priority(),
-		website, readTime)
 
 	return true
 }