diff --git a/common/ciphers/ssaead/cipher_packet.go b/common/ciphers/ssaead/cipher_packet.go
index f9474d2..d20cd13 100644
--- a/common/ciphers/ssaead/cipher_packet.go
+++ b/common/ciphers/ssaead/cipher_packet.go
@@ -38,7 +38,7 @@ func GetAEADPacketCiphers(method string) func(string, net.PacketConn) (net.Packe
 			PacketConn:  packCon,
 			IAEADCipher: c,
 			key:         evpBytesToKey(password, c.KeySize()),
-			buf:         pool.GetUdpBuf(),
+			buf:         pool.GetBuf(),
 		}
 		return ap, nil
 	}
diff --git a/common/ciphers/ssstream/cipher_packet.go b/common/ciphers/ssstream/cipher_packet.go
index d841fbd..26e3423 100644
--- a/common/ciphers/ssstream/cipher_packet.go
+++ b/common/ciphers/ssstream/cipher_packet.go
@@ -86,13 +86,13 @@ func (c *streamPacket) ReadFrom(b []byte) (n int, addr net.Addr, err error) {
 		return n, addr, err
 	}
 
-	pool.GetUdpBuf()
+	pool.GetBuf()
 	decryptr.XORKeyStream(b[ivLen:], b[ivLen:ivLen+n])
 	copy(b, b[ivLen:])
 	return n - ivLen, addr, err
 }
 
 func (c *streamPacket) Close() error {
-	pool.PutUdpBuf(c.buf)
+	pool.PutBuf(c.buf)
 	return c.PacketConn.Close()
 }
diff --git a/common/pool/pool.go b/common/pool/pool.go
index e9c2b81..7ca5430 100644
--- a/common/pool/pool.go
+++ b/common/pool/pool.go
@@ -2,7 +2,7 @@ package pool
 
 import "sync"
 
-const BufferSize = 4108
+const BufferSize = 4096
 
 var (
 	poolMap map[int]*sync.Pool
diff --git a/common/pool/udp_buffer_pool.go b/common/pool/udp_buffer_pool.go
deleted file mode 100644
index 2bb3de8..0000000
--- a/common/pool/udp_buffer_pool.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package pool
-
-import "sync"
-
-var udpPool *sync.Pool
-
-const MAX_UDP_BUF_SIZE int = 65507
-
-func init() {
-	udpPool = &sync.Pool{
-		New: func() interface{} {
-			return make([]byte, MAX_UDP_BUF_SIZE)
-		},
-	}
-}
-
-func GetUdpBuf() []byte {
-	buf := udpPool.Get().([]byte)
-	buf = buf[:cap(buf)]
-	return buf
-}
-
-func PutUdpBuf(buf []byte) {
-	udpPool.Put(buf)
-}
diff --git a/proxy/server/shadowsocks.go b/proxy/server/shadowsocks.go
index 8fcfe58..ec0c1a1 100644
--- a/proxy/server/shadowsocks.go
+++ b/proxy/server/shadowsocks.go
@@ -25,12 +25,6 @@ import (
 
 type mode int
 
-const (
-	remoteServer mode = iota
-	relayClient
-	socksClient
-)
-
 var (
 	logging *log.Logging
 	// ShadowsocksServerList Global map for store shadowsocks proxy
@@ -268,8 +262,18 @@ func relayTCP(left, right net.Conn) (int64, int64, error) {
 		Err error
 	}
 	ch := make(chan res)
+	defer func() {
+		if e := recover(); e != nil {
+			log.Error("panic in timedCopy: %v", e)
+		}
+	}()
 
 	go func() {
+		defer func() {
+			if e := recover(); e != nil {
+				log.Error("panic in timedCopy: %v", e)
+			}
+		}()
 		n, err := io.Copy(right, left)
 		right.SetDeadline(time.Now()) // wake up the other goroutine blocking on right
 		left.SetDeadline(time.Now())  // wake up the other goroutine blocking on left
@@ -332,8 +336,8 @@ func (s *ShadowsocksProxy) startUDP() error {
 	}
 
 	nm := newNATmap(s.ConnectTimeout)
-	buf := pool.GetUdpBuf()
-	defer pool.PutUdpBuf(buf)
+	buf := pool.GetBuf()
+	defer pool.PutBuf(buf)
 
 	// logging.Info("listening UDP on %s", addr)
 
@@ -384,7 +388,7 @@ func (s *ShadowsocksProxy) startUDP() error {
 					continue
 				}
 
-				nm.Add(raddr, server, pc, remoteServer)
+				nm.Add(raddr, server, pc)
 			}
 
 			_, err = pc.WriteTo(payload, tgtUDPAddr) // accept only UDPAddr despite the signature
@@ -457,7 +461,6 @@ func (m *natmap) Get(key string) net.PacketConn {
 func (m *natmap) Set(key string, pc net.PacketConn) {
 	m.Lock()
 	defer m.Unlock()
-
 	m.m[key] = pc
 }
 
@@ -473,11 +476,10 @@ func (m *natmap) Del(key string) net.PacketConn {
 	return nil
 }
 
-func (m *natmap) Add(peer net.Addr, dst, src net.PacketConn, role mode) {
+func (m *natmap) Add(peer net.Addr, dst, src net.PacketConn) {
 	m.Set(peer.String(), src)
-
 	go func() {
-		timedCopy(dst, peer, src, m.timeout, role)
+		timedCopy(dst, peer, src, m.timeout)
 		if pc := m.Del(peer.String()); pc != nil {
 			pc.Close()
 		}
@@ -485,9 +487,14 @@ func (m *natmap) Add(peer net.Addr, dst, src net.PacketConn, role mode) {
 }
 
 // copy from src to dst at target with read timeout
-func timedCopy(dst net.PacketConn, target net.Addr, src net.PacketConn, timeout time.Duration, role mode) error {
-	buf := pool.GetUdpBuf()
-	defer pool.PutUdpBuf(buf)
+func timedCopy(dst net.PacketConn, target net.Addr, src net.PacketConn, timeout time.Duration) error {
+	buf := pool.GetBuf()
+	defer pool.PutBuf(buf)
+	defer func() {
+		if e := recover(); e != nil {
+			log.Error("panic in timedCopy: %v", e)
+		}
+	}()
 
 	for {
 		src.SetReadDeadline(time.Now().Add(timeout))
@@ -496,20 +503,11 @@ func timedCopy(dst net.PacketConn, target net.Addr, src net.PacketConn, timeout
 			return errors.Cause(err)
 		}
 
-		switch role {
-		case remoteServer: // server -> client: add original packet source
-			srcAddr := socks.ParseAddr(raddr.String())
-			srcAddrByte := srcAddr.Raw
-			copy(buf[len(srcAddrByte):], buf[:n])
-			copy(buf, srcAddrByte)
-			_, err = dst.WriteTo(buf[:len(srcAddrByte)+n], target)
-		case relayClient: // client -> user: strip original packet source
-			srcAddr := socks.SplitAddr(buf[:n])
-			srcAddrByte := srcAddr.Raw
-			_, err = dst.WriteTo(buf[len(srcAddrByte):n], target)
-		case socksClient: // client -> socks5 program: just set RSV and FRAG = 0
-			_, err = dst.WriteTo(append([]byte{0, 0, 0}, buf[:n]...), target)
-		}
+		srcAddr := socks.ParseAddr(raddr.String())
+		srcAddrByte := srcAddr.Raw
+		copy(buf[len(srcAddrByte):], buf[:n])
+		copy(buf, srcAddrByte)
+		_, err = dst.WriteTo(buf[:len(srcAddrByte)+n], target)
 
 		if err != nil {
 			return errors.Cause(err)