diff --git a/a-test.txt b/a-test.txt
new file mode 100644
index 000000000..2e65efe2a
--- /dev/null
+++ b/a-test.txt
@@ -0,0 +1 @@
+a
\ No newline at end of file
diff --git a/client/config.go b/client/config.go
index 3d807b60c..19f942d43 100644
--- a/client/config.go
+++ b/client/config.go
@@ -37,6 +37,8 @@ type Config struct {
 	SnmpPeriod   int    `json:"snmpperiod"`
 	Quiet        bool   `json:"quiet"`
 	TCP          bool   `json:"tcp"`
+	BindUDP      string `json:"bindudp"`
+	TCPBuf      int `json:"tcpbuf"`
 }
 
 func parseJSONConfig(config *Config, path string) error {
diff --git a/client/dial.go b/client/dial.go
index 4b892831f..2c1e2afc5 100644
--- a/client/dial.go
+++ b/client/dial.go
@@ -4,6 +4,7 @@ import (
 	"github.com/pkg/errors"
 	kcp "github.com/xtaci/kcp-go/v5"
 	"github.com/xtaci/tcpraw"
+	"net"
 )
 
 func dial(config *Config, block kcp.BlockCrypt) (*kcp.UDPSession, error) {
@@ -14,5 +15,25 @@ func dial(config *Config, block kcp.BlockCrypt) (*kcp.UDPSession, error) {
 		}
 		return kcp.NewConn(config.RemoteAddr, block, config.DataShard, config.ParityShard, conn)
 	}
+	if config.BindUDP != "" {
+		//log.Println("func dial() config.BindUDP = ", config.BindUDP)
+		return dialAndBindUdp(config, block)
+	}
 	return kcp.DialWithOptions(config.RemoteAddr, block, config.DataShard, config.ParityShard)
 }
+
+func dialAndBindUdp(config *Config, block kcp.BlockCrypt) (*kcp.UDPSession, error) {
+	udpaddr, err := net.ResolveUDPAddr("udp", config.BindUDP)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+	network := "udp4"
+	if udpaddr.IP.To4() == nil {
+		network = "udp"
+	}
+	conn, err := net.ListenUDP(network, udpaddr)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+	return kcp.NewConn(config.RemoteAddr, block, config.DataShard, config.ParityShard, conn)
+}
diff --git a/client/main.go b/client/main.go
index e6a792377..f9b20ff7e 100644
--- a/client/main.go
+++ b/client/main.go
@@ -238,6 +238,16 @@ func main() {
 			Value: "", // when the value is not empty, the config path must exists
 			Usage: "config from json file, which will override the command from shell",
 		},
+		cli.StringFlag{
+			Name:  "bindudp,b", //hedahong add
+			Value: "", // when the value is not empty, OS automatic route
+			Usage: "bind output network address for udp socket",
+		},
+		cli.IntFlag{
+			Name:  "tcpbuf", //hedahong add
+			Value: 0, // tcp socket buffer size in bytes( linux defaults 2MB) //212992
+			Usage: "per-socket buffer in bytes",
+		},
 	}
 	myApp.Action = func(c *cli.Context) error {
 		config := Config{}
@@ -271,6 +281,8 @@ func main() {
 		config.SnmpPeriod = c.Int("snmpperiod")
 		config.Quiet = c.Bool("quiet")
 		config.TCP = c.Bool("tcp")
+		config.BindUDP = c.String("bindudp") //hedahong add
+		config.TCPBuf = c.Int("tcpbuf")      //hedahong add
 
 		if c.String("c") != "" {
 			err := parseJSONConfig(&config, c.String("c"))
@@ -324,6 +336,8 @@ func main() {
 		log.Println("snmpperiod:", config.SnmpPeriod)
 		log.Println("quiet:", config.Quiet)
 		log.Println("tcp:", config.TCP)
+		log.Println("---bindudp:", config.BindUDP)
+		log.Println("---tcpbuf:", config.TCPBuf)
 
 		// parameters check
 		if config.SmuxVer > maxSmuxVer {
@@ -441,6 +455,17 @@ func main() {
 			if err != nil {
 				log.Fatalf("%+v", err)
 			}
+
+			//hedahong add
+			log.Println("new client:", p1.RemoteAddr(), "-->", p1.LocalAddr())
+			if config.TCPBuf > 0 {
+				p1.SetReadBuffer(config.TCPBuf);  // hedahong add
+				p1.SetWriteBuffer(config.TCPBuf); // hedahong add
+				//log.Println("config.TCPBuf === ",config.TCPBuf)
+			} else {
+				//log.Println("config.TCPBuf = 0 ,OS setting default")
+			}
+
 			idx := rr % numconn
 
 			// do auto expiration && reconnection
diff --git a/go.sum b/go.sum
index 0207d15cd..7586af691 100644
--- a/go.sum
+++ b/go.sum
@@ -25,7 +25,7 @@ github.com/templexxx/xorsimd v0.4.1 h1:iUZcywbOYDRAZUasAs2eSCUW8eobuZDy0I9FJiORk
 github.com/templexxx/xorsimd v0.4.1/go.mod h1:W+ffZz8jJMH2SXwuKu9WhygqBMbFnp14G2fqEr8qaNo=
 github.com/tjfoc/gmsm v1.0.1 h1:R11HlqhXkDospckjZEihx9SW/2VW0RgdwrykyWMFOQU=
 github.com/tjfoc/gmsm v1.0.1/go.mod h1:XxO4hdhhrzAd+G4CjDqaOkd0hUzmtPR/d3EiBBMn/wc=
-github.com/tjfoc/gmsm v1.3.0 h1:i7c6Za/IlgBvnGxYpfD7L3TGuaS+v6oGcgq+J9/ecEA=
+github.com/tjfoc/gmsm v1.3.0 h1:qhgkrZru95jFP9NbVPknJvc9vgkMXhOEzkOASKdc0oQ=
 github.com/tjfoc/gmsm v1.3.0/go.mod h1:HaUcFuY0auTiaHB9MHFGCPx5IaLhTUd2atbCFBQXn9w=
 github.com/urfave/cli v1.21.0 h1:wYSSj06510qPIzGSua9ZqsncMmWE3Zr55KBERygyrxE=
 github.com/urfave/cli v1.21.0/go.mod h1:lxDj6qX9Q6lWQxIrbrT0nwecwUtRnhVZAJjJZrVUZZQ=