diff --git a/transport/internet/kcp/connection.go b/transport/internet/kcp/connection.go
index 209a282af..6f2f77966 100644
--- a/transport/internet/kcp/connection.go
+++ b/transport/internet/kcp/connection.go
@@ -429,7 +429,7 @@ func (this *Connection) Input(data []byte) int {
 			this.dataOutputCond.Signal()
 		case *CmdOnlySegment:
 			this.HandleOption(seg.Opt)
-			if seg.Cmd == SegmentCommandTerminated {
+			if seg.Cmd == CommandTerminate {
 				state := this.State()
 				if state == StateActive ||
 					state == StatePeerClosed {
@@ -469,7 +469,7 @@ func (this *Connection) flush() {
 		defer seg.Release()
 
 		seg.Conv = this.conv
-		seg.Cmd = SegmentCommandTerminated
+		seg.Cmd = CommandTerminate
 		this.output.Write(seg)
 		this.output.Flush()
 
@@ -493,7 +493,7 @@ func (this *Connection) flush() {
 	if this.sendingWorker.PingNecessary() || this.receivingWorker.PingNecessary() || current-atomic.LoadUint32(&this.lastPingTime) >= 5000 {
 		seg := NewCmdOnlySegment()
 		seg.Conv = this.conv
-		seg.Cmd = SegmentCommandPing
+		seg.Cmd = CommandPing
 		seg.ReceivinNext = this.receivingWorker.nextNumber
 		seg.SendingNext = this.sendingWorker.firstUnacknowledged
 		if this.State() == StateReadyToClose {
diff --git a/transport/internet/kcp/listener.go b/transport/internet/kcp/listener.go
index c95cda534..1f82ca6fb 100644
--- a/transport/internet/kcp/listener.go
+++ b/transport/internet/kcp/listener.go
@@ -63,11 +63,11 @@ func (this *Listener) OnReceive(payload *alloc.Buffer, src v2net.Destination) {
 		return
 	}
 	conv := serial.BytesToUint16(payload.Value)
-	cmd := SegmentCommand(payload.Value[2])
+	cmd := Command(payload.Value[2])
 	sourceId := src.NetAddr() + "|" + serial.Uint16ToString(conv)
 	conn, found := this.sessions[sourceId]
 	if !found {
-		if cmd == SegmentCommandTerminated {
+		if cmd == CommandTerminate {
 			return
 		}
 		log.Debug("KCP|Listener: Creating session with id(", sourceId, ") from ", src)
diff --git a/transport/internet/kcp/segment.go b/transport/internet/kcp/segment.go
index c20c66877..1c8c739eb 100644
--- a/transport/internet/kcp/segment.go
+++ b/transport/internet/kcp/segment.go
@@ -7,13 +7,13 @@ import (
 	"github.com/v2ray/v2ray-core/common/serial"
 )
 
-type SegmentCommand byte
+type Command byte
 
 const (
-	SegmentCommandACK        SegmentCommand = 0
-	SegmentCommandData       SegmentCommand = 1
-	SegmentCommandTerminated SegmentCommand = 2
-	SegmentCommandPing       SegmentCommand = 3
+	CommandACK       Command = 0
+	CommandData      Command = 1
+	CommandTerminate Command = 2
+	CommandPing      Command = 3
 )
 
 type SegmentOption byte
@@ -51,7 +51,7 @@ func NewDataSegment() *DataSegment {
 
 func (this *DataSegment) Bytes(b []byte) []byte {
 	b = serial.Uint16ToBytes(this.Conv, b)
-	b = append(b, byte(SegmentCommandData), byte(this.Opt))
+	b = append(b, byte(CommandData), byte(this.Opt))
 	b = serial.Uint32ToBytes(this.Timestamp, b)
 	b = serial.Uint32ToBytes(this.Number, b)
 	b = serial.Uint32ToBytes(this.SendingNext, b)
@@ -99,7 +99,7 @@ func (this *AckSegment) ByteSize() int {
 
 func (this *AckSegment) Bytes(b []byte) []byte {
 	b = serial.Uint16ToBytes(this.Conv, b)
-	b = append(b, byte(SegmentCommandACK), byte(this.Opt))
+	b = append(b, byte(CommandACK), byte(this.Opt))
 	b = serial.Uint32ToBytes(this.ReceivingWindow, b)
 	b = serial.Uint32ToBytes(this.ReceivingNext, b)
 	b = append(b, this.Count)
@@ -117,7 +117,7 @@ func (this *AckSegment) Release() {
 
 type CmdOnlySegment struct {
 	Conv         uint16
-	Cmd          SegmentCommand
+	Cmd          Command
 	Opt          SegmentOption
 	SendingNext  uint32
 	ReceivinNext uint32
@@ -150,11 +150,11 @@ func ReadSegment(buf []byte) (Segment, []byte) {
 	conv := serial.BytesToUint16(buf)
 	buf = buf[2:]
 
-	cmd := SegmentCommand(buf[0])
+	cmd := Command(buf[0])
 	opt := SegmentOption(buf[1])
 	buf = buf[2:]
 
-	if cmd == SegmentCommandData {
+	if cmd == CommandData {
 		seg := NewDataSegment()
 		seg.Conv = conv
 		seg.Opt = opt
@@ -182,7 +182,7 @@ func ReadSegment(buf []byte) (Segment, []byte) {
 		return seg, buf
 	}
 
-	if cmd == SegmentCommandACK {
+	if cmd == CommandACK {
 		seg := NewAckSegment()
 		seg.Conv = conv
 		seg.Opt = opt