diff --git a/utils/ss/pipe.go b/utils/ss/pipe.go
deleted file mode 100644
index 5f4645b..0000000
--- a/utils/ss/pipe.go
+++ /dev/null
@@ -1,105 +0,0 @@
-package ss
-
-import (
-	"bytes"
-	"encoding/binary"
-	"io"
-	"log"
-	"net"
-	"time"
-)
-
-func SetReadTimeout(c net.Conn) {
-	c.SetReadDeadline(time.Now().Add(time.Second * 5))
-}
-
-// PipeThenClose copies data from src to dst, closes dst when done.
-func PipeThenClose(src, dst net.Conn, addFlow func(int)) {
-	defer dst.Close()
-	buf := leakyBuf.Get()
-	defer leakyBuf.Put(buf)
-	for {
-		SetReadTimeout(src)
-		n, err := src.Read(buf)
-		if addFlow != nil {
-			addFlow(n)
-		}
-		// read may return EOF with n > 0
-		// should always process n > 0 bytes before handling error
-		if n > 0 {
-			// Note: avoid overwrite err returned by Read.
-			if _, err := dst.Write(buf[0:n]); err != nil {
-				log.Println("write:", err)
-				break
-			}
-		}
-		if err != nil {
-			// Always "use of closed network connection", but no easy way to
-			// identify this specific error. So just leave the error along for now.
-			// More info here: https://code.google.com/p/go/issues/detail?id=4373
-			/*
-				if bool(log.) && err != io.EOF {
-					log.Println("read:", err)
-				}
-			*/
-			break
-		}
-	}
-	return
-}
-
-// PipeThenClose copies data from src to dst, closes dst when done, with ota verification.
-func PipeThenCloseOta(src *Conn, dst net.Conn, addFlow func(int)) {
-	const (
-		dataLenLen  = 2
-		hmacSha1Len = 10
-		idxData0    = dataLenLen + hmacSha1Len
-	)
-
-	defer func() {
-		dst.Close()
-	}()
-	// sometimes it have to fill large block
-	buf := leakyBuf.Get()
-	defer leakyBuf.Put(buf)
-	for i := 1; ; i += 1 {
-		SetReadTimeout(src)
-		if n, err := io.ReadFull(src, buf[:dataLenLen+hmacSha1Len]); err != nil {
-			if err == io.EOF {
-				break
-			}
-			log.Printf("conn=%p #%v read header error n=%v: %v", src, i, n, err)
-			break
-		}
-		dataLen := binary.BigEndian.Uint16(buf[:dataLenLen])
-		expectedHmacSha1 := buf[dataLenLen:idxData0]
-
-		var dataBuf []byte
-		if len(buf) < int(idxData0+dataLen) {
-			dataBuf = make([]byte, dataLen)
-		} else {
-			dataBuf = buf[idxData0 : idxData0+dataLen]
-		}
-		if n, err := io.ReadFull(src, dataBuf); err != nil {
-			if err == io.EOF {
-				break
-			}
-			log.Printf("conn=%p #%v read data error n=%v: %v", src, i, n, err)
-			break
-		}
-		addFlow(int(dataLen))
-		chunkIdBytes := make([]byte, 4)
-		chunkId := src.GetAndIncrChunkId()
-		binary.BigEndian.PutUint32(chunkIdBytes, chunkId)
-		actualHmacSha1 := HmacSha1(append(src.GetIv(), chunkIdBytes...), dataBuf)
-		if !bytes.Equal(expectedHmacSha1, actualHmacSha1) {
-			log.Printf("conn=%p #%v read data hmac-sha1 mismatch, iv=%v chunkId=%v src=%v dst=%v len=%v expeced=%v actual=%v", src, i, src.GetIv(), chunkId, src.RemoteAddr(), dst.RemoteAddr(), dataLen, expectedHmacSha1, actualHmacSha1)
-			break
-		}
-		if n, err := dst.Write(dataBuf); err != nil {
-			log.Printf("conn=%p #%v write data error n=%v: %v", dst, i, n, err)
-			break
-		}
-	}
-	return
-}