diff --git a/utils/ss/conn.go b/utils/ss/conn.go
index 83f0681..9d2ddc4 100644
--- a/utils/ss/conn.go
+++ b/utils/ss/conn.go
@@ -71,17 +71,7 @@ func DialWithRawAddr(rawConn *net.Conn, rawaddr []byte, server string, cipher *C
 	} else {
 		c = NewConn(conn, cipher)
 	}
-	if cipher.ota {
-		if c.enc == nil {
-			if _, err = c.initEncrypt(); err != nil {
-				return
-			}
-		}
-		// since we have initEncrypt, we must send iv manually
-		conn.Write(cipher.iv)
-		rawaddr[0] |= OneTimeAuthMask
-		rawaddr = otaConnectAuth(cipher.iv, cipher.key, rawaddr)
-	}
+
 	if _, err = c.write(rawaddr); err != nil {
 		c.Close()
 		return nil, err
@@ -150,10 +140,7 @@ func (c *Conn) Read(b []byte) (n int, err error) {
 
 func (c *Conn) Write(b []byte) (n int, err error) {
 	nn := len(b)
-	if c.ota {
-		chunkId := c.GetAndIncrChunkId()
-		b = otaReqChunkAuth(c.iv, chunkId, b)
-	}
+
 	headerLen := len(b) - nn
 
 	n, err = c.write(b)
diff --git a/utils/ss/util.go b/utils/ss/util.go
index dcc56db..45a3787 100644
--- a/utils/ss/util.go
+++ b/utils/ss/util.go
@@ -1,15 +1,7 @@
 package ss
 
 import (
-	"crypto/hmac"
-	"crypto/sha1"
-	"encoding/binary"
-	"errors"
-	"fmt"
-	"io"
 	"net"
-	"os"
-	"strconv"
 
 	"github.com/snail007/goproxy/utils"
 )
@@ -19,39 +11,6 @@ const maxNBuf = 2048
 
 var leakyBuf = utils.NewLeakyBuf(maxNBuf, leakyBufSize)
 
-func IsFileExists(path string) (bool, error) {
-	stat, err := os.Stat(path)
-	if err == nil {
-		if stat.Mode()&os.ModeType == 0 {
-			return true, nil
-		}
-		return false, errors.New(path + " exists but is not regular file")
-	}
-	if os.IsNotExist(err) {
-		return false, nil
-	}
-	return false, err
-}
-
-func HmacSha1(key []byte, data []byte) []byte {
-	hmacSha1 := hmac.New(sha1.New, key)
-	hmacSha1.Write(data)
-	return hmacSha1.Sum(nil)[:10]
-}
-
-func otaConnectAuth(iv, key, data []byte) []byte {
-	return append(data, HmacSha1(append(iv, key...), data)...)
-}
-
-func otaReqChunkAuth(iv []byte, chunkId uint32, data []byte) []byte {
-	nb := make([]byte, 2)
-	binary.BigEndian.PutUint16(nb, uint16(len(data)))
-	chunkIdBytes := make([]byte, 4)
-	binary.BigEndian.PutUint32(chunkIdBytes, chunkId)
-	header := append(nb, HmacSha1(append(iv, chunkIdBytes...), data)...)
-	return append(header, data...)
-}
-
 const (
 	idType  = 0 // address type index
 	idIP0   = 1 // ip addres start index
@@ -67,65 +26,3 @@ const (
 	lenDmBase   = 2               // 1addrLen + 2port, plus addrLen
 	lenHmacSha1 = 10
 )
-
-func GetRequest(conn *Conn) (host string, err error) {
-
-	// buf size should at least have the same size with the largest possible
-	// request size (when addrType is 3, domain name has at most 256 bytes)
-	// 1(addrType) + 1(lenByte) + 255(max length address) + 2(port) + 10(hmac-sha1)
-	buf := make([]byte, 269)
-	// read till we get possible domain length field
-	if _, err = io.ReadFull(conn, buf[:idType+1]); err != nil {
-		return
-	}
-
-	var reqStart, reqEnd int
-	addrType := buf[idType]
-	switch addrType & AddrMask {
-	case typeIPv4:
-		reqStart, reqEnd = idIP0, idIP0+lenIPv4
-	case typeIPv6:
-		reqStart, reqEnd = idIP0, idIP0+lenIPv6
-	case typeDm:
-		if _, err = io.ReadFull(conn, buf[idType+1:idDmLen+1]); err != nil {
-			return
-		}
-		reqStart, reqEnd = idDm0, idDm0+int(buf[idDmLen])+lenDmBase
-	default:
-		err = fmt.Errorf("addr type %d not supported", addrType&AddrMask)
-		return
-	}
-
-	if _, err = io.ReadFull(conn, buf[reqStart:reqEnd]); err != nil {
-		return
-	}
-
-	// Return string for typeIP is not most efficient, but browsers (Chrome,
-	// Safari, Firefox) all seems using typeDm exclusively. So this is not a
-	// big problem.
-	switch addrType & AddrMask {
-	case typeIPv4:
-		host = net.IP(buf[idIP0 : idIP0+net.IPv4len]).String()
-	case typeIPv6:
-		host = net.IP(buf[idIP0 : idIP0+net.IPv6len]).String()
-	case typeDm:
-		host = string(buf[idDm0 : idDm0+int(buf[idDmLen])])
-	}
-	// parse port
-	port := binary.BigEndian.Uint16(buf[reqEnd-2 : reqEnd])
-	host = net.JoinHostPort(host, strconv.Itoa(int(port)))
-
-	return
-}
-
-type ClosedFlag struct {
-	flag bool
-}
-
-func (flag *ClosedFlag) SetClosed() {
-	flag.flag = true
-}
-
-func (flag *ClosedFlag) IsClosed() bool {
-	return flag.flag
-}