diff --git a/configure b/configure
index 0b6294ab..b784d016 100755
--- a/configure
+++ b/configure
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for shadowsocks-libev 2.3.0.
+# Generated by GNU Autoconf 2.69 for shadowsocks-libev 2.3.1.
 #
 # Report bugs to <max.c.lv@gmail.com>.
 #
@@ -590,8 +590,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='shadowsocks-libev'
 PACKAGE_TARNAME='shadowsocks-libev'
-PACKAGE_VERSION='2.3.0'
-PACKAGE_STRING='shadowsocks-libev 2.3.0'
+PACKAGE_VERSION='2.3.1'
+PACKAGE_STRING='shadowsocks-libev 2.3.1'
 PACKAGE_BUGREPORT='max.c.lv@gmail.com'
 PACKAGE_URL=''
 
@@ -1339,7 +1339,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures shadowsocks-libev 2.3.0 to adapt to many kinds of systems.
+\`configure' configures shadowsocks-libev 2.3.1 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1410,7 +1410,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of shadowsocks-libev 2.3.0:";;
+     short | recursive ) echo "Configuration of shadowsocks-libev 2.3.1:";;
    esac
   cat <<\_ACEOF
 
@@ -1536,7 +1536,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-shadowsocks-libev configure 2.3.0
+shadowsocks-libev configure 2.3.1
 generated by GNU Autoconf 2.69
 
 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -2059,7 +2059,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by shadowsocks-libev $as_me 2.3.0, which was
+It was created by shadowsocks-libev $as_me 2.3.1, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   $ $0 $@
@@ -2880,7 +2880,7 @@ fi
 
 # Define the identity of the package.
  PACKAGE='shadowsocks-libev'
- VERSION='2.3.0'
+ VERSION='2.3.1'
 
 
 cat >>confdefs.h <<_ACEOF
@@ -15894,7 +15894,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by shadowsocks-libev $as_me 2.3.0, which was
+This file was extended by shadowsocks-libev $as_me 2.3.1, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -15960,7 +15960,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-shadowsocks-libev config.status 2.3.0
+shadowsocks-libev config.status 2.3.1
 configured by $0, generated by GNU Autoconf 2.69,
   with options \\"\$ac_cs_config\\"
 
diff --git a/configure.ac b/configure.ac
index 702ee259..17860729 100755
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@ dnl                                               -*- Autoconf -*-
 dnl Process this file with autoconf to produce a configure script.
 
 AC_PREREQ([2.67])
-AC_INIT([shadowsocks-libev], [2.3.0], [max.c.lv@gmail.com])
+AC_INIT([shadowsocks-libev], [2.3.1], [max.c.lv@gmail.com])
 AC_CONFIG_SRCDIR([src/encrypt.c])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_AUX_DIR(auto)
diff --git a/debian/changelog b/debian/changelog
index aae740cd..6ba33fe0 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,10 @@
+shadowsocks-libev (2.3.1-1) unstable; urgency=low
+
+  * Fix an issue of connection cache of UDP relay.
+  * Add support of onetime authentication for header verification.
+
+ -- Max Lv <max.c.lv@gmail.com>  Fri, 04 Sep 2015 07:54:02 +0900
+
 shadowsocks-libev (2.3.0-1) unstable; urgency=low
 
   * Add manager mode to support multi-user and traffic stat.
diff --git a/openwrt/Makefile b/openwrt/Makefile
index 3160f97a..d5761490 100644
--- a/openwrt/Makefile
+++ b/openwrt/Makefile
@@ -1,7 +1,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=shadowsocks-libev
-PKG_VERSION:=2.3.0
+PKG_VERSION:=2.3.1
 PKG_RELEASE=$(PKG_SOURCE_VERSION)
 
 PKG_SOURCE_URL:=https://github.com/shadowsocks/shadowsocks-libev/archive
diff --git a/src/server.c b/src/server.c
index dd298ab0..900bf655 100644
--- a/src/server.c
+++ b/src/server.c
@@ -519,13 +519,13 @@ static void server_recv_cb(EV_P_ ev_io *w, int revents)
     } else if (server->stage == 0) {
 
         /*
-         * Shadowsocks Protocol:
+         * Shadowsocks TCP Relay Protocol:
          *
-         *    +------+----------+----------+
-         *    | ATYP | DST.ADDR | DST.PORT |
-         *    +------+----------+----------+
-         *    |  1   | Variable |    2     |
-         *    +------+----------+----------+
+         *    +------+----------+----------+------+
+         *    | ATYP | DST.ADDR | DST.PORT | AUTH |
+         *    +------+----------+----------+------+
+         *    |  1   | Variable |    2     |  16  |
+         *    +------+----------+----------+------+
          */
 
         int offset = 0;