add snmp reset

This reverts commit 2f479b788c.

.github/ISSUE_TEMPLATE

@@ -2,11 +2,12 @@ Before firing issue, make sure you figured out the following common questions.
 
 PLEASE DO SEARCH FIRST.
 
-1. Are you using the **latest release**?
-2. Which **OS** do you use?
-3. Which end for this issue related to, **client or server**?
-4. Are you using the **same version** for both client & server
-5. Did you correctly set the ***-target value, -t value	target server address (default: "127.0.0.1:12948")*** on the server side?
-6. Can ```telnet target port``` successful?
-7. ```-nocomp, -datashard, -parityshard,  -key, -crypt``` ***must be the same*** on both side.
-8. Does your ***firewall allows UDP*** communications? (including your ISP Cable-Modem)
+1. Check your ```-key xxx``` for at least 3 times, ***MAKE SURE*** both sides share the same secret.
+2. ```-nocomp, -datashard, -parityshard,  -key, -crypt``` ***must be the same*** on both side.
+3. Did you correctly set the ***-target*** on the server side?
+4. ***MAKE SURE*** ```telnet target port``` on your server successful(don't ask me why couldn't).
+5. Does your ***firewall allows UDP*** communications? (including your ISP Cable-Modem)
+6. Are you using the **same version** for both client & server
+7. Are you using the **latest release**?
+8. Which **OS** do you use?
+9. Which end for this issue related to, **client or server**?

Dockerfile

@@ -3,7 +3,6 @@ MAINTAINER xtaci <daniel820313@gmail.com>
 RUN apk update && \
     apk upgrade && \
     apk add git
-RUN go get github.com/xtaci/kcptun/client
-RUN go get github.com/xtaci/kcptun/server
+RUN go get github.com/xtaci/kcptun/client && go get github.com/xtaci/kcptun/server
 EXPOSE 29900/udp
 EXPOSE 12948

README.en.md

@@ -1,7 +1,7 @@
 # <img src="logo.png" alt="kcptun" height="60px" /> 
-[![GoDoc][1]][2] [![Release][13]][14] [![Powered][17]][18] [![MIT licensed][11]][12] [![Build Status][3]][4] [![Go Report Card][5]][6] [![Downloads][15]][16] [![Gitter][19]][20]
-[1]: https://godoc.org/github.com/xtaci/kcptun?status.svg
-[2]: https://godoc.org/github.com/xtaci/kcptun
+[![Release][13]][14] [![Powered][17]][18] [![MIT licensed][11]][12] [![Build Status][3]][4] [![Go Report Card][5]][6] [![Downloads][15]][16] [![Gitter][19]][20] [![Docker][1]][2]
+[1]: https://images.microbadger.com/badges/image/xtaci/kcptun.svg
+[2]: https://microbadger.com/images/xtaci/kcptun
 [3]: https://travis-ci.org/xtaci/kcptun.svg?branch=master
 [4]: https://travis-ci.org/xtaci/kcptun
 [5]: https://goreportcard.com/badge/github.com/xtaci/kcptun
@@ -28,10 +28,13 @@ A tool for converting tcp stream into kcp+udp stream, :zap: ***[download address
 ***kcptun is based on [kcp-go](https://github.com/xtaci/kcp-go)***   
 
 ### *QuickStart* :lollipop:
+Client, server, respectively, download the corresponding platform binary compression package, and extract, through the following command to start port forwarding.
 ```
-Server Side: ./server_linux_amd64 -t "127.0.0.1:1080" -l ":4000" -mode fast2  // forwarding to local port 1080
-Client Side: ./client_darwin_amd64 -r "SERVERIP:4000" -l ":1080" -mode fast2  // listening on port 1080
+Server: ./server_linux_amd64 -t "SERVER_IP:8388" -l ":4000" -mode fast2
+Client: ./client_darwin_amd64 -r "SERVER_IP:4000" -l ":8388" -mode fast2
 ```
+The above command can establish 8388/tcp port forwarding (through 4000/udp port).
+
 
 ### *Performance* :lollipop:
 <img src="fast.png" alt="fast.com" height="256px" />       
@@ -40,16 +43,17 @@ Client Side: ./client_darwin_amd64 -r "SERVERIP:4000" -l ":1080" -mode fast2  //
 * WIFI: 5GHz TL-WDR3320
 
 ### *Usage* :lollipop:
+Help output under MacOS X:
 ```
 $ ./client_darwin_amd64 -h
 NAME:
-   kcptun - kcptun client
+   kcptun - client(with SMUX)
 
 USAGE:
    client_darwin_amd64 [global options] command [command options] [arguments...]
 
 VERSION:
-   20160811
+   20160922
 
 COMMANDS:
      help, h  Shows a list of commands or help for one command
@@ -57,31 +61,32 @@ COMMANDS:
 GLOBAL OPTIONS:
    --localaddr value, -l value   local listen address (default: ":12948")
    --remoteaddr value, -r value  kcp server address (default: "vps:29900")
-   --key value                   key for communcation, must be the same as kcptun server (default: "it's a secrect") [$KCPTUN_KEY]
-   --crypt value                 methods for encryption: aes, tea, xor, none (default: "aes")
-   --mode value                  mode for communication: fast3, fast2, fast, normal (default: "fast")
-   --conn value                  establish N physical connections as specified by 'conn' to server (default: 1)
-   --mtu value                   set MTU of UDP packets, suggest 'tracepath' to discover path mtu (default: 1350)
+   --key value                   pre-shared secret between client and server (default: "it's a secrect") [$KCPTUN_KEY]
+   --crypt value                 aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, none (default: "aes")
+   --mode value                  profiles: fast3, fast2, fast, normal (default: "fast")
+   --conn value                  set num of UDP connections to server (default: 1)
+   --autoexpire value            set auto expiration time(in seconds) for a single UDP connection, 0 to disable (default: 0)
+   --mtu value                   set maximum transmission unit for UDP packets (default: 1350)
    --sndwnd value                set send window size(num of packets) (default: 128)
    --rcvwnd value                set receive window size(num of packets) (default: 1024)
-   --nocomp                      disable compression
    --datashard value             set reed-solomon erasure coding - datashard (default: 10)
    --parityshard value           set reed-solomon erasure coding - parityshard (default: 3)
    --dscp value                  set DSCP(6bit) (default: 0)
+   --nocomp                      disable compression
+   --log value                   specify a log file to output, default goes to stderr
+   -c value                      config from json file, which will override the command from shell
    --help, -h                    show help
    --version, -v                 print the version
-```
 
-```
 $ ./server_darwin_amd64 -h
 NAME:
-   kcptun - kcptun server
+   kcptun - server(with SMUX)
 
 USAGE:
    server_darwin_amd64 [global options] command [command options] [arguments...]
 
 VERSION:
-   20160811
+   20160922
 
 COMMANDS:
      help, h  Shows a list of commands or help for one command
@@ -89,19 +94,24 @@ COMMANDS:
 GLOBAL OPTIONS:
    --listen value, -l value  kcp server listen address (default: ":29900")
    --target value, -t value  target server address (default: "127.0.0.1:12948")
-   --key value               key for communcation, must be the same as kcptun client (default: "it's a secrect") [$KCPTUN_KEY]
-   --crypt value             methods for encryption: aes, tea, xor, none (default: "aes")
-   --mode value              mode for communication: fast3, fast2, fast, normal (default: "fast")
-   --mtu value               set MTU of UDP packets, suggest 'tracepath' to discover path mtu (default: 1350)
+   --key value               pre-shared secret between client and server (default: "it's a secrect") [$KCPTUN_KEY]
+   --crypt value             aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, none (default: "aes")
+   --mode value              profiles: fast3, fast2, fast, normal (default: "fast")
+   --mtu value               set maximum transmission unit for UDP packets (default: 1350)
    --sndwnd value            set send window size(num of packets) (default: 1024)
    --rcvwnd value            set receive window size(num of packets) (default: 1024)
-   --nocomp                  disable compression
    --datashard value         set reed-solomon erasure coding - datashard (default: 10)
    --parityshard value       set reed-solomon erasure coding - parityshard (default: 3)
    --dscp value              set DSCP(6bit) (default: 0)
+   --nocomp                  disable compression
+   --log value               specify a log file to output, default goes to stderr
+   -c value                  config from json file, which will override the command from shell
    --help, -h                show help
    --version, -v             print the version
 ```
+#### *Parameters by Layers* :lollipop:   
+
+<p align="left"><img src="layeredparams.png" alt="params" height="450px"/></p>
 
 ### *Applications* :lollipop:   
 1. Real-time gaming.
@@ -124,6 +134,12 @@ other parameters can be set independently.
 
 ***NOTICE: if too much retranmission happens, it's quite possible the windows are too large***
 
+### *Security* :lollipop: 
+No matter what encryption you are using for application layer, if you specify ```-crypt none``` to kcptun, 
+the header will be ***PLAINTEXT*** to everyone; I suggest ```-crypt aes-128``` for encryption at least .
+
+NOTICE: ```-crypt xor``` is also insecure, do not use this unless you know what you are doing.
+
 ### *Memory Control* :lollipop: 
 Routers, mobile devices are sensitive to memory consumption; by setting GOGC environment(eg: GOGC=20) will lower memory consumption.
 Reference: https://blog.golang.org/go15gc
@@ -159,6 +175,7 @@ Manual control is supported with hidden parameters, you must understand KCP prot
 ```
  -mode manual -nodelay 1 -resend 2 -nc 1 -interval 20
 ```
+I suggest fast2 for high-loss network, normal for low-loss network.
 
 ### *Forward Error Correction* :lollipop: 
 In coding theory, the Reed–Solomon code belongs to the class of non-binary cyclic error-correcting codes. The Reed–Solomon code is based on univariate polynomials over finite fields.
@@ -167,7 +184,7 @@ It is able to detect and correct multiple symbol errors. By adding t check symbo
 
 ![reed-solomon](rs.png)
 
-Setting parameters of RS-Code with ```-datashard 10 -parityshard 3``` 
+Setting parameters of RS-Code with ```-datashard m -parityshard n```
 
 ### *Snappy Stream Compression* :lollipop: 
 > Snappy is a compression/decompression library. It does not aim for maximum
@@ -215,7 +232,7 @@ Of which ```RetransSegs,FastRetransSegs,LostSegs,OutSegs``` is the most useful.
 ### *Donations* :dollar:
 ![donate](donate.png)          
 
-All donations to this project will be used on the R&D of [gonet/2](http://gonet2.github.io/).
+Best wishes to you all.
 
 ### *References* :paperclip:
 1. https://github.com/skywind3000/kcp -- KCP - A Fast and Reliable ARQ Protocol.

README.md

@@ -1,7 +1,11 @@
-# <img src="logo.png" alt="kcptun" height="60px" /> 
-[![GoDoc][1]][2] [![Release][13]][14] [![Powered][17]][18] [![MIT licensed][11]][12] [![Build Status][3]][4] [![Go Report Card][5]][6] [![Downloads][15]][16] [![Gitter][19]][20]
-[1]: https://godoc.org/github.com/xtaci/kcptun?status.svg
-[2]: https://godoc.org/github.com/xtaci/kcptun
+<p align="center"><img src="logo.png" alt="kcptun" height="60px" /></p>
+<p align="center"><em>A Simple UDP Tunnel Based On KCP</em></p>
+
+-
+
+[![Release][13]][14] [![Powered][17]][18] [![MIT licensed][11]][12] [![Build Status][3]][4] [![Go Report Card][5]][6] [![Downloads][15]][16] [![Gitter][19]][20] [![Docker][1]][2]
+[1]: https://images.microbadger.com/badges/image/xtaci/kcptun.svg
+[2]: https://microbadger.com/images/xtaci/kcptun
 [3]: https://travis-ci.org/xtaci/kcptun.svg?branch=master
 [4]: https://travis-ci.org/xtaci/kcptun
 [5]: https://goreportcard.com/badge/github.com/xtaci/kcptun
@@ -19,35 +23,42 @@
 [19]: https://badges.gitter.im/xtaci/kcptun.svg
 [20]: https://gitter.im/xtaci/kcptun?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge
 
-***[kcp-go](https://github.com/xtaci/kcp-go)协议测试小工具 :zap: [官方下载地址](https://github.com/xtaci/kcptun/releases/latest):zap:***
+<p align="center"><img src="kcptun.png" alt="kcptun" height="200px"/></p>
+<p align="center"><a href="https://github.com/xtaci/kcptun/releases/latest">立即安装</a></p>
+<p align="center"><em>支持macOS/Linux/Windows/FreeBSD/ARM/Raspberry Pi/OpenWrt</em></p>
+<p align="right"><a href="https://github.com/xtaci/kcptun/blob/master/README.en.md">ENG</a></p>
 
-![kcptun](kcptun.png)
-[English Readme](README.en.md)
-### *快速设定* :lollipop:
+-
+
+### 快速设定
+
+客户端、服务器分别**下载**对应平台的二进制压缩包，并**解压**，通过下面的命令**启动**端口转发。
 ```
-服务器: ./server_linux_amd64 -t "127.0.0.1:8388" -l ":4000" -mode fast2  // 转发到服务器的本地8388端口
-客户端: ./client_darwin_amd64 -r "服务器IP地址:4000" -l ":8388" -mode fast2    // 监听客户端的本地8388端口
-注: 服务器端需要有服务监听8388端口
+服务器: ./server_linux_amd64 -t "服务器IP地址:8388" -l ":4000" -mode fast2
+客户端: ./client_darwin_amd64 -r "服务器IP地址:4000" -l ":8388" -mode fast2
 ```
+以上命令可以实现8388/tcp端口的转发（通过4000/udp端口）。
+
+### 速度对比
 
-### *速度对比* :lollipop:
 <img src="fast.png" alt="fast.com" height="256px" />       
 * 测速网站: https://fast.com
-* 接入: 100M ADSL
+* 接入速度: 100Mbps
 * WIFI: 5GHz TL-WDR3320
 
-### *使用方法* :lollipop:
-在Mac OS X El Capitan下的帮助输出: 
+### 使用方法
+
+在Mac OS X El Capitan下的帮助输出，注意默认值: 
 ```
 $ ./client_darwin_amd64 -h
 NAME:
-   kcptun - kcptun client
+   kcptun - client(with SMUX)
 
 USAGE:
    client_darwin_amd64 [global options] command [command options] [arguments...]
 
 VERSION:
-   20160811
+   20161025
 
 COMMANDS:
      help, h  Shows a list of commands or help for one command
@@ -55,31 +66,32 @@ COMMANDS:
 GLOBAL OPTIONS:
    --localaddr value, -l value   local listen address (default: ":12948")
    --remoteaddr value, -r value  kcp server address (default: "vps:29900")
-   --key value                   key for communcation, must be the same as kcptun server (default: "it's a secrect") [$KCPTUN_KEY]
-   --crypt value                 methods for encryption: aes, tea, xor, none (default: "aes")
-   --mode value                  mode for communication: fast3, fast2, fast, normal (default: "fast")
-   --conn value                  establish N physical connections as specified by 'conn' to server (default: 1)
-   --mtu value                   set MTU of UDP packets, suggest 'tracepath' to discover path mtu (default: 1350)
+   --key value                   pre-shared secret between client and server (default: "it's a secrect") [$KCPTUN_KEY]
+   --crypt value                 aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, none (default: "aes")
+   --mode value                  profiles: fast3, fast2, fast, normal (default: "fast")
+   --conn value                  set num of UDP connections to server (default: 1)
+   --autoexpire value            set auto expiration time(in seconds) for a single UDP connection, 0 to disable (default: 0)
+   --mtu value                   set maximum transmission unit for UDP packets (default: 1350)
    --sndwnd value                set send window size(num of packets) (default: 128)
    --rcvwnd value                set receive window size(num of packets) (default: 1024)
-   --nocomp                      disable compression
    --datashard value             set reed-solomon erasure coding - datashard (default: 10)
    --parityshard value           set reed-solomon erasure coding - parityshard (default: 3)
    --dscp value                  set DSCP(6bit) (default: 0)
+   --nocomp                      disable compression
+   --log value                   specify a log file to output, default goes to stderr
+   -c value                      config from json file, which will override the command from shell
    --help, -h                    show help
    --version, -v                 print the version
-```
 
-```
 $ ./server_darwin_amd64 -h
 NAME:
-   kcptun - kcptun server
+   kcptun - server(with SMUX)
 
 USAGE:
    server_darwin_amd64 [global options] command [command options] [arguments...]
 
 VERSION:
-   20160811
+   20161025
 
 COMMANDS:
      help, h  Shows a list of commands or help for one command
@@ -87,67 +99,131 @@ COMMANDS:
 GLOBAL OPTIONS:
    --listen value, -l value  kcp server listen address (default: ":29900")
    --target value, -t value  target server address (default: "127.0.0.1:12948")
-   --key value               key for communcation, must be the same as kcptun client (default: "it's a secrect") [$KCPTUN_KEY]
-   --crypt value             methods for encryption: aes, tea, xor, none (default: "aes")
-   --mode value              mode for communication: fast3, fast2, fast, normal (default: "fast")
-   --mtu value               set MTU of UDP packets, suggest 'tracepath' to discover path mtu (default: 1350)
+   --key value               pre-shared secret between client and server (default: "it's a secrect") [$KCPTUN_KEY]
+   --crypt value             aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, none (default: "aes")
+   --mode value              profiles: fast3, fast2, fast, normal (default: "fast")
+   --mtu value               set maximum transmission unit for UDP packets (default: 1350)
    --sndwnd value            set send window size(num of packets) (default: 1024)
    --rcvwnd value            set receive window size(num of packets) (default: 1024)
-   --nocomp                  disable compression
    --datashard value         set reed-solomon erasure coding - datashard (default: 10)
    --parityshard value       set reed-solomon erasure coding - parityshard (default: 3)
    --dscp value              set DSCP(6bit) (default: 0)
+   --nocomp                  disable compression
+   --log value               specify a log file to output, default goes to stderr
+   -c value                  config from json file, which will override the command from shell
    --help, -h                show help
    --version, -v             print the version
 ```
+#### 分层参数图
 
-### *参数调整* :lollipop: 
-***两端参数必须一致的有:***
-* datashard
-* parityshard
-* nocomp
-* key
-* crypt
+<p align="left"><img src="layeredparams.png" alt="params" height="450px"/></p>
+
+### 内置模式
+
+响应速度:     
+*fast3 > fast2 >* **[fast]** *> normal > default*        
+有效载荷比:     
+*default > normal >* **[fast]** *> fast2 > fast3*       
+中间mode参数比较均衡，总之就是越快，包重传越激进。       
+更高级的 **手动档** 需要理解KCP协议，并通过 **隐藏参数** 调整，例如:
+```
+ -mode manual -nodelay 1 -resend 2 -nc 1 -interval 20
+```
+
+* 搭配1. fast + FEC(5,5)
+* 搭配2. fast2 + FEC(10,3)
+* 搭配3. fast2 + FEC(0,0)
+
+默认profile参考: https://github.com/xtaci/kcptun/blob/master/client/main.go#L248
+
+### 前向纠错
+
+前向纠错采用Reed Solomon纠删码, 它的基本原理如下： 给定n个数据块d1, d2,…, dn，n和一个正整数m， RS根据n个数据块生成m个校验块， c1, c2,…, cm。 对于任意的n和m， 从n个原始数据块和m 个校验块中任取n块就能解码出原始数据， 即RS最多**容忍m个数据块或者校验块同时丢失**。
+
+![reed-solomon](rs.png)
+
+通过参数```-datashard n -parityshard m``` 在两端同时设定。
+
+数据包发送顺序严格遵循: n个datashard紧接m个parityshard，重复。
+
+注意：为了发挥FEC最佳效果，设置 parityshard/(parity+datashard) > packet loss，比如5/(5+5) > 30%
+
+### 窗口调整
+
+**两端参数必须一致的有**:
+
+* datashard --前向纠错
+* parityshard --前向纠错
+* nocomp --压缩
+* key --密钥
+* crypt --加密算法
 
 其余为两边可独立设定的参数
 
-*简易自我调优方法*：
+**简易窗口自我调优方法**：
+
 > 第一步：同时在两端逐步增大client rcvwnd和server sndwnd;        
 > 第二步：尝试下载，观察如果带宽利用率（服务器＋客户端两端都要观察）接近物理带宽则停止，否则跳转到第一步。
 
-***注意：产生大量重传时，一定是窗口偏大了***
+**注意：产生大量重传时，一定是窗口偏大了**
+
+### 安全
+
+无论你上层如何加密，如果```-crypt none```，那么**协议头部**都是**明文**的，建议至少采用```-crypt aes-128```加密，并修改密码。
+
+密码可以通过`-key`指定，也可以通过环境变量`KCPTUN_KEY`指定。
+
+注意: ```-crypt xor``` 也是不安全的，除非你知道你在做什么。 
+
+附加密速度Benchmark：
 
-*带宽计算公式*：
 ```
-在不丢包的情况下，有最大-rcvwnd 个数据包在网络上正在向你传输，以平均数据包大小avgsize计算，在任意时刻，有：     
-
-		network_cap = rcvwnd*avgsize
-
-数据流向你，这个值再除以ping值(rtt)，等于最大带宽使用量。
-
-		max_bandwidth = network_cap/rtt = rcvwnd*avgsize/rtt
-		
-举例，设rcvwnd = 1024, avgsize = 1KB, rtt = 400ms，则：
-
-		max_bandwidth = 1024 * 1KB / 400ms = 2.5MB/s ~= 25Mbps
-		
-（注：以上计算不包括前向纠错的数据量）
-
-前向纠错是最大带宽量的一个固定比例增加：
-
-		max_bandwidth_fec = max_bandwidth*(datashard+parityshard)/datashard
-
-举例，设datashard = 10 , partiyshard = 3，则：
-
-		max_bandwidth_fec = max_bandwidth * (10 + 3) /10 = 1.3*max_bandwidth ＝ 1.3 * 25Mbps = 32.5Mbps
+BenchmarkAES128-4      	  200000	     11182 ns/op
+BenchmarkAES192-4      	  200000	     12699 ns/op
+BenchmarkAES256-4      	  100000	     13757 ns/op
+BenchmarkTEA-4         	   50000	     26441 ns/op
+BenchmarkSimpleXOR-4   	 3000000	       441 ns/op
+BenchmarkBlowfish-4    	   30000	     48036 ns/op
+BenchmarkNone-4        	20000000	       106 ns/op
+BenchmarkCast5-4       	   20000	     60222 ns/op
+BenchmarkTripleDES-4   	    2000	    878759 ns/op
+BenchmarkTwofish-4     	   20000	     68501 ns/op
+BenchmarkXTEA-4        	   20000	     77417 ns/op
+BenchmarkSalsa20-4     	  300000	      4998 ns/op
 ```
 
-### *内存控制* :lollipop: 
-路由器，手机等嵌入式设备通常对内存用量敏感，通过调节环境变量GOGC（例如GOGC=20)后启动client，可以降低内存使用。      
+### 内存控制
+
+路由器，手机等嵌入式设备通常对**内存用量敏感**，通过调节环境变量GOGC（例如GOGC=20)后启动client，可以降低内存使用。      
 参考：https://blog.golang.org/go15gc
 
-### *流量控制* :lollipop: 
-***必要性: 针对流量敏感的服务器，做双保险。***      
+
+### DSCP
+
+DSCP差分服务代码点（Differentiated Services Code Point），IETF于1998年12月发布了Diff-Serv（Differentiated Service）的QoS分类标准。它在每个数据包IP头部的服务类别TOS标识字节中，利用已使用的**6比特**和未使用的2比特，通过编码值来区分优先级。     
+常用DSCP值可以参考[Wikipedia DSCP](https://en.wikipedia.org/wiki/Differentiated_services#Commonly_used_DSCP_values)，至于有没有用，完全取决于数据包经过的设备。 
+
+通过 ```-dscp ``` 参数指定dscp值，两端可分别设定。
+
+注意：设置dscp不一定会更好，需要尝试。
+
+### Snappy数据流压缩
+
+> Snappy is a compression/decompression library. It does not aim for maximum
+> compression, or compatibility with any other compression library; instead,
+> it aims for very high speeds and reasonable compression. For instance,
+> compared to the fastest mode of zlib, Snappy is an order of magnitude faster
+> for most inputs, but the resulting compressed files are anywhere from 20% to
+> 100% bigger.
+
+> Reference: http://google.github.io/snappy/
+
+通过参数 ```-nocomp``` 在两端同时设定以关闭压缩。
+> 提示: 关闭压缩可能会降低延迟。
+
+### 流量控制
+
+**必要性: 针对流量敏感的服务器，做双保险。**      
 
 > 基本原则: SERVER的发送速率不能超过ADSL下行带宽，否则只会浪费您的服务器带宽。  
 
@@ -164,45 +240,8 @@ root@kcptun:~#
 ```
 其中eth0为网卡，有些服务器为ens3，有些为p2p1，通过ifconfig查询修改。
 
+### SNMP
 
-### *DSCP* :lollipop: 
-DSCP差分服务代码点（Differentiated Services Code Point），IETF于1998年12月发布了Diff-Serv（Differentiated Service）的QoS分类标准。它在每个数据包IP头部的服务类别TOS标识字节中，利用已使用的6比特和未使用的2比特，通过编码值来区分优先级。     
-常用DSCP值可以参考[Wikipedia DSCP](https://en.wikipedia.org/wiki/Differentiated_services#Commonly_used_DSCP_values)，至于有没有用，完全取决于数据包经过的设备。 
-
-通过 ```-dscp ``` 参数指定dscp值，两端可分别设定。
-
-### *前向纠错* :lollipop: 
-前向纠错采用Reed Solomon纠删码, 它的基本原理如下： 给定n个数据块d1, d2,…, dn，n和一个正整数m， RS根据n个数据块生成m个校验块， c1, c2,…, cm。 对于任意的n和m， 从n个原始数据块和m 个校验块中任取n块就能解码出原始数据， 即RS最多容忍m个数据块或者校验块同时丢失。
-
-![reed-solomon](rs.png)
-
-通过参数```-datashard 10 -parityshard 3``` 在两端同时设定。
-
-### *Snappy数据流压缩* :lollipop: 
-> Snappy is a compression/decompression library. It does not aim for maximum
-> compression, or compatibility with any other compression library; instead,
-> it aims for very high speeds and reasonable compression. For instance,
-> compared to the fastest mode of zlib, Snappy is an order of magnitude faster
-> for most inputs, but the resulting compressed files are anywhere from 20% to
-> 100% bigger.
-
-> Reference: http://google.github.io/snappy/
-
-通过参数 ```-nocomp``` 在两端同时设定以关闭压缩。
-> 提示: 关闭压缩可能会降低延迟。
-
-### *内置模式* :lollipop: 
-响应速度:     
-*fast3 >* ***[fast2]*** *> fast > normal > default*        
-有效载荷比:     
-*default > normal > fast >* ***[fast2]*** *> fast3*       
-中间mode参数比较均衡，总之就是越快越浪费带宽，推荐模式 ***fast2***         
-更高级的 ***手动档*** 需要理解KCP协议，并通过 ***隐藏参数*** 调整，例如:
-```
- -mode manual -nodelay 1 -resend 2 -nc 1 -interval 20
-```
-
-### *SNMP* :lollipop:
 ```go
 // Snmp defines network statistics indicator
 type Snmp struct {
@@ -228,32 +267,75 @@ type Snmp struct {
 }
 ```
 
-使用```kill -SIGUSR1 pid``` 可以在控制台打印出SNMP信息，通常用于精细调整***当前链路的有效载荷比***。        
-观察```RetransSegs,FastRetransSegs,LostSegs,OutSegs```这几者的数值比例，用于参考调整```-mode manual,fec```的参数。        
+使用```kill -SIGUSR1 pid``` 可以在控制台打印出SNMP信息，通常用于精细调整**当前链路的有效载荷比**。        
+观察```RetransSegs,FastRetransSegs,LostSegs,OutSegs```这几者的数值比例，用于参考调整```-mode manual,fec```的参数。    
 
-### *故障排除* :lollipop:
-> Q: 客户端和服务器端***皆无*** ```stream opened```信息。       
+#### 带宽计算公式
+
+```
+在不丢包的情况下，有最大-rcvwnd 个数据包在网络上正在向你传输，以平均数据包大小avgsize计算，在任意时刻，有：     
+
+		network_cap = rcvwnd*avgsize
+
+数据流向你，这个值再除以ping值(rtt)，等于最大带宽使用量。
+
+		max_bandwidth = network_cap/rtt = rcvwnd*avgsize/rtt
+		
+举例，设rcvwnd = 1024, avgsize = 1KB, rtt = 400ms，则：
+
+		max_bandwidth = 1024 * 1KB / 400ms = 2.5MB/s ~= 25Mbps
+		
+（注：以上计算不包括前向纠错的数据量）
+
+前向纠错是最大带宽量的一个固定比例增加：
+
+		max_bandwidth_fec = max_bandwidth*(datashard+parityshard)/datashard
+
+举例，设datashard = 10 , partiyshard = 3，则：
+
+		max_bandwidth_fec = max_bandwidth * (10 + 3) /10 = 1.3*max_bandwidth ＝ 1.3 * 25Mbps = 32.5Mbps
+```
+
+### 故障排除
+
+> Q: 客户端和服务器端**皆无** ```stream opened```信息。       
 > A: 连接客户端程序的端口设置错误。     
 
 > Q: 客户端有 ```stream opened```信息，服务器端没有。     
 > A: 连接服务器的端口设置错误，或者被防火墙拦截。     
 
-> Q: 客户端服务器***皆有*** ```stream opened```信息，但无法通信。      
+> Q: 客户端服务器**皆有** ```stream opened```信息，但无法通信。      
 > A: 上层软件的设定错误。     
 
-### *免责申明* :warning:
-用户以各种方式使用本软件（包括但不限于修改使用、直接使用、通过第三方使用）的过程中，不得以任何方式利用本软件直接或间接从事违反中国法律、以及社会公德的行为。软件的使用者需对自身行为负责，因使用软件引发的一切纠纷，由使用者承担全部法律及连带责任。作者不承担任何法律及连带责任。       
+### 免责申明
 
-对免责声明的解释、修改及更新权均属于作者本人所有。
+**用户以各种方式使用本软件（包括但不限于修改使用、直接使用、通过第三方使用）的过程中，不得以任何方式利用本软件直接或间接从事违反中国法律、以及社会公德的行为。软件的使用者需对自身行为负责，因使用软件引发的一切纠纷，由使用者承担全部法律及连带责任。作者不承担任何法律及连带责任。**       
+
+**对免责声明的解释、修改及更新权均属于作者本人所有。**
+
+### 捐赠
 
-### *捐赠* :dollar:
 ![donate](donate.png)          
 
-对该项目的捐款将用于[gonet/2](http://gonet2.github.io/)游戏服务器框架的研发。     
+### 特别鸣谢
 
-```特别感谢: 郑H立, 南D风, Li, 七q, 凌J，昶，Les*ables, Ky*n, 噼**啦, 等，名字已做特殊处理。```
+> 郑H立, 南东风, Li, 七七, 凌君, 昶，LesMiserables, KyOn, 噼里啪啦, 继斌, 小苍辛苦, **Ken**, 
+> 乔槁, 佳晨, 猪肉佬, lcx, 昊文, 冰峰, 凡, alex, **海豹叔叔**, 奥姐, 张冰, 司成, 
+> 武子, **慎**，Alex43211，**Coxxs**，荣，NeroNg，吴骁，定一，我不是林J，Patrick, 超, 陈，windfarer, 宇,
+> 今晶，斌，晓东，最后一缕阳光。
+
+好人一生平安!
+
+### 相关软件
+
+1. https://github.com/bettermanbao/openwrt-kcptun
+2. https://github.com/EasyPi/openwrt-kcptun
+3. https://github.com/kuoruan/luci-app-kcptun
+4. https://github.com/dfdragon/kcptun_gclient
+5. https://github.com/dfdragon/kcptun_xclient
+
+### 参考资料
 
-### *参考资料* :paperclip:
 1. https://github.com/skywind3000/kcp -- KCP - A Fast and Reliable ARQ Protocol.
 2. https://github.com/klauspost/reedsolomon -- Reed-Solomon Erasure Coding in Go.
 3. https://en.wikipedia.org/wiki/Differentiated_services -- DSCP.
@@ -267,3 +349,4 @@ type Snmp struct {
 11. https://tools.ietf.org/html/rfc5827 -- Early Retransmit for TCP and Stream Control Transmission Protocol (SCTP).
 12. http://http2.github.io/ -- What is HTTP/2?
 13. http://www.lartc.org/LARTC-zh_CN.GB2312.pdf -- Linux Advanced Routing & Traffic Control
+14. https://en.wikipedia.org/wiki/Noisy-channel_coding_theorem -- Noisy channel coding theorem

build-release.sh

@@ -12,6 +12,7 @@ fi
 
 VERSION=`date -u +%Y%m%d`
 LDFLAGS="-X main.VERSION=$VERSION -s -w"
+GCFLAGS=""
 
 OSES=(linux darwin windows freebsd)
 ARCHS=(amd64 386)
@@ -22,8 +23,8 @@ for os in ${OSES[@]}; do
 		then
 			suffix=".exe"
 		fi
-		env CGO_ENABLED=0 GOOS=$os GOARCH=$arch go build -ldflags "$LDFLAGS" -o client_${os}_${arch}${suffix} github.com/xtaci/kcptun/client
-		env CGO_ENABLED=0 GOOS=$os GOARCH=$arch go build -ldflags "$LDFLAGS" -o server_${os}_${arch}${suffix} github.com/xtaci/kcptun/server
+		env CGO_ENABLED=0 GOOS=$os GOARCH=$arch go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_${os}_${arch}${suffix} github.com/xtaci/kcptun/client
+		env CGO_ENABLED=0 GOOS=$os GOARCH=$arch go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_${os}_${arch}${suffix} github.com/xtaci/kcptun/server
 		if $UPX; then upx -9 client_${os}_${arch}${suffix} server_${os}_${arch}${suffix};fi
 		tar -zcf kcptun-${os}-${arch}-$VERSION.tar.gz client_${os}_${arch}${suffix} server_${os}_${arch}${suffix}
 		$MD5 kcptun-${os}-${arch}-$VERSION.tar.gz
@@ -33,9 +34,21 @@ done
 # ARM
 ARMS=(5 6 7)
 for v in ${ARMS[@]}; do
-	env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=$v go build -ldflags "$LDFLAGS" -o client_linux_arm$v  github.com/xtaci/kcptun/client
-	env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=$v go build -ldflags "$LDFLAGS" -o server_linux_arm$v  github.com/xtaci/kcptun/server
+	env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=$v go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_linux_arm$v  github.com/xtaci/kcptun/client
+	env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=$v go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_linux_arm$v  github.com/xtaci/kcptun/server
 done
 if $UPX; then upx -9 client_linux_arm* server_linux_arm*;fi
 tar -zcf kcptun-linux-arm-$VERSION.tar.gz client_linux_arm* server_linux_arm*
 $MD5 kcptun-linux-arm-$VERSION.tar.gz
+
+#MIPS32LE
+env CGO_ENABLED=0 GOOS=linux GOARCH=mipsle go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_linux_mipsle github.com/xtaci/kcptun/client
+env CGO_ENABLED=0 GOOS=linux GOARCH=mipsle go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_linux_mipsle github.com/xtaci/kcptun/server
+env CGO_ENABLED=0 GOOS=linux GOARCH=mips go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_linux_mips github.com/xtaci/kcptun/client
+env CGO_ENABLED=0 GOOS=linux GOARCH=mips go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_linux_mips github.com/xtaci/kcptun/server
+
+if $UPX; then upx -9 client_linux_mips* server_linux_mips*;fi
+tar -zcf kcptun-linux-mipsle-$VERSION.tar.gz client_linux_mipsle server_linux_mipsle
+tar -zcf kcptun-linux-mips-$VERSION.tar.gz client_linux_mips server_linux_mips
+$MD5 kcptun-linux-mipsle-$VERSION.tar.gz
+$MD5 kcptun-linux-mips-$VERSION.tar.gz

client/config.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+)
+
+// Config for client
+type Config struct {
+	LocalAddr    string `json:"localaddr"`
+	RemoteAddr   string `json:"remoteaddr"`
+	Key          string `json:"key"`
+	Crypt        string `json:"crypt"`
+	Mode         string `json:"mode"`
+	Conn         int    `json:"conn"`
+	AutoExpire   int    `json:"autoexpire"`
+	MTU          int    `json:"mtu"`
+	SndWnd       int    `json:"sndwnd"`
+	RcvWnd       int    `json:"rcvwnd"`
+	DataShard    int    `json:"datashard"`
+	ParityShard  int    `json:"parityshard"`
+	DSCP         int    `json:"dscp"`
+	NoComp       bool   `json:"nocomp"`
+	AckNodelay   bool   `json:"acknodelay"`
+	NoDelay      int    `json:"nodelay"`
+	Interval     int    `json:"interval"`
+	Resend       int    `json:"resend"`
+	NoCongestion int    `json:"nc"`
+	SockBuf      int    `json:"sockbuf"`
+	KeepAlive    int    `json:"keepalive"`
+	Log          string `json:"log"`
+	SnmpLog      string `json:"snmplog"`
+	SnmpPeriod   int    `json:"snmpperiod"`
+}
+
+func parseJSONConfig(config *Config, path string) error {
+	file, err := os.Open(path) // For read access.
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	return json.NewDecoder(file).Decode(config)
+}

client/main.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"crypto/sha1"
+	"encoding/csv"
+	"fmt"
 	"io"
 	"log"
 	"math/rand"
@@ -11,10 +13,11 @@ import (
 
 	"golang.org/x/crypto/pbkdf2"
 
-	"github.com/golang/snappy"
-	"github.com/hashicorp/yamux"
+	"github.com/klauspost/compress/snappy"
+	"github.com/pkg/errors"
 	"github.com/urfave/cli"
 	kcp "github.com/xtaci/kcp-go"
+	"github.com/xtaci/smux"
 )
 
 var (
@@ -52,7 +55,12 @@ func newCompStream(conn net.Conn) *compStream {
 	return c
 }
 
-func handleClient(p1, p2 io.ReadWriteCloser) {
+func handleClient(sess *smux.Session, p1 io.ReadWriteCloser) {
+	p2, err := sess.OpenStream()
+	if err != nil {
+		return
+	}
+
 	log.Println("stream opened")
 	defer log.Println("stream closed")
 	defer p1.Close()
@@ -60,16 +68,10 @@ func handleClient(p1, p2 io.ReadWriteCloser) {
 
 	// start tunnel
 	p1die := make(chan struct{})
-	go func() {
-		io.Copy(p1, p2)
-		close(p1die)
-	}()
+	go func() { io.Copy(p1, p2); close(p1die) }()
 
 	p2die := make(chan struct{})
-	go func() {
-		io.Copy(p2, p1)
-		close(p2die)
-	}()
+	go func() { io.Copy(p2, p1); close(p2die) }()
 
 	// wait for tunnel termination
 	select {
@@ -80,7 +82,7 @@ func handleClient(p1, p2 io.ReadWriteCloser) {
 
 func checkError(err error) {
 	if err != nil {
-		log.Println(err)
+		log.Printf("%+v\n", err)
 		os.Exit(-1)
 	}
 }
@@ -93,7 +95,7 @@ func main() {
 	}
 	myApp := cli.NewApp()
 	myApp.Name = "kcptun"
-	myApp.Usage = "kcptun client"
+	myApp.Usage = "client(with SMUX)"
 	myApp.Version = VERSION
 	myApp.Flags = []cli.Flag{
 		cli.StringFlag{
@@ -109,28 +111,33 @@ func main() {
 		cli.StringFlag{
 			Name:   "key",
 			Value:  "it's a secrect",
-			Usage:  "key for communcation, must be the same as kcptun server",
+			Usage:  "pre-shared secret between client and server",
 			EnvVar: "KCPTUN_KEY",
 		},
 		cli.StringFlag{
 			Name:  "crypt",
 			Value: "aes",
-			Usage: "methods for encryption: aes, aes-128, aes-192, tea, xor, none",
+			Usage: "aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, none",
 		},
 		cli.StringFlag{
 			Name:  "mode",
 			Value: "fast",
-			Usage: "mode for communication: fast3, fast2, fast, normal",
+			Usage: "profiles: fast3, fast2, fast, normal",
 		},
 		cli.IntFlag{
 			Name:  "conn",
 			Value: 1,
-			Usage: "establish N physical connections as specified by 'conn' to server",
+			Usage: "set num of UDP connections to server",
+		},
+		cli.IntFlag{
+			Name:  "autoexpire",
+			Value: 0,
+			Usage: "set auto expiration time(in seconds) for a single UDP connection, 0 to disable",
 		},
 		cli.IntFlag{
 			Name:  "mtu",
 			Value: 1350,
-			Usage: "set MTU of UDP packets, suggest 'tracepath' to discover path mtu",
+			Usage: "set maximum transmission unit for UDP packets",
 		},
 		cli.IntFlag{
 			Name:  "sndwnd",
@@ -142,10 +149,6 @@ func main() {
 			Value: 1024,
 			Usage: "set receive window size(num of packets)",
 		},
-		cli.BoolFlag{
-			Name:  "nocomp",
-			Usage: "disable compression",
-		},
 		cli.IntFlag{
 			Name:  "datashard",
 			Value: 10,
@@ -156,16 +159,20 @@ func main() {
 			Value: 3,
 			Usage: "set reed-solomon erasure coding - parityshard",
 		},
-		cli.BoolFlag{
-			Name:   "acknodelay",
-			Usage:  "flush ack immediately when a packet is received",
-			Hidden: true,
-		},
 		cli.IntFlag{
 			Name:  "dscp",
 			Value: 0,
 			Usage: "set DSCP(6bit)",
 		},
+		cli.BoolFlag{
+			Name:  "nocomp",
+			Usage: "disable compression",
+		},
+		cli.BoolFlag{
+			Name:   "acknodelay",
+			Usage:  "flush ack immediately when a packet is received",
+			Hidden: true,
+		},
 		cli.IntFlag{
 			Name:   "nodelay",
 			Value:  0,
@@ -196,32 +203,87 @@ func main() {
 			Value:  10, // nat keepalive interval in seconds
 			Hidden: true,
 		},
+		cli.StringFlag{
+			Name:  "snmplog",
+			Value: "",
+			Usage: "collect snmp to file, aware of timeformat in golang, like: ./snmp-20060102.log",
+		},
+		cli.IntFlag{
+			Name:  "snmpperiod",
+			Value: 60,
+			Usage: "snmp collect period, in seconds",
+		},
+		cli.StringFlag{
+			Name:  "log",
+			Value: "",
+			Usage: "specify a log file to output, default goes to stderr",
+		},
+		cli.StringFlag{
+			Name:  "c",
+			Value: "", // when the value is not empty, the config path must exists
+			Usage: "config from json file, which will override the command from shell",
+		},
 	}
 	myApp.Action = func(c *cli.Context) error {
+		config := Config{}
+		config.LocalAddr = c.String("localaddr")
+		config.RemoteAddr = c.String("remoteaddr")
+		config.Key = c.String("key")
+		config.Crypt = c.String("crypt")
+		config.Mode = c.String("mode")
+		config.Conn = c.Int("conn")
+		config.AutoExpire = c.Int("autoexpire")
+		config.MTU = c.Int("mtu")
+		config.SndWnd = c.Int("sndwnd")
+		config.RcvWnd = c.Int("rcvwnd")
+		config.DataShard = c.Int("datashard")
+		config.ParityShard = c.Int("parityshard")
+		config.DSCP = c.Int("dscp")
+		config.NoComp = c.Bool("nocomp")
+		config.AckNodelay = c.Bool("acknodelay")
+		config.NoDelay = c.Int("nodelay")
+		config.Interval = c.Int("interval")
+		config.Resend = c.Int("resend")
+		config.NoCongestion = c.Int("nc")
+		config.SockBuf = c.Int("sockbuf")
+		config.KeepAlive = c.Int("keepalive")
+		config.Log = c.String("log")
+		config.SnmpLog = c.String("snmplog")
+		config.SnmpPeriod = c.Int("snmpperiod")
+
+		if c.String("c") != "" {
+			err := parseJSONConfig(&config, c.String("c"))
+			checkError(err)
+		}
+
+		// log redirect
+		if config.Log != "" {
+			f, err := os.OpenFile(config.Log, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			checkError(err)
+			defer f.Close()
+			log.SetOutput(f)
+		}
+
+		switch config.Mode {
+		case "normal":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 30, 2, 1
+		case "fast":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 20, 2, 1
+		case "fast2":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 1, 20, 2, 1
+		case "fast3":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 1, 10, 2, 1
+		}
+
 		log.Println("version:", VERSION)
-		addr, err := net.ResolveTCPAddr("tcp", c.String("localaddr"))
+		addr, err := net.ResolveTCPAddr("tcp", config.LocalAddr)
 		checkError(err)
 		listener, err := net.ListenTCP("tcp", addr)
 		checkError(err)
 
-		// kcp server
-		nodelay, interval, resend, nc := c.Int("nodelay"), c.Int("interval"), c.Int("resend"), c.Int("nc")
-
-		switch c.String("mode") {
-		case "normal":
-			nodelay, interval, resend, nc = 0, 30, 2, 1
-		case "fast":
-			nodelay, interval, resend, nc = 0, 20, 2, 1
-		case "fast2":
-			nodelay, interval, resend, nc = 1, 20, 2, 1
-		case "fast3":
-			nodelay, interval, resend, nc = 1, 10, 2, 1
-		}
-
-		crypt := c.String("crypt")
-		pass := pbkdf2.Key([]byte(c.String("key")), []byte(SALT), 4096, 32, sha1.New)
+		pass := pbkdf2.Key([]byte(config.Key), []byte(SALT), 4096, 32, sha1.New)
 		var block kcp.BlockCrypt
-		switch c.String("crypt") {
+		switch config.Crypt {
 		case "tea":
 			block, _ = kcp.NewTEABlockCrypt(pass[:16])
 		case "xor":
@@ -232,91 +294,194 @@ func main() {
 			block, _ = kcp.NewAESBlockCrypt(pass[:16])
 		case "aes-192":
 			block, _ = kcp.NewAESBlockCrypt(pass[:24])
+		case "blowfish":
+			block, _ = kcp.NewBlowfishBlockCrypt(pass)
+		case "twofish":
+			block, _ = kcp.NewTwofishBlockCrypt(pass)
+		case "cast5":
+			block, _ = kcp.NewCast5BlockCrypt(pass[:16])
+		case "3des":
+			block, _ = kcp.NewTripleDESBlockCrypt(pass[:24])
+		case "xtea":
+			block, _ = kcp.NewXTEABlockCrypt(pass[:16])
+		case "salsa20":
+			block, _ = kcp.NewSalsa20BlockCrypt(pass)
 		default:
+			config.Crypt = "aes"
 			block, _ = kcp.NewAESBlockCrypt(pass)
 		}
 
-		remoteaddr := c.String("remoteaddr")
-		datashard, parityshard := c.Int("datashard"), c.Int("parityshard")
-		mtu, sndwnd, rcvwnd := c.Int("mtu"), c.Int("sndwnd"), c.Int("rcvwnd")
-		nocomp, acknodelay := c.Bool("nocomp"), c.Bool("acknodelay")
-		dscp, sockbuf, keepalive, conn := c.Int("dscp"), c.Int("sockbuf"), c.Int("keepalive"), c.Int("conn")
-
 		log.Println("listening on:", listener.Addr())
-		log.Println("encryption:", crypt)
-		log.Println("nodelay parameters:", nodelay, interval, resend, nc)
-		log.Println("remote address:", remoteaddr)
-		log.Println("sndwnd:", sndwnd, "rcvwnd:", rcvwnd)
-		log.Println("compression:", !nocomp)
-		log.Println("mtu:", mtu)
-		log.Println("datashard:", datashard, "parityshard:", parityshard)
-		log.Println("acknodelay:", acknodelay)
-		log.Println("dscp:", dscp)
-		log.Println("sockbuf:", sockbuf)
-		log.Println("keepalive:", keepalive)
-		log.Println("conn:", conn)
+		log.Println("encryption:", config.Crypt)
+		log.Println("nodelay parameters:", config.NoDelay, config.Interval, config.Resend, config.NoCongestion)
+		log.Println("remote address:", config.RemoteAddr)
+		log.Println("sndwnd:", config.SndWnd, "rcvwnd:", config.RcvWnd)
+		log.Println("compression:", !config.NoComp)
+		log.Println("mtu:", config.MTU)
+		log.Println("datashard:", config.DataShard, "parityshard:", config.ParityShard)
+		log.Println("acknodelay:", config.AckNodelay)
+		log.Println("dscp:", config.DSCP)
+		log.Println("sockbuf:", config.SockBuf)
+		log.Println("keepalive:", config.KeepAlive)
+		log.Println("conn:", config.Conn)
+		log.Println("autoexpire:", config.AutoExpire)
+		log.Println("snmplog:", config.SnmpLog)
+		log.Println("snmpperiod:", config.SnmpPeriod)
 
-		config := &yamux.Config{
-			AcceptBacklog:          256,
-			EnableKeepAlive:        true,
-			KeepAliveInterval:      30 * time.Second,
-			ConnectionWriteTimeout: 30 * time.Second,
-			MaxStreamWindowSize:    uint32(sockbuf),
-			LogOutput:              os.Stderr,
-		}
-		createConn := func() *yamux.Session {
-			kcpconn, err := kcp.DialWithOptions(remoteaddr, block, datashard, parityshard)
-			checkError(err)
+		smuxConfig := smux.DefaultConfig()
+		smuxConfig.MaxReceiveBuffer = config.SockBuf
+
+		createConn := func() (*smux.Session, error) {
+			kcpconn, err := kcp.DialWithOptions(config.RemoteAddr, block, config.DataShard, config.ParityShard)
+			if err != nil {
+				return nil, errors.Wrap(err, "createConn()")
+			}
 			kcpconn.SetStreamMode(true)
-			kcpconn.SetNoDelay(nodelay, interval, resend, nc)
-			kcpconn.SetWindowSize(sndwnd, rcvwnd)
-			kcpconn.SetMtu(mtu)
-			kcpconn.SetACKNoDelay(acknodelay)
-			kcpconn.SetKeepAlive(keepalive)
+			kcpconn.SetNoDelay(config.NoDelay, config.Interval, config.Resend, config.NoCongestion)
+			kcpconn.SetWindowSize(config.SndWnd, config.RcvWnd)
+			kcpconn.SetMtu(config.MTU)
+			kcpconn.SetACKNoDelay(config.AckNodelay)
+			kcpconn.SetKeepAlive(config.KeepAlive)
 
-			if err := kcpconn.SetDSCP(dscp); err != nil {
+			if err := kcpconn.SetDSCP(config.DSCP); err != nil {
 				log.Println("SetDSCP:", err)
 			}
-			if err := kcpconn.SetReadBuffer(sockbuf); err != nil {
+			if err := kcpconn.SetReadBuffer(config.SockBuf); err != nil {
 				log.Println("SetReadBuffer:", err)
 			}
-			if err := kcpconn.SetWriteBuffer(sockbuf); err != nil {
+			if err := kcpconn.SetWriteBuffer(config.SockBuf); err != nil {
 				log.Println("SetWriteBuffer:", err)
 			}
 
 			// stream multiplex
-			var session *yamux.Session
-			if nocomp {
-				session, err = yamux.Client(kcpconn, config)
+			var session *smux.Session
+			if config.NoComp {
+				session, err = smux.Client(kcpconn, smuxConfig)
 			} else {
-				session, err = yamux.Client(newCompStream(kcpconn), config)
+				session, err = smux.Client(newCompStream(kcpconn), smuxConfig)
 			}
+			if err != nil {
+				return nil, errors.Wrap(err, "createConn()")
+			}
+			return session, nil
+		}
+
+		// wait until a connection is ready
+		waitConn := func() *smux.Session {
+			for {
+				if session, err := createConn(); err == nil {
+					return session
+				} else {
+					time.Sleep(time.Second)
+				}
+			}
+		}
+
+		numconn := uint16(config.Conn)
+		muxes := make([]struct {
+			session *smux.Session
+			ttl     time.Time
+		}, numconn)
+
+		for k := range muxes {
+			sess, err := createConn()
 			checkError(err)
-			return session
-		}
-
-		numconn := uint16(conn)
-		var muxes []*yamux.Session
-		for i := uint16(0); i < numconn; i++ {
-			muxes = append(muxes, createConn())
+			muxes[k].session = sess
+			muxes[k].ttl = time.Now().Add(time.Duration(config.AutoExpire) * time.Second)
 		}
 
+		chScavenger := make(chan *smux.Session, 128)
+		go scavenger(chScavenger)
+		go snmpLogger(config.SnmpLog, config.SnmpPeriod)
 		rr := uint16(0)
 		for {
 			p1, err := listener.AcceptTCP()
-			checkError(err)
-			mux := muxes[rr%numconn]
-			p2, err := mux.Open()
-			if err != nil { // yamux failure
-				log.Println(err)
-				p1.Close()
-				muxes[rr%numconn] = createConn()
-				mux.Close()
-				continue
+			if err != nil {
+				log.Fatalln(err)
 			}
-			go handleClient(p1, p2)
+			if err := p1.SetReadBuffer(config.SockBuf); err != nil {
+				log.Println("TCP SetReadBuffer:", err)
+			}
+			if err := p1.SetWriteBuffer(config.SockBuf); err != nil {
+				log.Println("TCP SetWriteBuffer:", err)
+			}
+			checkError(err)
+			idx := rr % numconn
+
+			// do auto expiration && reconnection
+			if muxes[idx].session.IsClosed() || (config.AutoExpire > 0 && time.Now().After(muxes[idx].ttl)) {
+				chScavenger <- muxes[idx].session
+				muxes[idx].session = waitConn()
+				muxes[idx].ttl = time.Now().Add(time.Duration(config.AutoExpire) * time.Second)
+			}
+
+			go handleClient(muxes[idx].session, p1)
 			rr++
 		}
 	}
 	myApp.Run(os.Args)
 }
+
+type scavengeSession struct {
+	session *smux.Session
+	ttl     time.Time
+}
+
+const (
+	maxScavengeTTL = 10 * time.Minute
+)
+
+func scavenger(ch chan *smux.Session) {
+	ticker := time.NewTicker(30 * time.Second)
+	defer ticker.Stop()
+	var sessionList []scavengeSession
+	for {
+		select {
+		case sess := <-ch:
+			sessionList = append(sessionList, scavengeSession{sess, time.Now()})
+		case <-ticker.C:
+			var newList []scavengeSession
+			for k := range sessionList {
+				s := sessionList[k]
+				if s.session.NumStreams() == 0 || s.session.IsClosed() || time.Since(s.ttl) > maxScavengeTTL {
+					log.Println("session scavenged")
+					s.session.Close()
+				} else {
+					newList = append(newList, sessionList[k])
+				}
+			}
+			sessionList = newList
+		}
+	}
+}
+
+func snmpLogger(path string, interval int) {
+	if path == "" || interval == 0 {
+		return
+	}
+	ticker := time.NewTicker(time.Duration(interval) * time.Second)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			f, err := os.OpenFile(time.Now().Format(path), os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			if err != nil {
+				log.Println(err)
+				return
+			}
+			w := csv.NewWriter(f)
+			// write header in empty file
+			if stat, err := f.Stat(); err == nil && stat.Size() == 0 {
+				if err := w.Write(append([]string{"Unix"}, kcp.DefaultSnmp.Header()...)); err != nil {
+					log.Println(err)
+				}
+			}
+			if err := w.Write(append([]string{fmt.Sprint(time.Now().Unix())}, kcp.DefaultSnmp.ToSlice()...)); err != nil {
+				log.Println(err)
+			}
+			kcp.DefaultSnmp.Reset()
+			w.Flush()
+			f.Close()
+		}
+	}
+}

server/config.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+)
+
+// Config for server
+type Config struct {
+	Listen       string `json:"listen"`
+	Target       string `json:"target"`
+	Key          string `json:"key"`
+	Crypt        string `json:"crypt"`
+	Mode         string `json:"mode"`
+	MTU          int    `json:"mtu"`
+	SndWnd       int    `json:"sndwnd"`
+	RcvWnd       int    `json:"rcvwnd"`
+	DataShard    int    `json:"datashard"`
+	ParityShard  int    `json:"parityshard"`
+	DSCP         int    `json:"dscp"`
+	NoComp       bool   `json:"nocomp"`
+	AckNodelay   bool   `json:"acknodelay"`
+	NoDelay      int    `json:"nodelay"`
+	Interval     int    `json:"interval"`
+	Resend       int    `json:"resend"`
+	NoCongestion int    `json:"nc"`
+	SockBuf      int    `json:"sockbuf"`
+	KeepAlive    int    `json:"keepalive"`
+	Log          string `json:"log"`
+	SnmpLog      string `json:"snmplog"`
+	SnmpPeriod   int    `json:"snmpperiod"`
+}
+
+func parseJSONConfig(config *Config, path string) error {
+	file, err := os.Open(path) // For read access.
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	return json.NewDecoder(file).Decode(config)
+}

server/main.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"crypto/sha1"
+	"encoding/csv"
+	"fmt"
 	"io"
 	"log"
 	"math/rand"
@@ -11,10 +13,10 @@ import (
 
 	"golang.org/x/crypto/pbkdf2"
 
-	"github.com/golang/snappy"
-	"github.com/hashicorp/yamux"
+	"github.com/klauspost/compress/snappy"
 	"github.com/urfave/cli"
 	kcp "github.com/xtaci/kcp-go"
+	"github.com/xtaci/smux"
 )
 
 var (
@@ -53,25 +55,33 @@ func newCompStream(conn net.Conn) *compStream {
 }
 
 // handle multiplex-ed connection
-func handleMux(conn io.ReadWriteCloser, target string, config *yamux.Config) {
+func handleMux(conn io.ReadWriteCloser, config *Config) {
 	// stream multiplex
-	mux, err := yamux.Server(conn, config)
+	smuxConfig := smux.DefaultConfig()
+	smuxConfig.MaxReceiveBuffer = config.SockBuf
+	mux, err := smux.Server(conn, smuxConfig)
 	if err != nil {
 		log.Println(err)
 		return
 	}
 	defer mux.Close()
-
 	for {
-		p1, err := mux.Accept()
+		p1, err := mux.AcceptStream()
 		if err != nil {
 			log.Println(err)
 			return
 		}
-		p2, err := net.DialTimeout("tcp", target, 5*time.Second)
+		p2, err := net.DialTimeout("tcp", config.Target, 5*time.Second)
 		if err != nil {
+			p1.Close()
 			log.Println(err)
-			return
+			continue
+		}
+		if err := p2.(*net.TCPConn).SetReadBuffer(config.SockBuf); err != nil {
+			log.Println("TCP SetReadBuffer:", err)
+		}
+		if err := p2.(*net.TCPConn).SetWriteBuffer(config.SockBuf); err != nil {
+			log.Println("TCP SetWriteBuffer:", err)
 		}
 		go handleClient(p1, p2)
 	}
@@ -85,16 +95,10 @@ func handleClient(p1, p2 io.ReadWriteCloser) {
 
 	// start tunnel
 	p1die := make(chan struct{})
-	go func() {
-		io.Copy(p1, p2)
-		close(p1die)
-	}()
+	go func() { io.Copy(p1, p2); close(p1die) }()
 
 	p2die := make(chan struct{})
-	go func() {
-		io.Copy(p2, p1)
-		close(p2die)
-	}()
+	go func() { io.Copy(p2, p1); close(p2die) }()
 
 	// wait for tunnel termination
 	select {
@@ -103,6 +107,13 @@ func handleClient(p1, p2 io.ReadWriteCloser) {
 	}
 }
 
+func checkError(err error) {
+	if err != nil {
+		log.Printf("%+v\n", err)
+		os.Exit(-1)
+	}
+}
+
 func main() {
 	rand.Seed(int64(time.Now().Nanosecond()))
 	if VERSION == "SELFBUILD" {
@@ -111,7 +122,7 @@ func main() {
 	}
 	myApp := cli.NewApp()
 	myApp.Name = "kcptun"
-	myApp.Usage = "kcptun server"
+	myApp.Usage = "server(with SMUX)"
 	myApp.Version = VERSION
 	myApp.Flags = []cli.Flag{
 		cli.StringFlag{
@@ -127,23 +138,23 @@ func main() {
 		cli.StringFlag{
 			Name:   "key",
 			Value:  "it's a secrect",
-			Usage:  "key for communcation, must be the same as kcptun client",
+			Usage:  "pre-shared secret between client and server",
 			EnvVar: "KCPTUN_KEY",
 		},
 		cli.StringFlag{
 			Name:  "crypt",
 			Value: "aes",
-			Usage: "methods for encryption: aes, aes-128, aes-192, tea, xor, none",
+			Usage: "aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, none",
 		},
 		cli.StringFlag{
 			Name:  "mode",
 			Value: "fast",
-			Usage: "mode for communication: fast3, fast2, fast, normal",
+			Usage: "profiles: fast3, fast2, fast, normal",
 		},
 		cli.IntFlag{
 			Name:  "mtu",
 			Value: 1350,
-			Usage: "set MTU of UDP packets, suggest 'tracepath' to discover path mtu",
+			Usage: "set maximum transmission unit for UDP packets",
 		},
 		cli.IntFlag{
 			Name:  "sndwnd",
@@ -155,10 +166,6 @@ func main() {
 			Value: 1024,
 			Usage: "set receive window size(num of packets)",
 		},
-		cli.BoolFlag{
-			Name:  "nocomp",
-			Usage: "disable compression",
-		},
 		cli.IntFlag{
 			Name:  "datashard",
 			Value: 10,
@@ -169,16 +176,20 @@ func main() {
 			Value: 3,
 			Usage: "set reed-solomon erasure coding - parityshard",
 		},
-		cli.BoolFlag{
-			Name:   "acknodelay",
-			Usage:  "flush ack immediately when a packet is received",
-			Hidden: true,
-		},
 		cli.IntFlag{
 			Name:  "dscp",
 			Value: 0,
 			Usage: "set DSCP(6bit)",
 		},
+		cli.BoolFlag{
+			Name:  "nocomp",
+			Usage: "disable compression",
+		},
+		cli.BoolFlag{
+			Name:   "acknodelay",
+			Usage:  "flush ack immediately when a packet is received",
+			Hidden: true,
+		},
 		cli.IntFlag{
 			Name:   "nodelay",
 			Value:  0,
@@ -209,25 +220,81 @@ func main() {
 			Value:  10, // nat keepalive interval in seconds
 			Hidden: true,
 		},
+		cli.StringFlag{
+			Name:  "snmplog",
+			Value: "",
+			Usage: "collect snmp to file, aware of timeformat in golang, like: ./snmp-20060102.log",
+		},
+		cli.IntFlag{
+			Name:  "snmpperiod",
+			Value: 60,
+			Usage: "snmp collect period, in seconds",
+		},
+		cli.StringFlag{
+			Name:  "log",
+			Value: "",
+			Usage: "specify a log file to output, default goes to stderr",
+		},
+		cli.StringFlag{
+			Name:  "c",
+			Value: "", // when the value is not empty, the config path must exists
+			Usage: "config from json file, which will override the command from shell",
+		},
 	}
 	myApp.Action = func(c *cli.Context) error {
-		log.Println("version:", VERSION)
-		nodelay, interval, resend, nc := c.Int("nodelay"), c.Int("interval"), c.Int("resend"), c.Int("nc")
-		switch c.String("mode") {
-		case "normal":
-			nodelay, interval, resend, nc = 0, 30, 2, 1
-		case "fast":
-			nodelay, interval, resend, nc = 0, 20, 2, 1
-		case "fast2":
-			nodelay, interval, resend, nc = 1, 20, 2, 1
-		case "fast3":
-			nodelay, interval, resend, nc = 1, 10, 2, 1
+		config := Config{}
+		config.Listen = c.String("listen")
+		config.Target = c.String("target")
+		config.Key = c.String("key")
+		config.Crypt = c.String("crypt")
+		config.Mode = c.String("mode")
+		config.MTU = c.Int("mtu")
+		config.SndWnd = c.Int("sndwnd")
+		config.RcvWnd = c.Int("rcvwnd")
+		config.DataShard = c.Int("datashard")
+		config.ParityShard = c.Int("parityshard")
+		config.DSCP = c.Int("dscp")
+		config.NoComp = c.Bool("nocomp")
+		config.AckNodelay = c.Bool("acknodelay")
+		config.NoDelay = c.Int("nodelay")
+		config.Interval = c.Int("interval")
+		config.Resend = c.Int("resend")
+		config.NoCongestion = c.Int("nc")
+		config.SockBuf = c.Int("sockbuf")
+		config.KeepAlive = c.Int("keepalive")
+		config.Log = c.String("log")
+		config.SnmpLog = c.String("snmplog")
+		config.SnmpPeriod = c.Int("snmpperiod")
+
+		if c.String("c") != "" {
+			//Now only support json config file
+			err := parseJSONConfig(&config, c.String("c"))
+			checkError(err)
 		}
 
-		crypt := c.String("crypt")
-		pass := pbkdf2.Key([]byte(c.String("key")), []byte(SALT), 4096, 32, sha1.New)
+		// log redirect
+		if config.Log != "" {
+			f, err := os.OpenFile(config.Log, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			checkError(err)
+			defer f.Close()
+			log.SetOutput(f)
+		}
+
+		switch config.Mode {
+		case "normal":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 30, 2, 1
+		case "fast":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 20, 2, 1
+		case "fast2":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 1, 20, 2, 1
+		case "fast3":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 1, 10, 2, 1
+		}
+
+		log.Println("version:", VERSION)
+		pass := pbkdf2.Key([]byte(config.Key), []byte(SALT), 4096, 32, sha1.New)
 		var block kcp.BlockCrypt
-		switch crypt {
+		switch config.Crypt {
 		case "tea":
 			block, _ = kcp.NewTEABlockCrypt(pass[:16])
 		case "xor":
@@ -238,69 +305,101 @@ func main() {
 			block, _ = kcp.NewAESBlockCrypt(pass[:16])
 		case "aes-192":
 			block, _ = kcp.NewAESBlockCrypt(pass[:24])
+		case "blowfish":
+			block, _ = kcp.NewBlowfishBlockCrypt(pass)
+		case "twofish":
+			block, _ = kcp.NewTwofishBlockCrypt(pass)
+		case "cast5":
+			block, _ = kcp.NewCast5BlockCrypt(pass[:16])
+		case "3des":
+			block, _ = kcp.NewTripleDESBlockCrypt(pass[:24])
+		case "xtea":
+			block, _ = kcp.NewXTEABlockCrypt(pass[:16])
+		case "salsa20":
+			block, _ = kcp.NewSalsa20BlockCrypt(pass)
 		default:
+			config.Crypt = "aes"
 			block, _ = kcp.NewAESBlockCrypt(pass)
 		}
 
-		datashard, parityshard := c.Int("datashard"), c.Int("parityshard")
-		lis, err := kcp.ListenWithOptions(c.String("listen"), block, datashard, parityshard)
-		if err != nil {
-			log.Fatal(err)
-		}
+		lis, err := kcp.ListenWithOptions(config.Listen, block, config.DataShard, config.ParityShard)
+		checkError(err)
+		log.Println("listening on:", lis.Addr())
+		log.Println("target:", config.Target)
+		log.Println("encryption:", config.Crypt)
+		log.Println("nodelay parameters:", config.NoDelay, config.Interval, config.Resend, config.NoCongestion)
+		log.Println("sndwnd:", config.SndWnd, "rcvwnd:", config.RcvWnd)
+		log.Println("compression:", !config.NoComp)
+		log.Println("mtu:", config.MTU)
+		log.Println("datashard:", config.DataShard, "parityshard:", config.ParityShard)
+		log.Println("acknodelay:", config.AckNodelay)
+		log.Println("dscp:", config.DSCP)
+		log.Println("sockbuf:", config.SockBuf)
+		log.Println("keepalive:", config.KeepAlive)
+		log.Println("snmplog:", config.SnmpLog)
+		log.Println("snmpperiod:", config.SnmpPeriod)
 
-		mtu, sndwnd, rcvwnd := c.Int("mtu"), c.Int("sndwnd"), c.Int("rcvwnd")
-		nocomp, acknodelay := c.Bool("nocomp"), c.Bool("acknodelay")
-		dscp, sockbuf, keepalive := c.Int("dscp"), c.Int("sockbuf"), c.Int("keepalive")
-		target := c.String("target")
-
-		log.Println("listening on ", lis.Addr())
-		log.Println("encryption:", crypt)
-		log.Println("nodelay parameters:", nodelay, interval, resend, nc)
-		log.Println("sndwnd:", sndwnd, "rcvwnd:", rcvwnd)
-		log.Println("compression:", !nocomp)
-		log.Println("mtu:", mtu)
-		log.Println("datashard:", datashard, "parityshard:", parityshard)
-		log.Println("acknodelay:", acknodelay)
-		log.Println("dscp:", dscp)
-		log.Println("sockbuf:", sockbuf)
-		log.Println("keepalive:", keepalive)
-
-		if err := lis.SetDSCP(dscp); err != nil {
+		if err := lis.SetDSCP(config.DSCP); err != nil {
 			log.Println("SetDSCP:", err)
 		}
-		if err := lis.SetReadBuffer(sockbuf); err != nil {
+		if err := lis.SetReadBuffer(config.SockBuf); err != nil {
 			log.Println("SetReadBuffer:", err)
 		}
-		if err := lis.SetWriteBuffer(sockbuf); err != nil {
+		if err := lis.SetWriteBuffer(config.SockBuf); err != nil {
 			log.Println("SetWriteBuffer:", err)
 		}
-		config := &yamux.Config{
-			AcceptBacklog:          256,
-			EnableKeepAlive:        true,
-			KeepAliveInterval:      30 * time.Second,
-			ConnectionWriteTimeout: 30 * time.Second,
-			MaxStreamWindowSize:    uint32(sockbuf),
-			LogOutput:              os.Stderr,
-		}
+
+		go snmpLogger(config.SnmpLog, config.SnmpPeriod)
 		for {
-			if conn, err := lis.Accept(); err == nil {
+			if conn, err := lis.AcceptKCP(); err == nil {
 				log.Println("remote address:", conn.RemoteAddr())
 				conn.SetStreamMode(true)
-				conn.SetNoDelay(nodelay, interval, resend, nc)
-				conn.SetMtu(mtu)
-				conn.SetWindowSize(sndwnd, rcvwnd)
-				conn.SetACKNoDelay(acknodelay)
-				conn.SetKeepAlive(keepalive)
+				conn.SetNoDelay(config.NoDelay, config.Interval, config.Resend, config.NoCongestion)
+				conn.SetMtu(config.MTU)
+				conn.SetWindowSize(config.SndWnd, config.RcvWnd)
+				conn.SetACKNoDelay(config.AckNodelay)
+				conn.SetKeepAlive(config.KeepAlive)
 
-				if nocomp {
-					go handleMux(conn, target, config)
+				if config.NoComp {
+					go handleMux(conn, &config)
 				} else {
-					go handleMux(newCompStream(conn), target, config)
+					go handleMux(newCompStream(conn), &config)
 				}
 			} else {
-				log.Println(err)
+				log.Printf("%+v", err)
 			}
 		}
 	}
 	myApp.Run(os.Args)
 }
+
+func snmpLogger(path string, interval int) {
+	if path == "" || interval == 0 {
+		return
+	}
+	ticker := time.NewTicker(time.Duration(interval) * time.Second)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			f, err := os.OpenFile(time.Now().Format(path), os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			if err != nil {
+				log.Println(err)
+				return
+			}
+			w := csv.NewWriter(f)
+			// write header in empty file
+			if stat, err := f.Stat(); err == nil && stat.Size() == 0 {
+				if err := w.Write(append([]string{"Unix"}, kcp.DefaultSnmp.Header()...)); err != nil {
+					log.Println(err)
+				}
+			}
+			if err := w.Write(append([]string{fmt.Sprint(time.Now().Unix())}, kcp.DefaultSnmp.ToSlice()...)); err != nil {
+				log.Println(err)
+			}
+			kcp.DefaultSnmp.Reset()
+			w.Flush()
+			f.Close()
+		}
+	}
+}