优化 CentOS 7 或者 Ubuntu 16.04 以上版本下的 shadowsocks-libev 网络速度，让 shadowsocks-libev 轻松跑满宽带。同样适用于老版本 3.0 的 shadowsocks 优化。

如未安装 shadowsocks-libev 的可乘坐直达航班： CentOS 安装    Ubuntu 安装

一、优化吞吐量

1、新建配置文件：

sudo vi /etc/sysctl.d/local.conf

复制粘贴：

#max open files
fs.file-max = 51200
#max read buffer
net.core.rmem_max = 67108864
#max write buffer
net.core.wmem_max = 67108864
#default read buffer
net.core.rmem_default = 65536
#default write buffer
net.core.wmem_default = 65536
#max processor input queue
net.core.netdev_max_backlog = 4096
#max backlog
net.core.somaxconn = 4096
#resist SYN flood attacks
net.ipv4.tcp_syncookies = 1
#reuse timewait sockets when safe
net.ipv4.tcp_tw_reuse = 1
#turn off fast timewait sockets recycling
net.ipv4.tcp_tw_recycle = 0
#short FIN timeout
net.ipv4.tcp_fin_timeout = 30
#short keepalive time
net.ipv4.tcp_keepalive_time = 1200
#outbound port range
net.ipv4.ip_local_port_range = 10000 65000
#max SYN backlog
net.ipv4.tcp_max_syn_backlog = 4096
#max timewait sockets held by system simultaneously
net.ipv4.tcp_max_tw_buckets = 5000
#turn on TCP Fast Open on both client and server side
net.ipv4.tcp_fastopen = 3
#TCP receive buffer
net.ipv4.tcp_rmem = 4096 87380 67108864
#TCP write buffer
net.ipv4.tcp_wmem = 4096 65536 67108864
#turn on path MTU discovery
net.ipv4.tcp_mtu_probing = 1

net.ipv4.tcp_congestion_control = bbr

2、运行：

sysctl --system

3、编辑配置文件limits.conf

sudo vi /etc/security/limits.conf

在文件结尾添加两行：

* soft nofile 51200
* hard nofile 51200

4、编辑 shadowsocks-libev 服务

# 服务配置文件名称视具体而定
sudo vi /etc/systemd/system/shadowsocks-libev.service

在[Service]之后加入 ExecStartPre=/bin/sh -c ‘ulimit -n 51200’

[Unit]
Description=Shadowsocks-libev Server
After=network.target

[Service]
Type=simple
# 服务配置可能有所不一样，视实际而定
# 在这里加入 ExecStartPre=/bin/sh -c 'ulimit -n 51200'
ExecStartPre=/bin/sh -c 'ulimit -n 51200'
ExecStart=/usr/local/bin/ss-server -c /etc/shadowsocks-libev/config.json -u
Restart=on-abort

[Install]
WantedBy=multi-user.target

5、重新加载 shadowsocks-libev 服务配置

sudo systemctl daemon-reload

6、重启 Shadowsocks-libev 服务

sudo systemctl restart shadowsocks-libev

二、开启TCP Fast Open

TCP Fast Open可以降低Shadowsocks服务器和客户端的延迟。实际上在上一步已经开启了TCP Fast Open，现在只需要在Shadowsocks配置中启用TCP Fast Open。

1、编辑config.json：

sudo vi /etc/shadowsocks-libev/config.json

将 fast_open 的值由 false 修改为 true

{
     "server":"0.0.0.0",
     "server_port":8388,
     "local_port":1080,
     "password":"password",
     "timeout":600,
     "method":"aes-256-cfb",
     /*这里设置 fast_open：true，如果没有则加入*/
     "fast_open": true
 } 

2、重启 shadowsocks-libev 服务：

sudo systemctl restart shadowsocks-libev

三、最后开启 Google BBR

优化到此基本完成。