22.jpg?x-oss-process=image/auto-orient,1/quality,q_90/watermark,image_bG9nby5wbmc_eC1vc3MtcHJvY2Vzcz1pbWFnZS9yZXNpemUsUF8yMA,g_center,t_50,x_10,y_10

之前写了一篇关于CentOS7的内核优化,因为设置项的条目较多,没有一一添加注解,今天我们专门针对/etc/sysctl.conf中包含的优化设置项进行详解。

修改内核配置文件

1
vim /etc/sysctl.conf

刷新配置文件

1
sysctl -p

关IPv6

1
2
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

避免放大攻击

1
net.ipv4.icmp_echo_ignore_broadcasts = 1

开启恶意的ICMP错误消息保护

1
net.ipv4.icmp_ignore_bogus_error_responses = 1

关闭路由转发

1
2
3
net.ipv4.ip_forward = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0

开启反向路径过滤

1
2
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1

处理无源路由的包

1
2
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0

关SysRq功能

1
kernel.sysrq = 0

Core文件名添加PID作为扩展名

1
kernel.core_uses_pid = 1

开SYN洪水攻击保护

1
net.ipv4.tcp_syncookies = 1

修改消息队列长度

1
2
kernel.msgmnb = 65536
kernel.msgmax = 65536

设置最大内存共享段大小bytes

1
2
kernel.shmmax = 68719476736
kernel.shmall = 4294967296

TIME_WAIT的数量默认为180000

1
2
3
4
5
6
7
8
9
net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216

每个网络接口接收数据包速率比内核处理这些包的速率快时允许送到队列数据包的最大数目

1
net.core.netdev_max_backlog = 262144

限制仅仅是为防止简单的DoS攻击

1
net.ipv4.tcp_max_orphans = 3276800

未收到客户端确认信息的连接请求最大值

1
2
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0

内核放弃建立连接之前发送SYNACK包数量

1
net.ipv4.tcp_synack_retries = 1

内核放弃建立连接之前发送SYN包数量

1
net.ipv4.tcp_syn_retries = 1

开TIME_WAIT快速回收

1
net.ipv4.tcp_tw_recycle = 1

允许将TIME_WAIT Sockets重新用于新TCP连接

1
2
3
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1

当KeepAlive起用的时候TCP发送KeepAlive消息的频度缺省是2小时

1
net.ipv4.tcp_keepalive_time = 30

允许系统打开端口范围

1
net.ipv4.ip_local_port_range = 1024 65000

修改防火墙的表大小默认65536

1
2
net.netfilter.nf_conntrack_max = 655350
net.netfilter.nf_conntrack_tcp_timeout_established = 1200

 评论