centos7系统优化-转载

禁用SELINUX

# grep -i ^selinux /etc/selinux/config
SELINUX=enforcing
SELINUXTYPE=targeted

注释掉上面2行，并增长 SELINUX=disabled。运行setenforce 0(设置SELinux 成为permissive模式,setenforce 1 设置SELinux 成为enforcing模式)，临时关闭SELINUX，经过getenforce 查看SELinux运行状态，重启电脑。

最大进程数和最大文件打开数) ：

ulimit -n和-u能够查看Linux的最大进程数和最大文件打开数，为了优化linux性能，可能须要修改这个最大值。临时修改的话ulimit -n 204800就能够了，重启后失效。
修改/etc/security/limits.conf文件，在文件末尾添加

* soft nofile 1024000
* hard nofile 1024000
* soft nproc  1024000
* hard nproc  1024000

说明：
'*' 表明针对全部用户
noproc 是表明最大进程数
nofile 是表明最大文件打开数
还须要修改/etc/security/limits.d下面的conf文件(会覆盖前面的配置信息)，个人是20-nproc.conf

# cat /etc/security/limits.d/20-nproc.conf
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.

*          soft    nproc     4096
root       soft    nproc     unlimited

修改成：

# cat /etc/security/limits.d/20-nproc.conf
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.

* soft nproc  1024000
* hard nproc  1024000

修改完重启。

内核优化：

# cat /etc/sysctl.conf
# System default settings live in /usr/lib/sysctl.d/00-system.conf.
# To override those settings, enter new settings here, or in an /etc/sysctl.d/<name>.conf file
#
# For more information, see sysctl.conf(5) and sysctl.d(5).

根据提示修改/usr/lib/sysctl.d/00-system.conf里面的内容，增长以下内容：

#关闭ipv6

net.ipv6.conf.all.disable_ipv6 = 1

net.ipv6.conf.default.disable_ipv6 = 1

# 避免放大攻击

net.ipv4.icmp_echo_ignore_broadcasts = 1

# 开启恶意icmp错误消息保护

net.ipv4.icmp_ignore_bogus_error_responses = 1

#关闭路由转发

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

net.ipv4.conf.all.rp_filter = 1

net.ipv4.conf.default.rp_filter = 1

#处理无源路由的包

net.ipv4.conf.all.accept_source_route = 0

net.ipv4.conf.default.accept_source_route = 0

#关闭sysrq功能

kernel.sysrq = 0

#core文件名中添加pid做为扩展名

kernel.core_uses_pid = 1

# 开启SYN洪水攻击保护

net.ipv4.tcp_syncookies = 1

#修改消息队列长度

kernel.msgmnb = 65536

kernel.msgmax = 65536

#设置最大内存共享段大小bytes

kernel.shmmax = 68719476736

kernel.shmall = 4294967296

#timewait的数量，默认180000

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

#每一个网络接口接收数据包的速率比内核处理这些包的速率快时，容许送到队列的数据包的最大数目

net.core.netdev_max_backlog = 262144

#限制仅仅是为了防止简单的DoS 攻击

net.ipv4.tcp_max_orphans = 3276800

#未收到客户端确认信息的链接请求的最大值

net.ipv4.tcp_max_syn_backlog = 262144

net.ipv4.tcp_timestamps = 0

#内核放弃创建链接以前发送SYNACK 包的数量

net.ipv4.tcp_synack_retries = 1

#内核放弃创建链接以前发送SYN 包的数量

net.ipv4.tcp_syn_retries = 1

#启用timewait 快速回收

net.ipv4.tcp_tw_recycle = 1

#开启重用。容许将TIME-WAIT sockets 从新用于新的TCP 链接

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

net.ipv4.tcp_keepalive_time = 30

#容许系统打开的端口范围

net.ipv4.ip_local_port_range = 1024    65000

#修改防火墙表大小，默认65536

#net.netfilter.nf_conntrack_max=655350

#net.netfilter.nf_conntrack_tcp_timeout_established=1200

# 确保无人能修改路由表

net.ipv4.conf.all.accept_redirects = 0

net.ipv4.conf.default.accept_redirects = 0

net.ipv4.conf.all.secure_redirects = 0

net.ipv4.conf.default.secure_redirects = 0

执行sysctl -p使参数生效，永久生效。