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设置Sysctl.conf用以提高Linux的性能

Sysctl是一个允许您改变正在运行中的Linux系统的接口。它包含一些 TCP/IP 堆栈和虚拟内存系统的高级选项, 这可以让有经验的管理员提高引人注目的系统性能。用sysctl可以读取设置超过五百个系统变量。基于这点,sysctl(8) 提供两个功能:读取和修改系统设置。


查看所有可读变量:


% sysctl -a


读一个指定的变量,例如 kern.maxproc:


% sysctl kern.maxproc kern.maxproc: 1044


要设置一个指定的变量,直接用 variable=value 这样的语法:


# sysctl kern.maxfiles=5000


kern.maxfiles: 2088 -> 5000


您可以使用sysctl修改系统变量,也可以通过编辑sysctl.conf文件来修改系统变量。sysctl.conf 看起来很像 rc.conf。它用 variable=value 的形式来设定值。指定的值在系统进入多用户模式之后被设定。并不是所有的变量都可以在这个模式下设定。


sysctl 变量的设置通常是字符串、数字或者布尔型。 (布尔型用 1 来表示’yes’,用 0 来表示’no’)。


sysctl -w kernel.sysrq=0


sysctl -w kernel.core_uses_pid=1


sysctl -w net.ipv4.conf.default.accept_redirects=0


sysctl -w net.ipv4.conf.default.accept_source_route=0


sysctl -w net.ipv4.conf.default.rp_filter=1


sysctl -w net.ipv4.tcp_syncookies=1


sysctl -w net.ipv4.tcp_max_syn_backlog=2048


sysctl -w net.ipv4.tcp_fin_timeout=30


sysctl -w net.ipv4.tcp_synack_retries=2


sysctl -w net.ipv4.tcp_keepalive_time=3600


sysctl -w net.ipv4.tcp_window_scaling=1


sysctl -w net.ipv4.tcp_sack=1


配置sysctl


编辑此文件:


vi /etc/sysctl.conf


如果该文件为空,则输入以下内容,否则请根据情况自己做调整:


# Controls source route verification


# Default should work for all interfaces


net.ipv4.conf.default.rp_filter = 1


# net.ipv4.conf.all.rp_filter = 1


# net.ipv4.conf.lo.rp_filter = 1


# net.ipv4.conf.eth0.rp_filter = 1


# Disables IP source routing


# Default should work for all interfaces


net.ipv4.conf.default.accept_source_route = 0


# net.ipv4.conf.all.accept_source_route = 0


# net.ipv4.conf.lo.accept_source_route = 0


# net.ipv4.conf.eth0.accept_source_route = 0


# Controls the System Request debugging functionality of the kernel


kernel.sysrq = 0


# Controls whether core dumps will append the PID to the core filename.


# Useful for debugging multi-threaded applications.


kernel.core_uses_pid = 1


# Increase maximum amount of memory allocated to shm


# Only uncomment if needed!


# kernel.shmmax = 67108864


# Disable ICMP Redirect Acceptance


# Default should work for all interfaces


net.ipv4.conf.default.accept_redirects = 0


# net.ipv4.conf.all.accept_redirects = 0


# net.ipv4.conf.lo.accept_redirects = 0


# net.ipv4.conf.eth0.accept_redirects = 0


# Enable Log Spoofed Packets, Source Routed Packets, Redirect Packets


# Default should work for all interfaces


net.ipv4.conf.default.log_martians = 1


# net.ipv4.conf.all.log_martians = 1


# net.ipv4.conf.lo.log_martians = 1


# net.ipv4.conf.eth0.log_martians = 1


# Decrease the time default value for tcp_fin_timeout connection


net.ipv4.tcp_fin_timeout = 25


# Decrease the time default value for tcp_keepalive_time connection


net.ipv4.tcp_keepalive_time = 1200


# Turn on the tcp_window_scaling


net.ipv4.tcp_window_scaling = 1


# Turn on the tcp_sack


net.ipv4.tcp_sack = 1


# tcp_fack should be on because of sack


net.ipv4.tcp_fack = 1


# Turn on the tcp_timestamps


net.ipv4.tcp_timestamps = 1


# Enable TCP SYN Cookie Protection


net.ipv4.tcp_syncookies = 1


# Enable ignoring broadcasts request


net.ipv4.icmp_echo_ignore_broadcasts = 1


# Enable bad error message Protection


net.ipv4.icmp_ignore_bogus_error_responses = 1


# Make more local ports available


# net.ipv4.ip_local_port_range = 1024 65000


# Set TCP Re-Ordering value in kernel to ‘5′


net.ipv4.tcp_reordering = 5


# Lower syn retry rates


net.ipv4.tcp_synack_retries = 2


net.ipv4.tcp_syn_retries = 3


# Set Max SYN Backlog to ‘2048′


net.ipv4.tcp_max_syn_backlog = 2048


# Various Settings


net.core.netdev_max_backlog = 1024


# Increase the maximum number of skb-heads to be cached


net.core.hot_list_length = 256


# Increase the tcp-time-wait buckets pool size


net.ipv4.tcp_max_tw_buckets = 360000


# This will increase the amount of memory available for socket input/output queues


net.core.rmem_default = 65535


net.core.rmem_max = 8388608


net.ipv4.tcp_rmem = 4096 87380 8388608


net.core.wmem_default = 65535


net.core.wmem_max = 8388608


net.ipv4.tcp_wmem = 4096 65535 8388608


net.ipv4.tcp_mem = 8388608 8388608 8388608


net.core.optmem_max = 40960


如果希望屏蔽别人 ping 你的主机,则加入以下代码:


# Disable ping requests


net.ipv4.icmp_echo_ignore_all = 1


编辑完成后,请执行以下命令使变动立即生效:


/sbin/sysctl -p


/sbin/sysctl -w net.ipv4.route.flush=1

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