Linux系统优化

[root@renjia ~]# echo "yanjin"|passwd --stdin jinyan

visudo

root    ALL=(ALL)       ALL

renjia  ALL=(ALL)       NOPASSWD: ALL

leader    ALL=(ALL)       ALL

server time

1.yum源

2.安装必要的软件包

3.关闭SELINUX

[root@renjia ~]# vim /etc/selinux/config 

SELINUX=disabled

[root@renjia ~]# getenforce  

Enforcing

[root@renjia ~]# setenforce 0

[root@renjia ~]# getenforce  

Permissive

/etc/init.d/iptables stop

[root@renjia ~]# mkdir -p /server/scripts

[root@renjia ~]# cd /server/scripts/

[root@renjia scripts]# vim del.sh

[root@renjia scripts]# ll

总用量 4

-rw-r--r-- 1 root root 50 12月 26 13:12 del.sh

4.runlevel init 0~6

[root@renjia ~]# runlevel 

N 3

cat /etc/inittab

setup

ntsysv

刚装完系统时保留服务：

crond

network

sshd

syslog

脚本管理开机自启动的服务：

LANG=en

for jinyan in `chkconfig --list|grep 3:on|awk '{print $1}'`;do chkconfig --level 3 $jinyan off;done

for jinyan in crond network syslog sshd ;do chkconfig --level 3 $jinyan on;done

chkconfig --list|grep 3:on

内核优化

vi /etc/sysctl.conf

net.ipv4.tcp_fin_timeout = 2

net.ipv4.tcp_tw_reuse = 1

net.ipv4.tcp_tw_recycle = 1

net.ipv4.tcp_syncookies = 1

net.ipv4.tcp_keepalive_time = 600

net.ipv4.ip_local_port_range = 4000          65000

net.ipv4.tcp_max_syn_backlog = 16384

net.ipv4.tcp_max_tw_buckets = 36000

net.ipv4.route.gc_timeout = 100

net.ipv4.tcp_syn_retries = 1

net.ipv4.tcp_synack_retries = 1

net.core.somaxconn = 16384

net.core.netdev_max_backlog = 16384

net.ipv4.tcp_max_orphans = 16384

#iptables

net.ipv4.ip_conntrack_max = 25000000

net.ipv4.netfilter.ip_conntrack_max=25000000

net.ipv4.netfilter.ip_conntrack_tcp_timeout_established=180

net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait=120

net.ipv4.netfilter.ip_conntrack_tcp_timeout_close_wait=60

net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait=120

sysctl -p

/etc/init.d/iptables start

linux定时任务Crond之服务器同步时间

[root@jinyan ~]# /usr/sbin/ntpdate time.windows.com
26 Dec 12:42:45 ntpdate[2929]: step time server 64.4.10.33 offset -28179.740945 sec
[root@jinyan ~]# date
Thu Dec 26 12:43:04 CST 2013

[root@jinyan ~]# /sbin/ntpdate time.windows.com
26 Dec 12:44:34 ntpdate[2934]: adjust time server 65.55.56.206 offset -0.036207 sec

crontab -e

#del file
00 00 * * 6 /bin/sh /server/scripts/del.sh >/dev/null 2>&1
#sync sys time by jinyan at 2013-12-26
*/5 * * * * /sbin/ntpdate time.windows.com >/dev/null 2>&1

crontab -l

#del file
00 00 * * 6 /bin/sh /server/scripts/del.sh >/dev/null 2>&1
#sync sys time by jinyan at 2013-12-26
*/5 * * * * /sbin/ntpdate time.windows.com >/dev/null 2>&1

来自为知笔记(Wiz)