#!/bin/bash

#set env

export LANG="en_US.UTF-8"

export PATH=$PATH:/bin/sbin:/usr/sbin

#whether root to running user

if [[ $(whoami) != root ]];then

   echo "please su - root run the script."

fi

SERVICE=`which service`

CHKCONFIG=`which chkconfig`

. /etc/init.d/functions

#install packages

installTmout(){

   echo "TMOUT 180" >> /etc/profile\

   [ $? -eq 0 ] && action "TMOUT is ok" /bin/true || exit 1

}

installTool(){

   yum -y install sysstat ntp net-snmp lrzsz rsync > /dev/vull 2>&1

   [ $? -eq 0 ] && action "Tools is ok" /bin/true || exit 1

}

#update the system lang

initI18n(){

   cat /etc/sysconfig/i18n > /etc/sysconfig/i18n.bak

   echo "LANG="en_US.UTF-8"" >> /etc/sysconfig/i18n

   source /etc/sysconfig/i18n

   [ $? -eq 0 ] && action "LANG is ok" /bin/true || exit 1

   sleep 1

}

#start iptables

initIptables(){

   cat /etc/selinux/config > /etc/selinux/config.bak

   setenforce 0

   /etc/init.d/iptables start > /dev/null 2 >& 1

   [ $? -eq 0 ] && action "Iptables is ok" /bin/true || exit 1

   sleep 1

}

#close not need to service

initService(){

   export LANG="en_US.UTF-8"

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

   for i in crond network rsyslog sshd;do chkconfig --level 3 $i on;done

   [ $? -eq 0 ] && action "Service is ok" /bin/true || exit 1

   sleep 1

}

#youhua for ssh

initSsh(){

   cat /etc/ssh/sshd_config > /etc/ssh/sshd_config.bak

   sed -i ‘s/#Port 22/Port 22022/‘ /etc/ssh/sshd_config

   sed -i ‘s/#PermitRootLogin yes/PermitRootLogin yes/‘ /etc/ssh/sshd_config

   sed -i ‘s/#PermitEmptyPasswords no/PermitEmptyPasswords no/‘ /etc/ssh/sshd_config

   sed -i ‘s/#UseDNS yes/UseDNS no/‘ /etc/ssh/sshd_config

   /etc/init.d/sshd restart > /dev/null 2 >& 1

   [ $? -eq 0 ] && action "Ssh is ok" /bin/true || exit 1

}

#sync time

syncSystemTime(){

   ping www.baidu.com -c 1 > /dev/null 2 >& 1

   if [ $? -eq 0 -a `grep pool.ntp.org /var/spool/cron/root | grep -v grep | wc -l` -lt 1 ]; then

      echo "*/5 * * * * /usr/sbin/ntpdate time.windows.com > /dev/null 2>&1" >> /var/spool/cron/root

 [ $? -eq 0 ] && action "SystemTime is ok" /bin/true || exit 1

   fi

}

#change file inode

openFiles(){

   cat /etc/security/limits.conf > /etc/security/limits.conf.bak

   echo "ulimit -HSn 65535" >> /etc/security/limits.conf

   sysctl -p 

   [ $? -eq 0 ] && action "limit is ok" /bin/true || exi 1

   sleep 1

}

#youhua kernel

openKernel(){

   cat /etc/sysctl.conf > /etc/sysctl.conf.bak

   cat >> /etc/sysctl.conf << EOF

    net.ipv4.tcp_tw_reuse = 1  

net.ipv4.tcp_tw_recycle = 1  

net.ipv4.ip_local_port_range = 102465000  

net.ipv4.tcp_max_syn_backlog = 8192  

net.ipv4.tcp_max_tw_buckets = 5000  

net.ipv4.tcp_mem = 192000 300000 732000

net.ipv4.tcp_rmem = 51200 131072 204800

net.ipv4.tcp_wmem = 51200 131072 204800

net.ipv4.tcp_orphan_retries = 3

net.ipv4.tcp_syn_retries = 3

net.ipv4.tcp_synack_retries = 3

net.ipv4.tcp_retries2 = 5

net.ipv4.tcp_fin_timeout = 30

net.ipv4.tcp_max_orphans = 2000

net.ipv4.tcp_syncookies = 1

net.ipv4.tcp_tw_reuse = 1

net.ipv4.tcp_tw_recycle = 1

net.ipv4.tcp_keepalive_time = 20

net.ipv4.tcp_keepalive_intvl = 5

net.ipv4.tcp_keepalive_probes = 2

vm.dirty_expire_centisecs = 1500

vm.dirty_writeback_centisecs = 1000

vm.dirty_ratio = 20

vm.dirty_background_ratio = 100

vm.min_free_kbytes=409600

vm.vfs_cache_pressure=200

vm.swappiness = 40

   EOF

   /sbin/sysctl -p && action "kernel is ok" /bin/true || action "kernel is faile" /bin/false

   sleep 1

}

#init_snmp

init_snmp(){

   cat /etc/snmp/snmpd.conf > /etc/snmp/snmpd.conf.bak

   sed -i ‘s/#view all/view all/‘ /etc/snmp/snmpd.conf

   sed -i ‘s/#access MyROGroup/access MyROGroup/‘ /etc/snmp/snmpd.conf

   ${CHKCONFIG} snmpd on

   ${SERVICE} snmpd start

   [ $? -eq 0 ] && action "snmpd is starting" /bin/true \

   || action "snmpd is faile" /bin/false

}

installTool

initI18n

initSelinux

initService

initSsh

syncSystemTime

openFiles

openKernel

init_snmp

本文出自 “三人行，必有我师焉” 博客，请务必保留此出处http://lovers.blog.51cto.com/5850489/1576281

优化系统脚本（简写）