linux系统优化

1、更改yum源
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo
EPEL (Extra Packages for Enterprise Linux)拓展yum源
2、关闭selinux
3、关闭iptables
4、精简开机自启动服务
chkconfig|egrep -v “crond|sshd|network|rsyslog|sysstat”|awk ‘{print “chkconfig”,$1,“off”}’|bash
chkconfig --list|grep 3:on
5、设置英文字符集
cp /etc/sysconfig/i18n /etc/sysconfig/i18n.ori
echo ‘LANG=“en_US.UTF-8”’ >/etc/sysconfig/i18n
source /etc/sysconfig/i18n
echo $LANG
6、时间同步
echo ‘#time sync by lidao at 2017-03-08’ >>/var/spool/cron/root
echo '/5 * * * * /usr/sbin/ntpdate pool.ntp.org >/dev/null 2>&1’ >>/var/spool/cron/root
crontab -l
7、加大文件描述
echo ’ - nofile 65535 ’ >>/etc/security/limits.conf
tail -1 /etc/security/limits.conf
8、内核优化
cat >>/etc/sysctl.conf<<EOF
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
#以下参数是对iptables防火墙的优化，防火墙不开会提示，可以忽略不理。
net.nf_conntrack_max = 25000000
net.netfilter.nf_conntrack_max = 25000000
net.netfilter.nf_conntrack_tcp_timeout_established = 180
net.netfilter.nf_conntrack_tcp_timeout_time_wait = 120
net.netfilter.nf_conntrack_tcp_timeout_close_wait = 60
net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 120
EOF
sysctl -p
9、ssh连接速度慢优化
sed -i.bak ‘s@#UseDNS yes@UseDNS no@g;s@^GSSAPIAuthentication yes@GSSAPIAuthentication no@g’ /etc/ssh/sshd_config
/etc/init.d/sshd reload