linux优化

第一步：
连上克隆连接的
> /etc/udev/rules.d/70-persistent-net.rules
sed -ri '/HWADDR|UUID/d' /etc/sysconfig/network-scripts/ifcfg-eth*

第二步：
域名解析
cp /etc/hosts{,.bak}

cat >/etc/hosts<<EOF
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
EOF

#所有服务器模板机的基本优化
#0、更改yum源
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup &&
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
mv /etc/yum.repos.d/epel.repo /etc/yum.repos.d/epel.repo.backup
mv /etc/yum.repos.d/epel-testing.repo /etc/yum.repos.d/epel-testing.repo.backup
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo

#yum makecache

#1、关闭selinux
sed -i.bak 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config
grep SELINUX=disabled /etc/selinux/config
setenforce 0
getenforce
#2、关闭iptables
/etc/init.d/iptables stop
/etc/init.d/iptables stop
chkconfig iptables off
#3、精简开机自启动服务
export LANG=en
chkconfig|egrep -v "crond|sshd|network|rsyslog|sysstat"|awk '{print "chkconfig",$1,"off"}'|bash

chkconfig --list|grep 3:on
#4、提权username可以sudo
useradd username
echo 123456|passwd --stdin username
cp /etc/sudoers /etc/sudoers.ori
echo "username ALL=(ALL) NOPASSWD: ALL " >>/etc/sudoers
tail -1 /etc/sudoers
visudo -c
#5、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>>/var/spool/cron/root
echo '*/5 * * * * /usr/sbin/ntpdate pool.ntp.org >/dev/null 2>&1' >>/var/spool/cron/root
crontab -l
#7、命令行安全（可不设置）
#echo 'export TMOUT=300' >>/etc/profile
#echo 'export HISTSIZE=5' >>/etc/profile
#echo 'export HISTFILESIZE=5' >>/etc/profile
#tail -3 /etc/profile
#. /etc/profile
#8、加大文件描述
echo '* - nofile 65535 ' >>/etc/security/limits.conf
tail -1 /etc/security/limits.conf
#9、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
#10、安装其他小软件
yum install lrzsz nmap tree dos2unix nc telnet -y

#11、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