linux运维、架构之路-linux基础优化

1、查看linux版本

cat /etc/redhat-release 
#CentOS release 6.9 (Final) ————>查看版本号
uname -m
#x86_64                     ————>查看系统64位/32位
uname -r
#2.6.32-696.el6.x86_64      ——————>内核版本

2、关闭selinux和iptables

sed -i 's#=enforcing#=disabled#g' /etc/selinux/config
setenforce 0 #——————>临时关闭
getenforce

/etc/init.d/iptables stop
chkconfig iptables off

3、更改字符集，支持中文，但不建议最好用英文字符集，防止乱码问题

echo $LANG
en_US.UTF-8             #——————>查看系统字符集是否正确

LANG=en
export LANG=en_US.utf8  #—————>临时生效解决中文乱码
echo "LANG=en_US.utf8" >/etc/sysconfig/i18n #——————>永久生效
source /etc/sysconfig/i18n                  #——————>立即让配置文件生效

4、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

5、时间同步

echo '#time sync by yanxinjiang at 2017-01-01' >>/var/spool/cron/root
echo '*/5 * * * * /usr/sbin/ntpdate  pool.ntp.org >/dev/null 2>&1' >>/var/spool/cron/root
crontab -l

6、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

7、加大文件描述符

echo '*               -       nofile          65535 ' >>/etc/security/limits.conf

8、linux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

10、常用小工具安装

yum install lrzsz nmap tree dos2unix nc telnet -y

11、通过sudo提权普通用户管理

useradd oldboy
echo 123456|passwd --stdin oldboy
cp /etc/sudoers /etc/sudoers.ori
echo "oldboy  ALL=(ALL) NOPASSWD: ALL " >>/etc/sudoers
tail -1 /etc/sudoers
visudo -c