CentOS優化筆記

CentOS優化筆記

設置固定IP

vi /etc/sysconfig/network-scripts/ifcfg-eth0
ONBOOT=yes
BOOTPROTO=none
DNS1=202.96.209.133
IPADDR=192.168.159.68
PREFIX=24
GATEWAY=192.168.159.2

修改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

同步時間

yum install ntpdate
#修改時區立即生效
cp /usr/share/zoneinfo/UTC /etc/localtime
#cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
#修改時間
date -s "12/24/16 18:05:00"
hwclock -w
#hwclock -s （--hctosys）
#查看時間
date
date "+%Y-%m-%d %H:%M:%S"
#UTC時間
date -u
hwclock
#同步時間
ntpdate time.nist.gov
crontab -e
*/5 * * * * /usr/sbin/ntpdate time.nist.gov >/dev/null 2>&1

關閉selinux和iptables

#臨時生效
getenforce
setenforce 0
service iptables stop
#永久生效
vi /etc/selinux/config
SELINUX=disabled
chkconfig iptables off
chkconfig --list iptables

修改文件描述符數量

ulimit -n
ulimit -HSn 65535
vi /etc/security/limits.conf
*               -       nofile          65535

中文字符集

vi /etc/sysconfig/i18n
LANG="en_US.UTF-8"
#LANG="zh_CN.UTF-8"
source /etc/sysconfig/i18n
>/etc/issue

內核參數優化

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
sysctl -p

精簡自啟服務

for ser in `chkconfig --list | grep "3:on"|awk '{print $1}'`; do chkconfig $ser off; done
for ser in crond network sshd rsyslog ;do chkconfig $ser on; done

使用普通用戶

useradd naitcn
passwd naitcn
visudo
naitcn  ALL=(ALL)       NOPASSWD: ALL
sudo su -

強化SSH配置

cp /etc/ssh/sshd_config /etc/ssh/sshd_config.ori
vi /etc/ssh/sshd_config
Port 55522
PermitEmptyPasswords no
#PermitRootLogin no
GSSAPIAuthentication no
UseDNS no
service sshd restart

鎖定提權文件

chattr +i /etc/passwd /etc/shadow /etc/group /etc/gshadow /etc/inittab 
lsattr /etc/passwd
mv /usr/bin/chattr /opt/hello