![](https://images2015.cnblogs.com/blog/721057/201612/721057-20161213110448558-1186676837.png)
[root@renjia ~]# echo "yanjin"|passwd --stdin jinyan
visudo
root ALL=(ALL) ALL
renjia ALL=(ALL) NOPASSWD: ALL
leader ALL=(ALL) ALL
server time
1.yum源
2.安装必要的软件包
3.关闭SELINUX
[root@renjia ~]# vim /etc/selinux/config
SELINUX=disabled
[root@renjia ~]# getenforce
Enforcing
[root@renjia ~]# setenforce 0
[root@renjia ~]# getenforce
Permissive
/etc/init.d/iptables stop
[root@renjia ~]# mkdir -p /server/scripts
[root@renjia ~]# cd /server/scripts/
[root@renjia scripts]# vim del.sh
[root@renjia scripts]# ll
总用量 4
-rw-r--r-- 1 root root 50 12月 26 13:12 del.sh
4.runlevel init 0~6
[root@renjia ~]# runlevel
N 3
cat /etc/inittab
setup
ntsysv
刚装完系统时保留服务:
crond
network
sshd
syslog
脚本管理开机自启动的服务:
LANG=en
for jinyan in `chkconfig --list|grep 3:on|awk '{print $1}'`;do chkconfig --level 3 $jinyan off;done
for jinyan in crond network syslog sshd ;do chkconfig --level 3 $jinyan on;done
chkconfig --list|grep 3:on
内核优化
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
#iptables
net.ipv4.ip_conntrack_max = 25000000
net.ipv4.netfilter.ip_conntrack_max=25000000
net.ipv4.netfilter.ip_conntrack_tcp_timeout_established=180
net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait=120
net.ipv4.netfilter.ip_conntrack_tcp_timeout_close_wait=60
net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait=120
sysctl -p
/etc/init.d/iptables start
linux定时任务Crond之服务器同步时间
[root@jinyan ~]# /usr/sbin/ntpdate time.windows.com
26 Dec 12:42:45 ntpdate[2929]: step time server 64.4.10.33 offset -28179.740945 sec
[root@jinyan ~]# date
Thu Dec 26 12:43:04 CST 2013
26 Dec 12:42:45 ntpdate[2929]: step time server 64.4.10.33 offset -28179.740945 sec
[root@jinyan ~]# date
Thu Dec 26 12:43:04 CST 2013
[root@jinyan ~]# /sbin/ntpdate time.windows.com
26 Dec 12:44:34 ntpdate[2934]: adjust time server 65.55.56.206 offset -0.036207 sec
26 Dec 12:44:34 ntpdate[2934]: adjust time server 65.55.56.206 offset -0.036207 sec
crontab -e
#del file
00 00 * * 6 /bin/sh /server/scripts/del.sh >/dev/null 2>&1
#sync sys time by jinyan at 2013-12-26
*/5 * * * * /sbin/ntpdate time.windows.com >/dev/null 2>&1
00 00 * * 6 /bin/sh /server/scripts/del.sh >/dev/null 2>&1
#sync sys time by jinyan at 2013-12-26
*/5 * * * * /sbin/ntpdate time.windows.com >/dev/null 2>&1
crontab -l
#del file
00 00 * * 6 /bin/sh /server/scripts/del.sh >/dev/null 2>&1
#sync sys time by jinyan at 2013-12-26
*/5 * * * * /sbin/ntpdate time.windows.com >/dev/null 2>&1
00 00 * * 6 /bin/sh /server/scripts/del.sh >/dev/null 2>&1
#sync sys time by jinyan at 2013-12-26
*/5 * * * * /sbin/ntpdate time.windows.com >/dev/null 2>&1