sed -i 's#SELINUX=enforcing#SELINUX=disabled#' /etc/selinux/config
grep SELINUX=disabled /etc/selinux/config
setenforce 0
getenforce
/etc/init.d/iptables stop
/etc/init.d/iptables stop
chkconfig iptables off
chkconfig|egrep -v "crond|sshd|network|rsyslog|sysstat"|awk '{print "chkconfig",$1,"off"}'|bash
useradd oldboy
\cp /etc/sudoers /etc/sudoers.bak
echo "oldboy ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
tail -l /etc/sudoers
visudo -c
echo '#time sync by 20has at 2017-5-9' >>/var/spool/cron/root
echo '*/5 * * * * /usr/sbin/ntpdate time.nist.gov >/dev/null 2>&1' >>/var/spool/cron/root
crontab -l
echo 'export TMOUT=3000' >> /etc/profile
echo 'export HISTSIZE=5' >> /etc/profile
echo 'export HISTFILESIZE=5' >> /etc/profile
tail -3 /etc/profile
. /etc/profile
echo '* - nofile 65535' >> /etc/security/limits.conf
tail -l /etc/security/limits.conf
#about selinux
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.netdv_max_backlog = 16384
net.ipv4.tcp_max_orphans = 16384
#以下參數是對iptables防火牆的優化，防火牆不開會提示，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
#yumrepo
cp /etc/yum.repos.d/CentOS-Base.repo{,.backup}
yum -y install wget
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
#yum clean all #清理緩存
#yum makecache #建立本地緩存
#mv /etc/yum.repos.d/epel.repo{,.backup}
#mv /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 -y install lrzsz nmap tree dos2unix nc
yum groupinstall -y "Base" "Compatibility libraries" "Debugging Tools" "Development tools" #安裝基礎軟件（特別是針對最小化安裝centos）