10、Linux練習腳本

1、編寫腳本selinux.sh，實現開啓或禁用SELinux功能

[root@C76 ~]# cat selinux.sh 
#!/bin/bash
 read -p "please input character set selinux for {start|stop} :" s
 se=$(sed -rn 's@^SELINUX=(.*)@\1@'p /etc/selinux/config)
 if [ $s == 'start' ];then
         if [ $se == 'enforcing' ];then
                 echo "selinux  status is enforcing"
         elif [ $se == 'disabled' ];then
                 sed -ri 's@^SELINUX=(.*)@SELINUX=enforcing@' /etc/selinux/config && echo "selinux is start "
         fi
 elif [ $s == 'stop' ];then
        if [ $se == 'disabled' ];then
                echo "selinux  status is disabled"
        elif [ $se == 'enforcing' ];then
                sed -ri 's@^SELINUX=(.*)@SELINUX=disabled@' /etc/selinux/config && echo "selinux is stop"
        fi
fi

2、統計/etc/fstab文件中每個文件系統類型出現的次數

[root@C76 ~]# cat /etc/fstab|grep "^/" |awk  '{print $3}'|uniq -c

3、提取出字符串Yd$C@M05MB%9&Bdh7dq+YVixp3vpw中的所有數字

1、[root@C76 ~]#  echo 'Yd$C@M05MB%9&Bdh7dq+YVixp3vpw' > ll.txt
2、[root@C76 ~]# cat ll.txt |grep -o [0-9]

結果：

4、解決DOS攻擊生產案例:根據web日誌或者或者網絡連接數，監控當某個IP 併發連接數或者短時內PV達到100，即調用防火牆命令封掉對應的IP，監控頻 率每隔5分鐘。防火牆命令爲:iptables -A INPUT -s IP -j REJECT

[root@C76 ~]# ss -ntpl| awk '{print $4}'|awk -F: '{print $1}'|grep ^[0-9]|uniq -c|sort -nr >/data/ss.log
[root@C76 ~]# cat fire.sh 
#!/bin/bash
while read  ip n;do
if [ $n -gt 100 ] ;then
iptables -A INPUT -s $ip -j REJECT
echo "from $ip  $n rejecti" >> /tmp/reject.txt
fi
done < /data/ss.log