马哥教育N48-第十周作业

1. 编写脚本selinux.sh，实现开启或禁用SELINUX功能。
脚本如下：

关闭selinux
[root@centos7 scripts37]#bash -x selinux.sh

• read -p ‘please input character set selinux for {start|stop} :’ SE
  please input character set selinux for {start|stop} :stop
  ++ sed -rn ‘s@^SELINUX=(.*)@\1@p’ /etc/selinux/config
• SEC=enforcing
• ‘[’ stop == start ‘]’
• ‘[’ stop == stop ‘]’
• ‘[’ enforcing == disabled ‘]’
• ‘[’ enforcing == enforcing ‘]’
• sed -ri ‘s@^SELINUX=(.*)@SELINUX=disabled@’ /etc/selinux/config
• echo ‘selinux stop succeed’
  selinux stop succeed
  开启selinux
  [root@centos7 scripts37]#bash -x selinux.sh
• read -p ‘please input character set selinux for {start|stop} :’ SE
  please input character set selinux for {start|stop} :start
  ++ sed -rn ‘s@^SELINUX=(.*)@\1@p’ /etc/selinux/config
• SEC=disabled
• ‘[’ start == start ‘]’
• ‘[’ disabled == enforcing ‘]’
• ‘[’ disabled == disabled ‘]’
• sed -ri ‘s@^SELINUX=(.*)@SELINUX=enforcing@’ /etc/selinux/config
• echo ‘selinux start succeed’
  selinux start succeed
  2、统计/etc/fstab文件中每个文件系统类型出现的次数
  grep “^UUID” /etc/fstab | awk -F" " ‘{print $3}’ | uniq -c

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

echo “Yd$C@M05MB%9&Bdh7dq+YVixp3vpw” | awk ‘{gsub(/[^0-9]/,"",$0);print $0}’

4、解决DOS攻击生产案例:根据web日志或者或者网络连接数，监控当某个IP 并发连接数或者短时内PV达到100，即调用防火墙命令封掉对应的IP，监控频 率每隔5分钟。防火墙命令为:iptables -A INPUT -s IP -j REJECT

将脚本存到计划任务中，设置定时任务计划：

[root@centos7 ~]# crontab -e
*/5 * * * * /root/checkip.sh