第十周（2020-10-23）

1、编写脚本selinux.sh，实现开启或禁用SELinux功能

#!/bin/bash
echo "########################################"
echo -e "Current status:\n`sestatus`"
echo "########################################"
echo -e "\n"
read -p "Please input enable|disable|permissive|quit to set selinux:" Arg
if [ $Arg == "enable" ] ; then
    setenforce 1
    sed -ri.bak  "s#^SELINUX=.*#SELINUX=enforcing#" /etc/selinux/config &>/dev/null
    echo "Selinux current status is `getenforce`"
    echo "Selinux'config file is set `sed -n "/^SELINUX=/p" /etc/selinux/config`"
    exit
elif [ $Arg == "disable" ] ; then
    setenforce 0
    sed -ri.bak  "s#^SELINUX=.*#SELINUX=disabled#" /etc/selinux/config &>/dev/null
    echo "Selinux current status is `getenforce`,But Disabled's status need to reboot"
    echo "Selinux'config file is set `sed -n "/^SELINUX=/p" /etc/selinux/config`"
    exit
elif [ $Arg == "permissive" ] ; then
    setenforce Permissive
    sed -ri.bak  "s#^SELINUX=.*#SELINUX=Permissive#" /etc/selinux/config &>/dev/null
    echo "Selinux current status is `getenforce`"
    echo "Selinux'config file is set `sed -n "/^SELINUX=/p" /etc/selinux/config`"
    exit
else [ $Arg == "quit" ]
    echo "The shell exit"
    exit
fi

 

2、统计/etc/fstab文件中每个文件系统类型出现的次数

方法一：

[root@centos7 script]# cat /etc/fstab 

#
# /etc/fstab
# Created by anaconda on Mon Aug 31 04:22:36 2020
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=880d392a-a957-4a2d-bd3d-ac27c3dd0ea5 /                       xfs     defaults        0 0
UUID=d2a861a3-f322-42ce-b888-6b54ebec59aa /boot                   xfs     defaults        0 0
UUID=f0a2ac4f-21e0-4b02-a97e-6c616ce051a8 /data                   xfs     defaults        0 0
UUID=f62508ed-244e-4c41-8f4b-383ce6047674 swap                    swap    defaults        0 0
[root@centos7 script]# egrep -v '^#|^$' /etc/fstab |awk '{print $3}'|uniq -c
      3 xfs
      1 swap

方法二：

[root@centos7 script]# grep 'UUID' /etc/fstab |tr -s ' '
UUID=880d392a-a957-4a2d-bd3d-ac27c3dd0ea5 / xfs defaults 0 0
UUID=d2a861a3-f322-42ce-b888-6b54ebec59aa /boot xfs defaults 0 0
UUID=f0a2ac4f-21e0-4b02-a97e-6c616ce051a8 /data xfs defaults 0 0
UUID=f62508ed-244e-4c41-8f4b-383ce6047674 swap swap defaults 0 0
[root@centos7 script]# grep 'UUID' /etc/fstab |tr -s ' '|cut -d' ' -f 3
xfs
xfs
xfs
swap
[root@centos7 script]# grep 'UUID' /etc/fstab |tr -s ' '|cut -d' ' -f 3|uniq -c
      3 xfs
      1 swap
[root@centos7 script]# 

方法三：

[root@centos7 script]# sed -r '/^#|^$/d' /etc/fstab
UUID=880d392a-a957-4a2d-bd3d-ac27c3dd0ea5 /                       xfs     defaults        0 0
UUID=d2a861a3-f322-42ce-b888-6b54ebec59aa /boot                   xfs     defaults        0 0
UUID=f0a2ac4f-21e0-4b02-a97e-6c616ce051a8 /data                   xfs     defaults        0 0
UUID=f62508ed-244e-4c41-8f4b-383ce6047674 swap                    swap    defaults        0 0
[root@centos7 script]# sed -r '/^#|^$/d' /etc/fstab|tr -s ' '|cut -d' ' -f3
xfs
xfs
xfs
swap
[root@centos7 script]# sed -r '/^#|^$/d' /etc/fstab|tr -s ' '|cut -d' ' -f3|uniq -c
      3 xfs
      1 swap

方法四：

[root@centos7 script]# awk '/UUID/' /etc/fstab 
UUID=880d392a-a957-4a2d-bd3d-ac27c3dd0ea5 /                       xfs     defaults        0 0
UUID=d2a861a3-f322-42ce-b888-6b54ebec59aa /boot                   xfs     defaults        0 0
UUID=f0a2ac4f-21e0-4b02-a97e-6c616ce051a8 /data                   xfs     defaults        0 0
UUID=f62508ed-244e-4c41-8f4b-383ce6047674 swap                    swap    defaults        0 0
[root@centos7 script]# awk '/UUID/{print $3}' /etc/fstab 
xfs
xfs
xfs
swap
[root@centos7 script]# awk '/UUID/{print $3}' /etc/fstab |uniq -c
      3 xfs
      1 swap

 

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

[root@centos7 script]# echo "Yd$C@M05MB%9&Bdh7dq+YVixp3vpw" | awk '{gsub(/[^0-9]/,"",$0);print $0}'
05973

 

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

cat /root/access_log  | awk '{IP[$1]++}END{for(i in IP){print i,IP[i]}}'  > /tmp/hosts.txt
while read  ip number;do
if [ $number -gt 100 ] ;then
iptables -A INPUT -s $ip -j REJECT
echo "from $ip  $number rejected" >> /tmp/reject.txt
fi
done < /tmp/hosts.txt