linux shell 检查端口开放

傷城~ 2021-08-28 21:50 387阅读 0赞

端口探测无非也就是telnet、nc的命令，用法基本如下：

[root@SY-68-2 ~]#echo "bye" | timeout 3 telnet www.baidu.com 81
    Trying 61.135.169.121...
    [root@SY-68-2 ~]#echo "bye" | timeout 3 telnet www.baidu.com 80
    Trying 61.135.169.125...
    Connected to www.baidu.com.
    Escape character is '^]'.
    Connection closed by foreign host.
    [root@SY-68-2 ~]#
    [root@SY-33-2 ~]# nc -z -w 5 www.baidu.com 80 && echo OK || echo Failed
    Connection to www.baidu.com 80 port [tcp/http] succeeded!
    OK
    [root@SY-68-2 ~]# nc -z -w 5 www.baidu.com 81 && echo OK || echo Failed
    Failed
    [root@SY-68-2 ~]#

bash自身包含的一种方式：  
/dev/tcp/host/port 和 /dev/udp/host/port

用法也很简单：

[root@SY-68-2 ~]# echo >/dev/tcp/www.baidu.com/80 && echo "port 80 is open" || echo "port 80 is closed"
    port 80 is open
    [root@SY-68-2 ~]#

但这种用法本身是不带超时时间设置的，幸好我们有timeout命令，组合起来便是：

[root@SY-68-2 ~]#timeout 5 bash -c "echo >/dev/tcp/www.baidu.com/80" > /dev/null 2>&1 && echo "port 80 is open" || echo "port 80 is closed"
    port 80 is open
    [root@SY-68-2 ~]#
    [root@SY-68-2 ~]#timeout 5 bash -c "echo >/dev/tcp/www.baidu.com/8080" > /dev/null 2>&1 && echo "port 8080 is open" || echo "port 8080 is closed"
    port 8080 is closed
    [root@SY-68-2 ~]#

就是如此，写一个for循环，便可以批量检测了。

样例文件如下：

#cat ports
    119.181.69.96 8080
    220.181.111.188 80
    119.181.20.18 8080
    202.108.22.220 53

脚本和输出结果如下：

cat ports | while read line
    do
    
    IP=`echo $line |awk '{print $1}'`
      PORT=`echo $line |awk '{print $2}'`
    
    timeout 5 bash -c "echo >/dev/tcp/$IP/$PORT" > /dev/null 2>&1 && echo "$IP $PORT is open" || echo "$IP $PORT is closed"
    
    done
    
    # sh test.sh
    119.181.69.96 8080 is closed
    220.181.111.188 80 is open
    119.181.20.18 8080 is closed
    202.108.22.220 53 is open