如何批量检测端口连通性、端口是否开放（二）

如何批量检测端口连通性、端口是否开放（二）

本站之前有篇用nc来探测端口是否连通的文章，点我查看

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 ~]#

今天我们来介绍一种新的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

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