Question

我正在尝试编写一个shell脚本，它将IP地址和端口号作为输入，并输出端口是否在主机上打开。我的shell脚本看起来像这样

#!/bin/bash

name=$(echo exit | telnet $1 $2 | grep "Connected")

if [ "$name" == "" ]
then
    echo "Port $2 is not open on $1"
else
    echo "Port $2 is open on $1"
fi

它工作正常，但我的输出包含2行，如下所示：

[root@ip-172-31-8-36 Scripts]# ./test.sh 172.31.35.246 7199
Connection closed by foreign host.
Port 7199 is open on 172.31.35.246

OR

[root@ip-172-31-8-36 Scripts]# ./test.sh 172.31.35.246 7200
telnet: connect to address 172.31.35.246: Connection refused
Port 7200 is not open on 172.31.35.246

我想在两种情况下都抑制输出的第一行。知道怎么做吗？

Answer 1

将telnet的错误输出直接发送到/dev/null：

name=$(echo exit | telnet $1 $2 2>/dev/null | grep "Connected")

Answer 2

穷人的nmap纯粹的狂欢：

host="127.0.0.1"
for port in {1..1024}
do
    echo "" > /dev/tcp/$host/$port && echo "Port $port is open"
done 2>/dev/null

Answer 3

如何使用netcat呢？

$ nc -v -z <host> <port> Connection to <host> <port> port [tcp/https] succeeded!

telnet来确定开放端口（shell脚本）

3 个答案: