使用shell检查443端口

脚本如下：
[root@lzw oldboy]# more check_443.sh 
#!/bin/bash
#check_443_port
#2019-8-27
PORT=443
count=0
for i in $(cat ip_list.dat)
   do 
    ((count++))
   echo "count=$count"
  ( sleep 1;) | telnet $i $PORT >>telnet_result.txt
   done
cat telnet_result.txt | grep -B 1 \] | grep [0-9] | awk '{print $3}' | cut -d '.' -f 1,2,3,4 >> telnet_alive.txt
cat ip_list.dat telnet_alive.txt | sort | uniq -u >>telnet_die.txt

检查IP地址列表：
[root@lzw oldboy]# more ip_list.dat 
220.178.124.93
220.178.124.94
220.178.124.132
220.178.124.133

运行脚本：
[root@lzw oldboy]# sh check_443.sh 
count=1
Connection closed by foreign host.
count=2
telnet: connect to address 220.178.124.94: Connection refused
count=3
Connection closed by foreign host.
count=4
telnet: connect to address 220.178.124.133: Connection refused

查看脚本运行结果：
[root@lzw oldboy]# more telnet_result.txt 
Trying 220.178.124.93...
Connected to 220.178.124.93.
Escape character is '^]'.
Trying 220.178.124.94...
Trying 220.178.124.132...
Connected to 220.178.124.132.
Escape character is '^]'.
Trying 220.178.124.133...

查看开通443端口的地址：
[root@lzw oldboy]# more telnet_alive.txt 
220.178.124.93
220.178.124.132

查看未开通443端口的地址：
[root@lzw oldboy]# more telnet_die.txt 
220.178.124.133
220.178.124.94

注释：本案例首先要检查是否安装Telnet包，Linux系统默认没有安装。本脚本主要定义本次要探测IP端口，通过for循环依次读取ip_list.dat文件中每行的IP地址，当读取第一行的IP地址220.178.124.93时，Telnet220.178.124.93地址是否开通443端口，检查结果写入telnet_result.txt文件。依次类推，读取完ip_list.dat文件中IP地址跳出循环，生成最终的telnet_result.txt文件。
    接下来，只是对telnet_result.txt文本的编辑。可以通过分开执行命令理解脚本的含义：
    
1)过滤出符号 ] 之前的一行：
[root@lzw oldboy]# cat telnet_result.txt | grep -B 1 \]
Connected to 220.178.124.93.
Escape character is '^]'.
--
Connected to 220.178.124.132.
Escape character is '^]'.

2)过滤出包含数字的0-9行：
[root@lzw oldboy]# cat telnet_result.txt | grep -B 1 \] | grep [0-9] 
Connected to 220.178.124.93.
Connected to 220.178.124.132.
3）输出第三个域的字符串，每个域以空格隔开。
[root@lzw oldboy]# cat telnet_result.txt | grep -B 1 \] | grep [0-9] | awk '{print $3}'
220.178.124.93.
220.178.124.132.
4）剪切符号.之前的数字
[root@lzw oldboy]# cat telnet_result.txt | grep -B 1 \] | grep [0-9] | awk '{print $3}' | cut -d '.' -f 1,2,3,4 
220.178.124.93
220.178.124.132
5）对比ip_list.dat telnet_alive.txt 文件内容，列出不同的内容放到telnet_die.txt文件。