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How to Telnet via BASH Script

by | Feb 25, 2015 | RHEL / CentOS

This article will show you how to Telnet via BASH script and return the status as open or close. This has been tested on CentOS/RedHat and hopefully should work on all other Linux distributions as well.

Create a file telnet_script.sh. This script is to Telnet SSH port i.e. 22

# vi telnet_script.sh
#!/bin/bash
echo "172.16.66.200 22" | \
while read host port; do
  r=$(bash -c 'exec 3<> /dev/tcp/'$host'/'$port';echo $?' 2>/dev/null)
  if [ "$r" = "0" ]; then
    echo $host $port is open
  else
    echo $host $port is closed
  fi
done

 Output:

telnet script 1

This is when Telnet for SSH Port responds OK.

Output:

telnet script 2

This is when Telnet for SSH Port responds FAIL.

If you encounter any errors during the process, let us know via Contact Us and will try our best to help.

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