Creating a script for a Telnet session?

scripting telnet
TrentCoder picture TrentCoder · Apr 2, 2009 · Viewed 139.7k times · Source

Does anyone know of an easy way to create a script that can connect to a telnet server, do some usual telnet stuff, and then log off? I am dealing with users who are not familiar with telnet and the commands they will need to run. All I want is for them to double-click on a script, and have that script automatically execute the commands for them.

You're probably wondering, "What platform are the users on?" They will be on both Windows and Linux. Implementations in languages like Perl, Java, or Python are acceptable. I see that Perl has a Net:: Telnet module. Has anyone used that?

My ideal solution would be to create two script files. a BAT file for windows, and a shell script for Linux. While this would make dual maintenance an issue, it would mean I wouldn't have to install Perl/Java/Python/etc... on every machine. Unfortunately, I have not seen any way to automate a telnet session with batch files or shell scripts.

Thanks.

Answer

Vatine picture Vatine · Apr 2, 2009

I've used various methods for scripting telnet sessions under unix, but the simplest one is probably a sequence of echo and sleep commands, with their output piped into telnet. Piping the output into another command is also a possibility.

Silly example

(echo password; echo "show ip route"; sleep 1; echo "quit" ) | telnet myrouter

This (basicallly) retrieves the routing table of a Cisco router.

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