The personal website of Philip Mather

Poor Man's Expect SSO

Posted Sat, 02/06/2010 - 16:20 by philip.mather

The second script is merely for the completeness of this example the primary focus is how to use expect to repeatedly enter a password at an SSH prompt generated by some repeated task being performed via SSH. Obviously using loops and automatic password entry could allow you to break a large number of machines very quickly and encoding your password into a file is a security issue so use at your own risk and with some common sense...

#!/usr/bin/expect -f
# Title: poor_mans_expect_SSO.exp
# Author: Philip Mather
# Version: 0.5
# Notes: Basically just a wrapper script for any other script that uses SSH to repeatedly login to servers.
 
spawn ./interesting_action_over_ssh.sh
set timeout 600
 
expect "*?assword:*" {
   send "MySuperPassword\r"
   exp_continue
}

...and this is an example of the sort of script that iterates over servers doing some task that Expect can handle...

#!/bin/bash
# Title: interesting_action_over_ssh.sh
# Author: Philip Mather
# Version: 0.5
# Notes: Just an example script.
 
server="webserver01
webserver02
webserver03"
 
for i in ${servers}
do
   ssh -o StrictHostKeyChecking=no someluser@${i} "find /etc/ -type f 2> /dev/null | xargs sudo md5sum" > ./results/${i}.md5results
done
 
for i in ${servers}
do
   diff --suppress-common-lines --side-by-side results/webserver01.results results/${i}.results
done