Expecting Cisco

Beatnik on 2006-07-10T20:09:21

Accessing the Cisco shell with Expect turned out to be not as difficult as it seemed (so far).

#!/usr/bin/perl

use Expect;
use strict;
my $device = $ARGV[0];
my $password = $ARGV[1];
my $enable_password = $ARGV[2];
my $timeout = 10;
my $command = Expect->spawn("telnet $device");
$command->log_stdout(0);
$command->expect($timeout, -re => "Password:") or die("Failed to get password prompt");
print $command "$password\r";
print $command "enable\r";
$command->expect($timeout, -re => "assword") or die("Did not get a password prompt\n");
print $command "$enable_password\r";
print $command "show log\r";
my $redo = 1;
while($redo)
{ $command->clear_accum();
  $command->expect(1,
               [ qr/More/ => sub { my $comand = shift; print $command "\r"; exp_continue; } ],
               [ qr/#/ => sub { my $exp = shift; $redo = 0; exp_continue; } ],
              );
}
print $command "exit\r";
$command->soft_close();

No luck getting SSH working... since I don't have any SSH based Ciscos at hand.

---

SSH on embedded hosts

grinder on 2006-07-11T18:52:07

If Cisco is anything like Juniper/Netscreen (and in my experience it is :) I wouldn't bother trying to use Perl's own Net::SSH modules. Someone somewhere plays fast and loose with the specs, and I was never able to get the connection to work.

But using Expect to drive a telnet or ssh session to a Juniper box works very well. I spoke to btrott at the time (this was about 5 years ago) he said that he didn't have time to maintain Net::SSH as best it deserved any more.

Re:SSH on embedded hosts

Beatnik on 2006-07-11T19:31:14

SSH on Juniper works fine! Telnet on Cisco works pretty straightforward using Net::Telnet::Cisco. Net::SSH::Perl works if I patch it and only if I stick to 1 call. (enable + show running-config = 2 :( ) Expect seemed the only solution for me. See my previous post on this.