Anyway, I guess your problem is that your host keys are not listed on ~/.ssh/known_hosts. You can add them as follows:

my @hosts = qw(foo1.bar.com foo2.bar.com ...);

for (@hosts) {
  system "ssh $_ -o PreferredAuthentications=publickey -o StrictHostKe
+yChecking=no true"
}
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$ssh->login($username,$password); this is the 57th line. If I'm using system "ssh ... " it will work fine. I'm trying to use it through Net:SSH::Perl I dont want to use the shell script inside the perl script.

You only need to run the code I posted before once in order to populate ~/.ssh/known_hosts, after that, your script using Net::SSH::Perl would be able to connect to any host.

update: it seems that Net::SSH::Perl looks for the host keys in ~/.ssh/known_hosts2. I don't know if just copying the entries saved by your system SSH client from ~/.ssh/known_hosts to ~/.ssh/known_hosts2 will work.

Does connecting work from outside of Perl?

This sounds to me more like an issue to take up with your system administrators than with Perl.

yes, I'm able to login to the servers using ssh. Once I use ssh from cmd line the entry will be added in the identity_file and the script is gathering the data for that particular servers. But when it comes to other servers its fails.

From looking through the Net::SSH::Perl documentation, I see no way of adding a host to the known identities. I recommend you get the list of trusted servers and their fingerprints from your system administrators.

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper::Concise;
use Net::SSH::Perl;

my $host = 'host';
my $user = 'user';
my $pass = 'password';


my $ssh = Net::SSH::Perl->new(
          $host, 
          debug => 1,
          protocol => 2,1
);
$ssh->login($user, $pass);
$ssh->session_id;
$ssh->config;
print Dumper $ssh;

exit;
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