I noticed that you used LWP::Simple. You can take that out. I also noticed that you used $pwd for password---that's confusing because pwd stands for "present working directory", so change that to $pass.

The main problem that I see with your code is that you need to explicitly say that you're behind a proxy. What I would do is set the environmental variable for http_proxy. Here you could do:

export http_proxy=http://proxy.srvr.com:8080/
[download]

Then run your script:

#!/usr/bin/perl

use strict;
use warnings;
use LWP::UserAgent;

my $url  = 'http://www.google.com';
my $user = 'user';
my $pass = 'pass';
my $domain = 'domain';

my $ua = LWP::UserAgent->new();
$ua->env_proxy;
$ua->credentials('proxy.srvr.com:8080', 
                 $domain, $user, $pass);
my $res = $ua->get($url);
print $res->header("Server"), "\n";
[download]