use LWP::UserAgent;
my $ua = new LWP::UserAgent;
$ua->proxy(['http']=> 'http://11.12.5.20:3350');

my $url = 'http://www.yahoo.com';

my $req = HTTP::Request->new(GET => $url);
$req->proxy_authorization_basic($username, $password);
my $res = $ua->request($req);

if ($res->is_success) {
	print $res->content;
}