I took your sample and experimented with it.

#!/usr/bin/perl

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

my $mac = 'http://www.perlmonks.org/?node_id=848086';

eval {
    do {
        my $request    = HTTP::Request->new( GET => $mac );
        my $ua         = LWP::UserAgent->new;
        $ua->timeout(30);
        $ua->env_proxy;
        my $response = $ua->request($request);
        if ( $response->is_success ) {
            print $response->decoded_content;
        }
        else {
            print $response->status_line, "\n";
        }
    };
}
[download]

Update: I took out $SIG{ALRM}. It didn't work and seemed unnecessary. Added print to status_line and timeout. "status_line' works better.