use Net::SSL (); # From Crypt-SSLeay
BEGIN {<br />
  $Net::HTTPS::SSL_SOCKET_CLASS = "Net::SSL"; # Force use of Net::SSL
  $ENV{HTTPS_PROXY} = 'http://10.0.3.1:3128';
}

##</code><code>##

require LWP::UserAgent;
 
my $ua = LWP::UserAgent->new(ssl_opts => { verify_hostname => 0});
$ua->agent("Mozilla/8.0");
$ua->timeout(10);

my $req = HTTP::Request->new( GET => "https://sis-t.redsys.es:25443/sis/entradaXMLEntidad/");
$req->header( 'Accept' => 'text/html' );

# send request
my $res = $ua->request($req);

# check the outcome
if ( $res->is_success ) {
    print $res->decoded_content;
} else {
    print "Error: " . $res->status_line . "\n";
}