#!/usr/bin/perl

use strict;
use warnings;

use Net::FTPSSL;

 open (STDERR, "> logfile.txt");  # Redirects STDERR to this file.

 my %connectionHash = (
     Port                => 21,
     Encryption          => 'E',
     Debug                => 1,
     OverridePASV         => 'xxx.xxx.xxx.xxx',
     Croak                => 0,
     PreserveTimestamp    => 0,
 );

my %sslHash = (
     #SSL_cert_file    => '',
     #SSL_reuse_ctx    => '',
     SSL_key_file    => 'MD5:9f:...f9',
     #SSL_ca_file        => '',
     #SSL_use_cert    => 1,
 );

 $connectionHash{SSL_Client_Certificate} = \%sslHash;

 my $ftps = Net::FTPSSL->new(
         'xxx.xxx.xxx.xxx:',
         %connectionHash,
     );

 $ftps->login ('user', 'pass') or warn "Could not login to xxx.xxx.xxx.xxx: ", $ftps->message;

 $ftps->nlst();
 $ftps->quit();