my $ssh = Net::OpenSSH($host,
                       master_opts => [-o => 'ProxyCommand=ssh foo nc %h %p']);

##</code><code>##

my $ssh = Net::OpenSSH->new($host,
                            gateway => { proxies => ['ssh://intermediate_host',
                                                     'ssh://another_host',
                                                     'http://proxy:8080'] } );