Sorry b10m, but bengmau is looking for the MAC of a remote system on his domain. According to CPAN, Net::Address::Ethernet only finds the MAC of the local machine.

Unfortunately bengmau, I don't have an answer strictly in perl for you yet, I just didn't want you to get frustrated with this module. Abigail-II's solution below works great if there's already an entry in your arp table. You might want to ping the ip just before you do the arp -a on it... Oh yeah, and make sure that either arp is in your path or address it explicitly.