in reply to
Creating an ARP Packet
If you need to use Perl, you'll probably get farthest by using the module hooks into libpcap, which implements raw socket functionality on *NIX and Windows. (A previous discussion of raw sockets in Perl is here).
Glancing at CPAN, there's NetPacket::ARP, but apparently encoding isn't implemented. Still, it shouldn't be too hard to finish that yourself since the meat of the decoder is in a fairly self-documenting call to unpack, which I imagine could be inverted fairly easily. Once you have the encoded packet, one or more of NetPacket::Ethernet, Net::PcapUtils, and Net::RawIP should help you get it on the wire.