Ethernet identification

[Paulo Henrique Baptista de Oliveira <baptista@cos.ufrj.br>]

Hello, all,

the people here at the department have bought a software (proprietary) 
usually available for Unix platforms. We've got their Solaris and
Linux version. For the Solaris they asked us the "hostid" to put somewhere in
the code and avoid "piracy". But the Debian GNU/Linux
machines doesn't respond to this command. So they asked us the following:

I will only need the ethernet card number in the following format:

00:00:00 ..... (10 characters)

Have somebody there anu idea on how I get this number by a simple promptline
command?

Thank you in advance,

MPassini