I don't see why it would as long as you both agree to it.I think it might be a good idea for both of you to put it in writing,because it wouldn't be unheard of if one of you screwed the other ones box up,and you don't want your friend to get pissed and say you didn't have permission and call cops or your ISP.If you do decide to call the ISP or somone else about any possible regulations reguarding this,I'd advise you to call it penetration testing or something like that instead of war games,because they might look down on that terminology.