hey Halftux, hmm.. i don't know very much about trademarks so I really can't advise you on this. However I think you would be really unlucky if a exterior wall company was to make legal trouble for you over your ip table/firewall application.. but stranger things have happened I guess I think it's different if you were trying to pretend you were that company, or somehow you were using their company name for the benefit of your application. That's not the issue in this case, ofcourse, your application has nothing to do with exterior walling So I'd leave it up to you to decide how to proceed. Depending on how popular Genwall the company is, it might be beneficial to give your application a slightly different name to help your users search for it/find it on search engines etc.

But honestly I don't know what I'm talking about, so maybe someone else with legal knowlege can advise here