with possibly some sadness, probably still very relevant. The best book I have ever owned on TCP/IP was published ~1982....and when I read it last year, not much has changed.
One of the nicer things about Unix is that it tends not to change. There's a lot of inertia to overcome in Unix, which is why Ubuntu made (and continues to make) such a big splash, for being willing to change things quickly (and not always for the better).
