i'm currently editing an upcoming book on linux firewalls which recommends -- if one needs some TCP/IP background -- the stevens book "TCP/IP Illustrated, Volume 1: The Protocols": http://www.kohala.com/start/tcpipiv1.html which, while a superb book, is now 20 years old. are there any more recent books that have that quality? then again, it's entirely possible that even after 20 years, it's still the best thing out there. recoms for really good TCP/IP tutorial web sites also welcome. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================