Firewall Wizards mailing list archives
ip classless?
From: "Behm, Jeffrey L." <BehmJL () bvsg com>
Date: Fri, 25 Apr 2003 10:11:22 -0500
I'm wondering, and perhaps this isn't the right forum, but...what are the *security* implications of changing "no ip classless" to "ip classless" in a Cisco Router IOS. The router is the perimeter router, between the DMZ and the Internet. I found http://www.networkking.net/out/IPClassless.php (a humorous, but informative read, thanks Bernard) which, to me, says, if you break a class into pieces, you have to tell the router about every single piece of the class, otherwise the router will simply drop packets to destinations (in that class) you haven't told the router about. However, the article in the above URL deals with RIP, whereas my case only deals with static routing. So, to extrapolate that out to just static routing, do the same rules apply? We are arguing that rather than having to specify how to route all the specific destinations in that class (some inside, but most out to the Internet), that one could just specify static routes (to those destinations we know are on inside) to the inside interface, and enable "ip classless" and let it direct the "other stuff" to the default route, i.e. out to the Internet. We feel more comfortable simply using multiple static routes to get that class routed correctly, so this question is mostly academic at this point. I guess the underlying problem we have is that just because we don't fully understand "ip classless" we feel *more* secure using static routes. The question is, do they accomplish exactly the same thing, or should we be paranoid regarding the "ip classless?" Could someone bounce packets off/through the router by having ip classless enabled, whereas they couldn't if it was disabled? Jeff _______________________________________________ firewall-wizards mailing list firewall-wizards () honor icsalabs com http://honor.icsalabs.com/mailman/listinfo/firewall-wizards
Current thread:
- ip classless? Behm, Jeffrey L. (Apr 25)
- RE: ip classless? Michael (Apr 26)