Security Incidents mailing list archives
Re: Private networks and home.{net|com}
From: raane () WMDATA COM (Rasmus Andersson)
Date: Wed, 9 Feb 2000 11:49:06 +0100
"Sachs, Marcus" wrote:
An older router running an older IOS that doesn't know about RFC1918, that is passing internal "non-routable" IPs? ms
Please note that nothing of the following rant is directed at you personally: That is a completely irrelevant guess. RFC 1918 networks are not "non-routable". It's just that you don't route them to/on the Internet. No router treats that nets in any special way apart from that you should _configure_ them not to exchange route information about that nets through your perimeter routers. It's perfectly legal (and in many ways good) to use those addresses on link networks, and filtering out ALL traffic from such addresses is a therefore a Bad Idea(tm). In particular, you MUST let ICMP Unreachable - Fragmentation Needed through to not damage path-MTU discovery. IMHO you should let any ICMP Unreachables through as well as Time Exceeded. There seems to be a growing problem that people are filtering any ICMP and any RFC-1918 addresses without having enough knowledge on the implications. Regards -- Rasmus Andersson WM-data Security http://www.wmdata.se/security Löjtnantsgatan 25, Box 27307, 102 54 Stockholm Tel: +46-(0)8-459 10 46, +46-(0)70-535 14 21 Fax: +46-(0)8-459 10 45 raane () wmdata com PGP Id:70650262
Current thread:
- Re: Private networks and home.{net|com} Sachs, Marcus (Feb 08)
- Re: Private networks and home.{net|com} Rasmus Andersson (Feb 09)
- Re: Private networks and home.{net|com} Pavel Kankovsky (Feb 10)
- <Possible follow-ups>
- Re: Private networks and home.{net|com} Andersson, Rasmus (Feb 08)
- Re: Private networks and home.{net|com} Marc Slemko (Feb 09)
- Re: Private networks and home.{net|com} Sachs, Marcus (Feb 09)
- Re: Private networks and home.{net|com} Rasmus Andersson (Feb 10)
- Re: Private networks and home.{net|com} Jeffrey Papen (Feb 10)
- Re: Private networks and home.{net|com} Jeffrey Papen (Feb 10)
- Re: Private networks and home.{net|com} Rasmus Andersson (Feb 09)