Bugtraq mailing list archives
Broadcast and multi-homed routing condition in TCP/IP stack.
From: Kenny Jansson <kenson () SENTOR SE>
Date: Wed, 7 Mar 2001 16:26:41 +0100
In light of the current discussion about the "Loopback and multi-homed routing flaw in TCP/IP stack." it's worth mentioning another "condition" that exists in some TCP/IP stacks. Some stacks will allow TCP connection to be established to the broadcast address configured on any given interface. FreeBSD has had this behaviour for some time 4.x up until 2001/03/03 17:39:20 PST when a fix was comitted to RELENG_4 OpenBSD also exhibits this behaviour. (Tested on 2.7) Linux and Solaris don't. The reason this condition is worth mention is for the cases when you expect a number of external addresses to be exposed and you apply excplicit filtering on those addresses, and wrongly assume that no other endpoints exists to establish connections to. Obvious fix of course if running FreeBSD is to update your kernel to incorporate the commited fix. Obvious workaround is to always practice safe networking, deny everything, then explicitly allow what should be allowed. /Kenny -- Kenny Jansson kenson () sentor se Sentor AB, Västra Strandg. 7B, 753 11 Uppsala, Sweden phn: +46 (0) 18 65 30 00 | gsm: +46 (0) 70 757 30 01
Current thread:
- Broadcast and multi-homed routing condition in TCP/IP stack. Kenny Jansson (Mar 07)
- Re: Broadcast and multi-homed routing condition in TCP/IP stack. Charles M. Hannum (Mar 07)