Subject: bin/17338: TTL in DHCP is too smal
To: None <email@example.com>
From: None <firstname.lastname@example.org>
Date: 06/20/2002 15:36:05
>Synopsis: The TTL for DHCP requests is too smal
>Arrival-Date: Thu Jun 20 13:37:00 PDT 2002
>Originator: Paul Dokas
>Release: NetBSD 1.6B
University of Minnesota
System: NetBSD caligula 1.6B NetBSD 1.6B (CALIGULA) #23: Tue Jun 18 15:04:03 CDT 2002 root@caligula:/big/src/sys/arch/i386/compile/CALIGULA i386
My ISP (AT&T broadband) recently "upgraded" their network. As a result,
my NetBSD based firewall was a whopping 20 hops away from the DHCP server.
The TTL that's hardcoded for the DHCP Request packets is 16. As a result,
I was completely unable to get a DHCP lease from my ISP.
The TTL should probably be bumped up slightly. I'd suggest 32.
Attempt to get a DHCP lease on an AT&T Cable Modem using NetBSD.
The quick and dirty answer is to edit common/packet.c in the ISC DHCP
source. Line 159 currently reads:
ip.ip_ttl = 16;
I changed it to be:
ip.ip_ttl = 32;
Doing this allowed me to reach the DHCP server.
A better answer is to make this be a configurable option. option default-ip-ttl
doesn't do it, although from the man page I would expect that it does.
Any fix that we apply should really be passed back to ISC. I'll probably
file a PR with them regardless.