Date: Mon, 19 Oct 2009 11:56:34 -0400 From: David Horn <dhorn2000@gmail.com> To: Doug Barton <dougb@freebsd.org> Cc: freebsd-net@freebsd.org, Brooks Davis <brooks@freebsd.org> Subject: Re: Wacky DHCP values that work in windows but not in FreeBSD Message-ID: <25ff90d60910190856t6d0df42cn7e75fc14046220d9@mail.gmail.com> In-Reply-To: <4ADBFA55.9060601@FreeBSD.org> References: <4AD3ABD0.7010603@FreeBSD.org> <25ff90d60910122030r1f8511e9ued9535024fa3078a@mail.gmail.com> <4AD410CB.2060105@FreeBSD.org> <25ff90d60910122255j5ccae96ar7c58488209768956@mail.gmail.com> <4ADBFA55.9060601@FreeBSD.org>
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On Mon, Oct 19, 2009 at 1:34 AM, Doug Barton <dougb@freebsd.org> wrote: > I'm adding Brooks to the cc list since he is mr. dhcp lately. :) > > David Horn wrote: >> On Tue, Oct 13, 2009 at 1:31 AM, Doug Barton <dougb@freebsd.org> wrote: >>> David Horn wrote: >>>> Without seeing the actual tcpdump of the dhcp packets, I would guess >>>> that this is the Classless Static Route option in DHCPv4 (option 121). >>> Ok, I will give the tcpdump option a go as soon as I have a chance. > > I finally had a chance to look at this again (with your revised > tcpdump command line from another mail of yours) and I think you're > right. The log (http://people.freebsd.org/~dougb/tcpdump.log) > definitely mentions Classless-Static-Route. This was with the stock > dhclient in -current. I also tried ISC's 4.1.1b3 just to be sure, and > that did not work either. > According to the tcpdump, the client does specify that it supports option 121 in the request, but the server does not in the reply, so my guess was inaccurate. > I also tried the various incarnations of route that were suggested on > this thread, including all 4 combinations with/without -iface and > -hopcount, and none of that worked either. > > Quick recap, I got the following from dhcp: > Your-IP 76.244.161.xxx > Subnet-Mask Option 1, length 4: 255.255.0.0 > Default-Gateway Option 3, length 4: 151.164.184.xxx > > Now what DID work was something I tried on a whim. Actually two things > worked, 'route add default 76.244.161.1' and (after rebooting) 'route > add default 76.244.0.1'. With either of those I could reach things > both inside the network (like the name server) and out in the wide world. > > I have no idea WHY those worked, I suspect that Mike Smith was right > and there is some sort of proxy-arp going on, but I'm far from a > networking expert. > > I'll leave the tcpdump log up for a while if y'all think it's useful. > I can also test patches for this if someone comes up with a fix. > > > Doug > > >>> Meanwhile, if this is in fact the case how would we make it work in >>> FreeBSD? Is there a newer version of DHCP that handles this properly? >> >> I thought that dhclient originated from ISC, but looking at the >> 4.1.1b2 ISC DHCP source and at the OpenBSD dhclient, I did not see >> option 121 handling in dhclient. =A0The freebsd copy of both dhclient.c, >> and /sbin/dhclient-script there is code for handling this option. =A0 I >> guess the FreeBSD version split from the ISC version at some point, >> and option 121 handling was added (2+ years ago). >> >> As far as fixing/debugging, it all depends on the exact dhcp options >> and values. =A0It might just be a tweak to /sbin/dhclient-script, or it >> may be more complicated. >> >> http://www.freebsd.org/cgi/cvsweb.cgi/src/sbin/dhclient/dhclient.c >> Revision 1.21: download - view: text, markup, annotated - select for dif= fs >> Fri Feb 9 17:50:26 2007 UTC (2 years, 8 months ago) by emaste >> Branches: MAIN >> CVS tags: RELENG_7_BP, RELENG_7_0_BP, RELENG_7_0_0_RELEASE, RELENG_7_0 >> Branch point for: RELENG_7 >> Diff to: previous 1.20: preferred, colored >> Changes since revision 1.20: +68 -0 lines >> >> Implement RFC3442, the Classless Static Route option. >> >> The original DHCP specification includes a route option but it supports >> only class-based routes. =A0RFC3442 adds support for specifying the netm= ask >> width for each static route. =A0A variable length encoding is used to mi= nimize >> the size of this option. >> >> PR: =A0 =A0 =A0 =A0 =A0 =A0 bin/99534 >> Submitted by: =A0 Andrey V. Elsukov <bu7cher@yandex.ru> >> Reviewed by: =A0 =A0brooks >> >> ---Dave H >> > > > -- > > =A0 =A0 =A0 =A0Improve the effectiveness of your Internet presence with > =A0 =A0 =A0 =A0a domain name makeover! =A0 =A0http://SupersetSolutions.co= m/ > >
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