Date: Tue, 8 Jun 2010 14:49:20 -0400 From: "Peter C. Lai" <peter@simons-rock.edu> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: Stephen Clark <sclark46@earthlink.net>, FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: FreeBSD eats 169.254.x.x addressed packets Message-ID: <20100608184919.GY63749@cesium.hyperfine.info> In-Reply-To: <20100608184429.GA12052@icarus.home.lan> References: <4C0E81D7.8020209@earthlink.net> <20100608180506.GA9340@icarus.home.lan> <4C0E8B42.70603@earthlink.net> <20100608184429.GA12052@icarus.home.lan>
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On 2010-06-08 11:44:29AM -0700, Jeremy Chadwick wrote: > On Tue, Jun 08, 2010 at 02:26:10PM -0400, Stephen Clark wrote: > > On 06/08/2010 02:05 PM, Jeremy Chadwick wrote: > > >On Tue, Jun 08, 2010 at 01:45:59PM -0400, Stephen Clark wrote: > > >>Why does FreeBSD 6.3 eat 169.254.x.x addressed packet when > > >>4.9 didn't? > > > > > >The following output would help: > > > > > >- ifconfig -a > > >- netstat -rn > > >- Contents of /etc/rc.conf > > > > > >Also, be aware that RELENG_6 is to be EOL'd at the end of this year: > > >http://security.freebsd.org/ > > > > > Hi Jeremy, > > > > I am not sure that information is relevant. We have two systems configured > > identically one using 4.9 the other 6.3. > > My concern was that someone had botched something up in rc.conf or > during the OS upgrade/migration, resulting in there being no loopback > interface. I also wanted to verify that your routing table looked > correct for what ifconfig showed. > > Other users pointed you to RFC 3927. Wikipedia has this to say: > > http://en.wikipedia.org/wiki/Link-local_address > > "Based on RFC 3927, IPv4 uses the 169.254.0.0/16 range of addresses. > However, the first and last /24 subnet (256 addresses each) in this > block have been excluded from use and are reserved by the standard.[1]" > > I read this to mean 169.254.0.0/24 and 169.254.255.0/24. > > Your previous ifconfig statement shows: > > > $ ifconfig rl0 > > rl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > > options=8<VLAN_MTU> > > inet 192.168.129.1 netmask 0xffffff00 broadcast 192.168.129.255 > > inet 169.254.1.1 netmask 0xffff0000 broadcast 169.254.255.255 > > ether 00:30:18:ae:7c:77 > > media: Ethernet autoselect (100baseTX <full-duplex>) > > status: active > > With this configuration, you're using both the first and last /24 > netblocks -- 169.254.0.0 for your network address, and 169.254.255.255 > for your broadcast address. > > You should be able to avoid this by using 169.254.1.0/24. > RFC 3927 also has complicated rules involving when one can or should not use a link-local address on the same interface as a routable IP, so at best your configuration may not be supported anyway. One should not use a link-local address as if it were under RFC 1918 rules, in particular because link-local involves self-assigned addresses and internal conflict mitigation. -- =========================================================== Peter C. Lai | Bard College at Simon's Rock Systems Administrator | 84 Alford Rd. Information Technology Svcs. | Gt. Barrington, MA 01230 USA peter AT simons-rock.edu | (413) 528-7428 ===========================================================
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