Date: Fri, 21 Aug 2009 16:52:07 -0700 From: Doug Hardie <bc979@lafn.org> To: David Horn <dhorn2000@gmail.com> Cc: FreeBSD Questions <questions@freebsd.org> Subject: Re: Possible bug with IPv6 ICMPv6 handling Message-ID: <93A37662-11AC-4F6D-AFE8-7460A91666FF@lafn.org> In-Reply-To: <25ff90d60908211133s74261676m6333151addf743f@mail.gmail.com> References: <69165A28-4E22-4D6D-B21E-1BD4A3025B0A@lafn.org> <25ff90d60908211133s74261676m6333151addf743f@mail.gmail.com>
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On 21 August 2009, at 11:33, David Horn wrote: > On Fri, Aug 21, 2009 at 1:55 AM, Doug Hardie<bc979@lafn.org> wrote: >> I have found what to me seems like a bug with ICMPv6 handling in >> IPv6. >> However, before submitting a PR I wanted to check to be sure that >> its not a >> misunderstanding on my part. >> >> The network setup. A host (A) connected to a router (B) connected to >> another host (C) on a separate network. When all are up and >> running, A can >> ping6 to C and gets a response. If you power off C and then do the >> ping >> again, tpcdump on A shows an ICMPv6 destination unreachable datagram >> received from B. However ping6 does not report that back to the >> user. A >> ktrace of ping6 shows that it does not receive the ICMPv6 >> response. Its my >> understanding that it should and the ping6 code seems to imply that >> also. Is >> this a bug? >> _______________________________________________ > > What version of FreeBSD are you using ? 7.2 and 7.0. > Did you try the -v parameter to ping6 to display non-echo responses ? > (man ping6) No - didn't notice that in either the ping or ping6 man pages before. > > In a similar test I ran, I was able to get the icmp6 host unreachable > message from ping6 -v on my FreeBSD 7.2 box. (I pinged a non-existent > address/machine off an upstream router) > > uname -a > FreeBSD dhorn-bsd 7.2-RELEASE-p2 FreeBSD 7.2-RELEASE-p2 #0: Wed Jun 24 > 00:57:44 UTC 2009 > root@i386-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC i386 > > dhorn@dhorn-bsd:~> ping6 -v 2001:470:7:584::3 > PING6(56=40+8+8 bytes) 2001:470:8:584:20e:cff:xxxx:xxxx --> > 2001:470:7:584::3 > 64 bytes from 2001:470:7:584::1: Destination Host Unreachable > Vr TC Flow Plen Nxt Hlim > 6 00 00000 0010 3a 3e > 2001:470:8:584:20e:cff:xxxx:xxxx->2001:470:7:584::3 > ICMP6: type = 128, code = 0 > > The other thing to potentially look at would be firewall rules, but > that is unlikely if you can see the icmp6 response in tcpdump. No firewall involved. > > Good Luck. It would appear that this is an error, but in ping and not ping6. Both of their man pages have exactly the same comment for -v. However, ping does show things like Host down etc without the -v argument. Ping6 works per the man page and does not. I don't think that this is worth a PR though. Thanks for the help. > > --Dave >
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