Date: Fri, 11 Jul 2014 02:45:03 +0100 From: Ben Morrow <ben@morrow.me.uk> To: galu@packetdam.com, freebsd-stable@freebsd.org Subject: Re: Weird ISR accounting in 10-STABLE Message-ID: <20140711014459.GA79102@anubis.morrow.me.uk> In-Reply-To: <CABN%2B6JmjMZihF5t7PM149W7Z=PMn4X1yG4ah=R5fo3aQLYpckg@mail.gmail.com> References: <CABN%2B6JmYP4U1vT7r7vy810TUzdH%2BqG=zuHRnNU9fDzOF0J-skg@mail.gmail.com> <201407091402.23537.jhb@freebsd.org> <CABN%2B6JnpiV0JZ0BdNAKv4FOsVJHCZUC6fmDi2-Wwox5EUhrseg@mail.gmail.com> <201407101430.52616.jhb@freebsd.org> <CABN%2B6J=eazu=Xn7v52PBP0SdqU2_VC=jGvWLVy1TrktX=ztgXw@mail.gmail.com>
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Quoth Vlad Galu <galu@packetdam.com>: > On Thu, Jul 10, 2014 at 9:56 PM, Vlad Galu <galu@packetdam.com> wrote: > > > > Good catch, why didn't I think of that earlier! I can see a lot of IPv6 > > traffic that I can't really explain. Since I was running pf with synproxy I > > disabled pf altogether, but that did not improve things. Here is a snapshot > > (source IP address edited): > > > > -- cut here -- > > 22:52:40.195950 IP6 A:B:C:D:E::1000.62571 > ::10.31.31.153.12132: Flags The second address here is an 'IPv4-compatible IPv6 address', which are not these days considered to be useful. See RFC 4291 section 2.5.5.1. I suspect the process which owns A:B:C:D:E::1000.62571 is playing silly games of some sort; possibly it's making Linux-based assumptions about the behaviour of dual-stack hosts which don't apply on BSD. > It was a routing loop! I kept seeing lots of identical SYN packets. I > somehow ended up with this v6 table entry: > -- cut here -- > Routing tables > > Internet6: > > Destination Gateway Flags > Netif Expire > > ::/96 ::1 UGRS > lo0 This is a correct route, and will not cause a routing loop. It's also *not* the same as the IPv6 loopback route (as someone else said); that route looks like ::1 link#2 UH lo0 and should also be present (the link number might be different, obviously). The 'R' flag means 'reject': because these addresses are not useful, there should be a routing table entry to ensure packets addressed to them get thrown away rather than sent out on the wire. You need to find out why they are being generated in the first place. Ben
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