Le vendredi 01 août 2014 à 16:31 +0200, Bastien Durel a écrit : > Hello, > > I face a strange problem with my IPv6 connection. (one of them, actually) > > I got an OpenBSD router I use to connect to 2 ISPs and various internal > networks. > > One of my link cannot use IPv6 from some time (as it's my backup link, I > can't say exactly when it failed). This provider have native IPv6. > > here is the connected interface: > sis1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > lladdr 00:00:24:cf:42:ad > description: WAN2 > priority: 0 > groups: egress > media: Ethernet autoselect (100baseTX full-duplex) > status: active > inet 192.168.1.1 netmask 0xffffff00 broadcast 192.168.1.255 > inet6 fe80::200:24ff:fecf:42ad%sis1 prefixlen 64 scopeid 0x2 > inet6 2001:41d0:fc8d:f200::1 prefixlen 64 > > When I try to ping the "outside world", I can see the packet leaving via > sis1 (tcpdump -i sis1 -nvv -s 1500 ip6) > > 15:58:41.703964 2001:41d0:fc8d:f200::1 > 2001:41d0:8:91a::1: icmp6: echo > request (id:65fd seq:9) [icmp6 cksum ok] (len 16, hlim 64) > > (the "outside world" recieves it, and awnser) > Then the provider's router sends a nsol to my router > > 15:58:41.751487 fe80::5a98:35ff:fe1c:af06 > ff02::1:ff00:1: icmp6: > neighbor sol: who has 2001:41d0:fc8d:f200::1(src lladdr: > 58:98:35:1c:af:06) [icmp6 cksum ok] (len 32, hlim 255) > > it responds > > 15:58:41.751588 fe80::200:24ff:fecf:42ad > fe80::5a98:35ff:fe1c:af06: > icmp6: neighbor adv: tgt is 2001:41d0:fc8d:f200::1(RSO)(tgt lladdr: > 00:00:24:cf:42:ad) [bad icmp6 cksum 8c3a!] (len 32, hlim 255) > > then nothing happens. > > I had the same problem when the ISP's modem is put in bridge mode, > except the router that sens the sollicitation is a CISCO ... > > Is there something I can have miss in my side ? I see there's a "bad > checksum", could this be a problem ? > > Here is my dmesg: (from syslog) [...] > > Thanks, > I put a laptop on the other side of the cable to get a trace from the router point of view, then this is the trace : https://owncloud.geekwu.org/public.php?service=files&t=2399a4db476667fdc4d5ed68422e5edc
We can see the echo request going through the interface, then the laptop sends a Nsol, the OpenBSD box responds with Nadv, and nothing happens. The Icmp6 checksum of the Nadv is zero, other packets comming from the BSD box have correct checksums: I guess it's the problem ? The laptop answers to ping from times to time; when the BSD box emits a Nsol to get laptop's address. The Nsol have a correct checksum. Looks like a bug, no ? Regards, -- Bastien Durel <bast...@geekwu.org>
