[Systems] IPv6 broken on build slaves (bender) again

[Sascha Silbe]

Excerpts from Sascha Silbe's message of Thu Sep 16 23:06:43 +0200 2010:

> IPv6 is broken for the build slaves on bender again. strace shows radvd
> sends advertisements, but tcpdump doesn't show them.

I'm stuck with this. For testing I've inserted an ip6tables rule to
accept everything. I've also fixed the link-local address on virbr0
(there was a mismatch between the MAC address and the link-local
address). Still no change and nothing useful in the logs.

tcpdump shows that the VMs send packets on virbr0 and strace shows radvd
sends packets on virbr0, but neither do the packets from the VMs arrive
at radvd (strace) nor do the packets from radvd arrive on virbr0
(tcpdump).

Any idea what could be dropping the packets?

This is the output of strace:

bender:~# strace -f -e trace=network radvd -u radvd -d 5 -m stderr
[Sep 17 14:04:18] radvd: version 1.6 started
socket(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6) = 3
setsockopt(3, SOL_IPV6, 0x31 /* IPV6_??? */, [1], 4) = 0
setsockopt(3, SOL_RAW, 0x7 /* RAW_??? */, [2], 4) = 0
setsockopt(3, SOL_IPV6, IPV6_UNICAST_HOPS, [255], 4) = 0
setsockopt(3, SOL_IPV6, IPV6_MULTICAST_HOPS, [255], 4) = 0
setsockopt(3, SOL_IPV6, 0x33 /* IPV6_??? */, [1], 4) = 0
setsockopt(3, SOL_ICMPV6, 1, "\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\237\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377", 32) = 0
socket(PF_FILE, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 4
connect(4, {sa_family=AF_FILE, path="/var/run/nscd/socket"}, 110) = 0
sendto(4, "\2\0\0\0\v\0\0\0\7\0\0\0passwd\0", 19, MSG_NOSIGNAL, NULL, 0) = 19
recvmsg(4, {msg_name(0)=NULL, msg_iov(2)=[{"passwd\0", 7}, {"\270O\3\0\0\0\0\0", 8}], msg_controllen=24, {cmsg_len=20, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, {5}}, msg_flags=MSG_CMSG_CLOEXEC}, MSG_CMSG_CLOEXEC) = 15
[Sep 17 14:04:18] radvd: mtu for virbr0 is 1500
[Sep 17 14:04:18] radvd: hardware type for virbr0 is 1
[Sep 17 14:04:18] radvd: link layer token length for virbr0 is 48
[Sep 17 14:04:18] radvd: prefix length for virbr0 is 64
setsockopt(3, SOL_IPV6, IPV6_ADD_MEMBERSHIP, "\377\2\0\0\0\0\0\0\0\0\0\0\0\0\0\2\7\0\0\0", 20) = 0
[Sep 17 14:04:18] radvd: interface definition for virbr0 is ok
[Sep 17 14:04:18] radvd: Initializing privsep
Process 2535 attached
[pid  2534] socket(PF_FILE, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 4
[pid  2534] connect(4, {sa_family=AF_FILE, path="/var/run/nscd/socket"}, 110) = 0
[pid  2534] sendto(4, "\2\0\0\0\f\0\0\0\6\0\0\0group\0", 18, MSG_NOSIGNAL, NULL, 0) = 18
[pid  2534] recvmsg(4, {msg_name(0)=NULL, msg_iov(2)=[{"group\0", 6}, {"\270O\3\0\0\0\0\0", 8}], msg_controllen=24, {cmsg_len=20, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, {6}}, msg_flags=MSG_CMSG_CLOEXEC}, MSG_CMSG_CLOEXEC) = 14
[Sep 17 14:04:18] radvd: sending RA on virbr0
[pid  2534] sendmsg(3, {msg_name(28)={sa_family=AF_INET6, sin6_port=htons(58), inet_pton(AF_INET6, "ff02::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=if_nametoindex("virbr0")}, msg_iov(1)=[{"\206\0\0\0@\30\1,\0\0\0\0\0\0\0\0\3\4@\300\0\1Q\200\0\0008@\0\0\0\0"..., 56}], msg_controllen=40, {cmsg_len=36, cmsg_level=SOL_IPV6, cmsg_type=, ...}, msg_flags=0}, 0) = 56
[Sep 17 14:04:18] radvd: setting timer: 16.00 secs
[Sep 17 14:04:18] radvd: setting timer: 16 secs 0 usecs
[Sep 17 14:04:18] radvd: calling schedule_timer from set_timer context
[Sep 17 14:04:18] radvd: calling alarm: 15 secs, 999915 usecs

Sascha
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