[nsd-users] Enabling recvmmsg logs errors from sendmmsg call

Anand Buddhdev anandb at ripe.net
Thu Dec 29 16:47:57 UTC 2016

I've built NSD 4.1.14 on CentOS 7 with the --enable-recvmmsg option to
configure. Running with this NSD on a server produces such log entries:

error: sendmmsg [0]=::A.B.C.D count=1 failed: No route to host
error: sendmmsg [0]=::a count=1 failed: No route to host

In the above log lines, A.B.C.D is a real IP address that I have obscured.

I wasn't seeing any such log entries before. They've only appeared after
building NSD with --enable-recvmmsg.

The server has a static default route, so it should always be able to
send DNS responses. If I query the kernel, it says it has a route:

# ip route get A.B.C.D from
A.B.C.D from via E.F.G.H dev em2

E.F.G.H is the static default gateway.

Has anyone else seen such errors? Any idea why NSD is emitting them?


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