[dnsdist] how to increase connection qlen on DoH listener?

Christoph cm at appliedprivacy.net
Sun Mar 29 18:20:00 UTC 2020


due to log entries saying:
"Listen queue overflow: 193 already in queue awaiting acceptance"
we increased
kern.ipc.somaxconn to 2048

after restarting dnsdist we noticed that while nginx takes
the new setting into account dnsdist remains at 128:

netstat -Lan
Current listen queue sizes (qlen/incqlen/maxqlen)
Proto Listen
tcp4  0/0/128      <<< dnsdist
tcp4  5/0/2048     <<< nginx

Is there a way to tell dnsdist to increase the connection queue on the
DoH listener?

I didn't not see something like that in the documentation:

This is on FreeBSD 12.1 with dnsdist v1.4.0



kern.ipc.somaxconn: Maximum listen socket pending connection accept
queue size

from FreeBSD netstat(1) manual page:
-L      Show the size of the various listen queues.  The first
        count shows the number of unaccepted connections, the
        second count shows the amount of unaccepted incomplete
        connections, and the third count is the maximum number of
        queued connections.

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