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

[Otto Moerbeek]

On Mon, Mar 30, 2020 at 08:37:24AM +0200, Otto Moerbeek via dnsdist wrote:

> On Sun, Mar 29, 2020 at 06:20:00PM +0000, Christoph via dnsdist wrote:
> 
> > Hi,
> > 
> > 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:
> > https://dnsdist.org/reference/config.html?highlight=adddohlocal#addDOHLocal
> > 
> > 
> > This is on FreeBSD 12.1 with dnsdist v1.4.0
> > 
> > thanks,
> > Christoph
> > 
> > 
> > refs:
> > 
> > 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.
> > 
> 
> Reading https://www.freebsd.org/doc/en/books/handbook/configtuning-kernel-limits.html
> I would expect that you want to increase kern.ipc.soacceptqueue
> 
> 	-Otto
https://docs.freebsd.org/doc/12.1-RELEASE/usr/local/share/doc/freebsd/en/books/handbook/configtuning-kernel-limits.html

confirms that that is very likely the proper sysctl for your version,

	-Otto