Maintained by: NLnet Labs

error: outgoing tcp: bind: Address already in use

Nick Urbanik
Tue Jul 25 08:43:00 CEST 2017

On 24/07/17 12:57 +0200, W.C.A. Wijngaards via Unbound-users wrote:
>On 21/07/17 05:29, Nick Urbanik via Unbound-users wrote:
>> On 06/07/17 18:13 +1000, Nick Urbanik via Unbound-users wrote:
>>> A DNS server running unbound 1.6.3 has these messages; any suggestions
>>> on what is happening?
>>> error: serviced_tcp_initiate: failed to send tcp query
>>> error: outgoing tcp: bind: Address already in use
>> Could our setting of
>> max-udp-size: 3072
>> be too low?  Any guidelines for tuning this?
>I think unbound 1.6.4 port reuse option may solve it for you as Quirin

I will use 1.6.4 as soon as permitted :-)

>The max-udp-size is not important for this error you are
>seeing in logs.

But if the reply will not fit in 3072 bytes, then will unbound not
then need to use TCP?  And if there are a very large number of
responses required, could that not cause the TCP ports to run out if
they cannot easily be reused?

This problem arises on our resolvers, which are separate from the
caches; the caches forward to the resolvers.
Nick Urbanik 808-71011 nick.urbanik at
GPG: 7FFA CDC7 5A77 0558 DC7A 790A 16DF EC5B BB9D 2C24  ID: BB9D2C24
I disclaim, therefore I am.