[dnsdist] dnsdist - Bad file descriptor

[Aleš Rygl]

Hi all,

I am facing a bad file descriptor message when preparing our new 
configuration where dnsdist is listening on multiple interfaces. The 
situation is following. dnsdist is running on a sever with three bond 
interfaces. Two of them have two IPv4 and IPv6 address on  them and are 
used for DNS traffic. There is one for the physical interface and the 
second one is a VRRP floating IP, shared between two identical servers.

Sometimes it happens that dnsdist is not responding to queries on IPv6 
when the server is rebooted. They time out. I have noticed this error:

May 22 09:34:33 rzt-lvs2 dnsdist[966]: Marking downstream murena4-ipv6 
([2001:1ae8:2:4010::1:5]:53) as 'up'
May 22 09:34:33 rzt-lvs2 dnsdist[966]: Error connecting to new server 
with address [2001:1ae8:2:4010::1:5]:53: connecting socket to 
[2001:1ae8:2:4010::1:5]:53: Bad file descriptor
May 22 09:34:34 rzt-lvs2 dnsdist[966]: Marking downstream murena4-ipv6 
([2001:1ae8:2:4010::1:5]:53) as 'up'
May 22 09:34:34 rzt-lvs2 dnsdist[966]: Marking downstream murena4-ipv6 
([2001:1ae8:2:4010::1:5]:53) as 'up'
May 22 09:34:34 rzt-lvs2 dnsdist[966]: Error connecting to new server 
with address [2001:1ae8:2:4010::1:5]:53: connecting socket to 
[2001:1ae8:2:4010::1:5]:53: Bad file descriptor
May 22 09:34:34 rzt-lvs2 dnsdist[966]: Error connecting to new server 
with address [2001:1ae8:2:4010::1:5]:53: connecting socket to 
[2001:1ae8:2:4010::1:5]:53: Bad file descriptor
May 22 09:34:35 rzt-lvs2 dnsdist[966]: Marking downstream murena4-ipv6 
([2001:1ae8:2:4010::1:5]:53) as 'up'
May 22 09:34:35 rzt-lvs2 dnsdist[966]: Marking downstream murena4-ipv6 
([2001:1ae8:2:4010::1:5]:53) as 'up'
May 22 09:34:35 rzt-lvs2 dnsdist[966]: Error connecting to new server 
with address [2001:1ae8:2:4010::1:5]:53: connecting socket to 
[2001:1ae8:2:4010::1:5]:53: Bad file descriptor
May 22 09:34:35 rzt-lvs2 dnsdist[966]: Error connecting to new server 
with address [2001:1ae8:2:4010::1:5]:53: connecting socket to 
[2001:1ae8:2:4010::1:5]:53: Bad file descriptor
May 22 09:34:36 rzt-lvs2 dnsdist[966]: Marking downstream murena4-ipv6 
([2001:1ae8:2:4010::1:5]:53) as 'up'

What is wrong here? The resolver above is reachable via one of the bond 
interfaces and is responding (it is a backup from another site). When 
dnsdist is restarted it is ok. dnsdist is 1.3.0

Thanks for help.


BR

Ales