Bug#757876: freeciv-client-gtk: can't start a local game

[Marko Lindqvist]

On 12 August 2014 20:05, Jacob Nevins
<jacobn+debian at chiark.greenend.org.uk> wrote:
> Xavier Cartron writes:
>> - If I do 'freeciv-server -p 5557',, the server starts normally.
>
> Enh. Of course the client might not be choosing 5557. It tries to find a
> free port and tells the server to use that.
> (Sure would have been useful if we (upstream) had thought to log the
> port we were attempting to use, either in the client or in the
> server...)
>
> If the client had, for instance, a logical bug where it searched for the
> first *used* port, or its test for free-ness always returned false
> causing the port to wrap around, I guess that could cause this symptom.
> (The relevant code is in utility/netintf.c:find_next_free_port().)
>
> Is there anything unusual about your network stack? Lack of IP
> connectivity, real IPv6 connectivity, non-default kernel options,
> anything like that?

 My guess would be that this is related to IPv4/IPv6 dual stack. Could
it be so that the same port number is free in IPv4, but bound in IPv6?
There might be a bug in initial detection of the free port in that it
checks only IPv4, but then final bind wants them both (for security
reasons among others)
 The other explanation coming to my mind is that it's the detection of
the free port itself that somehow fails to free the port back after
succesfully binding it.


 - ML