[Mono-list] Listen on same port ipv4 and ipv6

[J Decker]

(First let me vent a little and say I LOVE all the consistency in
network libraries; in MS.NET closing a IPV6 TcpClient sets Client to
null, whereas IPV4 TcpCLient only disposes the object)

I found this old message with no responses..

http://lists.ximian.com/pipermail/mono-list/2014-May/050905.html

I want to listen at the same port address at 0.0.0.0 and :: (ipv4 and
6 address respectively)

in C I would open two listeners.  But I think maybe the .NET runtime
is pre-checking if that port is already used in some internal list of
sockets before attemping to open it in reality.

in C# I will have to do the same thing, since connecting to the v6
address with only the v4 listener at 0.0.0.0 listening fails to
connect and times out.

On Windows I have to, and it works; but again with Mono on Linux it
doesn't work.