[erlang-questions] Intermittent failures connecting C hiddennodes

David Mercer <>
Fri Jul 6 15:37:18 CEST 2007


Richard Andrews wrote:
> It could be a firewall or NAT issue; I've seen stateful firewalls get
confused
> and block connections for a long time.

This indeed has happened to me, and it is quite frustrating and difficult to
detect for application-level software developers like myself.  I am no
network expert by any extent of the imagination, but I have learned a lot
about TCP just because I've had to prove to our network services team that
problems are network issues rather than application.  In a recent case (a
few weeks ago), two separate networks were joined by a firewall, but to me
they appeared as one network, so I was not even aware that there was a
firewall in between.  Anyway, the firewall didn't really like long periods
of inactivity on a TCP connection and would cause errors and then block
future connections for some reason.  I don't know the specifics, I only know
that once one of the network guys figured it out, it magically fixed itself.

David




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