keeping UDP "session" alive when using NAT

[Guus Sliepen]

On Tue, Oct 23, 2012 at 06:27:09PM -0400, Nathan Stratton Treadway wrote:

> Can you explain how PMTUDiscovery relates to the PingInterval?  From the
> description of the PMTUDiscovery option in the man page and manual, I
> got the impression that the MTU would be discovered once as the
> connection came up.... are you saying that it's actually re-discovered
> each PingInterval?  Or instead that as part of implementing the
> PMTUDiscovery function you had to implement a "NOP" packet on the data
> connection, and thus after that point you had Tinc send the NOP packet
> on both connections every PingInterval seconds (at least in some
> situations)?

At first the PMTUDiscovery method tries to determine the exact path MTU, but
afterwards it sends a few packets every PingInterval to check whether the path
still works. So this should also keep your NAT mappings alive. 

> In any case, do you think it would help my situation for me to turn on
> PMTUDiscovery in my config file (given the above-listed versions)?

I don't know, those versions are pretty old, I would have to dig in the
changelogs to see if they also send the periodic packets. You should consider
upgrading!

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <guus at tinc-vpn.org>
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