keeping UDP "session" alive when using NAT

[Nathan Stratton Treadway]

On Tue, Oct 23, 2012 at 23:15:31 +0200, Guus Sliepen wrote:
> Which version are you using exactly? Recent versions also send UDP packets at
> the PingInterval, this is part of the PMTUDiscovery feature which is enabled by
> default.

Thanks for the pointer; I didn't pick out that option as being related
to this issue.

Currently both sides of my VPN are fairly old, v1.0.3 on the home side
and 1.0.8 on the office side.  So it seems that both are old enough the
PMTUDiscovery defaults to "off".

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)?

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)?

Thanks again for you help.

						Nathan

 


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