[OpenAFS-devel] nat mode

[Jim Rees]

I've imported some code from Disconnected afs that helps with firewalls and
nats.  It introduces a new fs command (and pioctl), "fs discon nat|full".
In nat mode, all servers are checked once a minute, which tends to keep
firewall and nat translations refreshed.

There is more to this that I will try to import later if people like it.
The other important piece is reducing the mtu to 576 in nat mode.  Other
parts include tossing callbacks and rx connections just before a
disconnection.

For the pioctl I just grabbed the next one.  Do we have any process for
coordinating with IBM or arla on pioctls?

Diff is here, comments welcome:

http://www.citi.umich.edu/u/rees/nat.diff