On Tue, 2014-08-05 at 09:30 +0200, Alex wrote:
> Now, I didn't find in the admin guide or wiki[1] some useful
> information
> about client's firewall, but I could find some information on the
> Internet saying that client doesn't work without opening 7001 for
> incoming UDP [2]. This should be open for callbacks (if I understood
> correctly). I also tested the client behind NAT with some public cells
> and it worked well. So, does a client work behind a firewall NAT even
> without opening inbound ports? If not, is there any solution for this?

You will get basic client functionality even without opening the port.
What you won't get is notifications from the server that something the
server knows to be cached on the client has been modified elsewhere and
the client should flush its cached information (this is the "callback").

In most cases, clients already discard this cached information after
some amount of time; additionally, if you are mostly using read-only
volumes then the cached information would only be invalidated by a new
volume release. In addition, even if you open the port, most NAT
implementations don't retain UDP NAT mappings for long enough to be
useful for callback breaks (generally their expected use case for UDP is
DNS). So you might be able to get by with just running "fs checkvolumes"
periodically in a cron job to make up for missing callback breaks on
volume releases. For the most reliable operation, however, you should
check that the NAT gateway can remember UDP NAT mappings *specifically
on client port 7001* for at least 2 hours and open 7001/udp in the
firewall so the client can receive callback breaks.

-- 
brandon s allbery kf8nh                           sine nomine associates
[email protected]                              [email protected]
unix openafs kerberos infrastructure xmonad        http://sinenomine.net
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