[OpenAFS] client behind NAT firewall

[chas williams - CONTRACTOR]

On Wed, 06 Aug 2014 15:33:02 -0400
Dale Pontius <pontius@btv.ibm.com> wrote:

> On 08/05/2014 11:08 AM, Simon Wilkinson wrote:
> > The complication is that firewalls/NATs only preserve these mappings 
> > for a finite length of time. We attempt to keep them open through 
> > regular fileserver pings, but sometimes that isn't enough. When a 
> > mapping expires, the client is unable to receive callbacks until it 
> > next contacts the fileserver.
...
> 
> Obviously this was client side, but I find it hard to believe that 
> keeping a connection mapped for the 2 hours mentioned elsewhere would be 
> necessary.

Interestingly enough, the time to live for callbacks varies based on
the number of users.  If your fileserver doesn't do pings, I think 2
hours might be a little short for some volumes.  From viced/callback.c:

/* Time to live for call backs depends upon number of users of the file.
 * TimeOuts is indexed by this number/8 (using TimeOut macro).  Times
 * in this table are for the workstation; server timeouts, add
 * ServerBias */

static int TimeOuts[] = {
/* Note: don't make the first entry larger than 4 hours (see above) */
    4 * 60 * 60,                /* 0-7 users */
    1 * 60 * 60,                /* 8-15 users */
    30 * 60,                    /* 16-23 users */
    15 * 60,                    /* 24-31 users */
    15 * 60,                    /* 32-39 users */
    10 * 60,                    /* 40-47 users */
    10 * 60,                    /* 48-55 users */
    10 * 60,                    /* 56-63 users */
};                              /* Anything more: MinTimeOut */

/* minimum time given for a call back */
#ifndef INTERPRET_DUMP
static int MinTimeOut = (7 * 60);
#endif