[p2p-hackers] NAT hole-punch keepalive/timeouts

[David Barrett]

Ok, sounds like 20 seconds might be an upper limit, then.  Are you using 
"unconfirmed" keepalives, or bidirectional?  Thanks for the info.

On Sun, 5 Jun 2005 7:26 pm, Alex Pankratov wrote:
> I am aware of at least one fairly big firewall vendor whose devices
> default to 20 sec UDP rule lifetime. It is even less if the traffic
> is unidirectional (ie 'unconfirmed' by the recepient). We are using
> 20 sec and seems to work fine for our purposes.
>
> Alex
>
> David Barrett wrote:
>
>> Ok, next question: What kind of keepalive period do you used to 
>> maintain the holes you so meticulously punched?
>> I'm in the process of testing my NAT hole-punching solution, and I'm 
>> finding erratic behavior that I *think* is caused by my holes closing 
>> on me.  (Ie, I'm able to receive from a peer for a time, and then I 
>> cannot.)  So I'm implementing a keepalive, but I'm unsure of what 
>> period to use.  For now I'm just using a fixed 20-second period, but I 
>> have no idea if that's high or low.
>> Another option is to have some kind of adaptive solution that tracks 
>> elapsed time between sent and received data (thus estimating the last 
>> known 'good' window), but that's a pain I'd prefer to avoid.
>> Any suggestions?
>> The IETF BEHAVE group has discussed recommendations from anywhere 
>> between 30 seconds 
>> (http://list.sipfoundry.org/archive/ietf-behave/msg00441.html) and 15 
>> minutes 
>> (http://list.sipfoundry.org/archive/ietf-behave/msg00127.html).  But 
>> ultimately those are foward-looking discussions, and therefore not 
>> relevant.
>> In the real world, I've seen mention that even 30 seconds is 
>> insufficient 
>> (http://www.frameip.com/nntp/article-comp-protocols-tcp-ip.php?numero=20119).  Perhaps 20 seconds works (http://www.tisc2001.com/newsletters/322.html), but who knows.
>> Basically, I'm curious what keepalives you've found work today in your 
>> real applications, in the real world.
>> -david
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