[p2p-hackers] UDP ports in the dynamic range

[David Barrett]

That's good to keep in mind, thanks.

Adam Fisk wrote:
> The only thing that comes to mind here is that some apps like RealPlayer 
> and likely Windows Media Player and Quicktime select UDP ports from 
> fairly broad ranges, at least the last time I checked.  I don't remember 
> what those ranges were, but it's quite likely they're choosing a subset 
> of the dynamic range as well, so you might just want to take a second to 
> check for an overlap.  It's probably fine and not really something to 
> worry about -- just putting it on your radar.
> 
> -Adam
> 
> 
> David Barrett wrote:
> 
>> From range of ports should I randomly pick a UDP port mapping?
>>
>> The IANA states "The Dynamic and/or Private Ports are those from 49152 
>> through 65535".  Thus I'm considering just randomly selecting from 
>> within this range.
>>
>> However, I'm curious if you have any experience with this and and 
>> either encourage or dissuade me along this path?  I personally don't 
>> care which port I use, so long as I don't stumble into some "known" 
>> minefield.  Do firewalls often block this range?  Do NATs do anything 
>> funky with this range?  Is there any reason to use one UDP port over 
>> another?  Should I secretly use on of the registered ranges to improve 
>> my NAT/firewall penetration odds?
>>
>> An alternate plan is to choose an unregistered range from the big IANA 
>> list (http://www.iana.org/assignments/port-numbers) but if there's no 
>> reason not to, I'd just as soon stick with the big unregistered 
>> dynamic range.
>>
>> Any suggestions?
>>
>> And finally, I'm going to try to configure a UPnP port-mapping using 
>> this randomly-selected port as my external NAT port.  Does this change 
>> your recommendations at all?
>>
>> -david
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