MTU/MSS testing IPv6

[Matthew Luckie]

On 05/26/16 00:33, Ignatios Souvatzis wrote:
> On Fri, Apr 29, 2016 at 08:30:50AM +0200, Mikael Abrahamsson wrote:
>>
>> Hi,
>>
>> I've run into a scenario where a website doesn't seem to be listening to
>> PTB. I can reach them just fine from an MTU1500 clean IPv6 connection, but
>> if I reach from a MTU1500<->MTU1480<->MTU1500 connection, it doesn't work. I
>> don't get the big packets after SYN handshake.
>>
>> I've been considering asking iis.se (the .SE ccTLD registry) who are already
>> running multiple testing tools for web sites and domain name owners) to
>> include these kinds of testing, and perhaps develop more of them.
> 
> Yes please.  Guess what I'm trying to debug right know, and having a 
> reliable testing point out there would be an immense help.

Try using

http://wand.net.nz/pmtud/webserver.php

one caveat: it assumes http, rather than https.  That made sense in
2010.  This limitation can be fixed if there is demand.

Matthew