Join GitHub today
GitHub is home to over 28 million developers working together to host and review code, manage projects, and build software together.Sign up
"Simultaneous open of TCP connections" is not supported. #58
Correcting myself here. :)
Thanks for making me learn something new! ;)
Lol. Still, I admit I could have been more wordy.
I case someone else wants a summary:
"Simultaneous open of TCP connections" is when all of the following conditions are met:
As cetex mentioned, this happens very rarely. I far as I know, there is no reason why anyone would actually actively want this to happen (even as an attack, AFAIK); it's simply a sporadic phenomenon TCP is supposed to handle gracefully. Also, it doesn't affect other connections at all.
Instead of doing what the RFC wants, Jool simply drops the IPv4 connection attempt. Jool will not crash, but what happens at the endpoints is somewhat implementation specific. In the worst case, they will simply have to reattempt the connection.
Update 2014-06-25: This is currently being worked at https://github.com/NICMx/NAT64/tree/issue58.
My understanding of the consequences of the current implementation have changed.
This is what the RFC wants us to do:
If Jool receives a IPv4-TCP connection request, the packet should be stored.
This is what Jool currently does:
If Jool receives a IPv4-TCP connection request, the packet is discarded.
Because the end result is the same in both second bullets, it just so happens that Jool has supported Simultaneous Open of TCP connections all along. What it does poorly is is let IPv4 nodes know that their TCP connections cannot be made when there is no Simultaneous Open...