TCP Simultaneous Open support

[ueberbill]

Do any versions of Linux support TCP Simultaneous Open? Does it work? Are there any issues? How can I find out more- scouring the search engines hasn't given me a whole lot.

Thanks,
Bill

 

[pansophic]

I'm not sure I know what you mean by "simultaneous open."

What is it that you are trying to do?


pansophic

 

[ueberbill]

Simultaneous open refers to the two hosts who are trying to communicate via TCP sending SYN packets at the same time and then both replying with ACK packets as opposed to the standard 3-way handshake. There's a diagram of simultaneous open at

http://ttcplinux.sourceforge.net/documents/two/ttcpstate/ttcpstate.html

, just search for 'simultaneous open'.It's legal in the TCP spec, but I read that it's not always implemented well or at all.

Thanks,
Bill

 

[Clairvoyant1332]

I tried doing this before and was successful on Solaris 2.6, but not on 2.5.1.

 

[Clairvoyant1332]

What are the applications of this, anyway?

 

[ueberbill]

Well, we're looking at working around some TCP NAT issues, although the timing of a simultaneous open makes it almost useless out of laboratory conditions (at least when trying to punch holes in a NAT setup).

Bill

 

[bcastner]

UDP?

 

[bcastner]

ueberbill,

NAT traversal can be a pain, but is surmountable.

. You could write to H.323 :

http://www.microsoft.com/windows/NetMeeting/Corp/reskit/Chapter11/default.asp

. You could make the port forwards uPnP compliant

. You can give the user clear instructions how to make port forwarding entries in their routers. Somehow there are millions of P2P users out there that have managed to figure out port forwarding issues to handle NAT Traversal.

. You can use third-party applications. As I do not know what you are trying to do, you might look at what others have done as general solutions for the end users:

. For Windows Win9x:

http://www.practicallynetworked.com/sharing/xp_ics/index.htm?image.x=51&image.y=18

Poke around the site for a freeware ICS tool.

. For Win2k/XP:

http://www.practicallynetworked.com/sharing/xp_ics/internetgateway.htm

Same site, different OS.