all network people please review this proposal: because someone is going to commit it soon. D5017

[Slawa Olhovchenkov]

On Fri, Jan 20, 2017 at 11:00:18PM +0800, Julian Elischer wrote:

> Unless eri gets to it first I will.
> 
> see https://reviews.freebsd.org/D5017
> 
> If you have a server, you can put an arbitrary number of clients on 
> the same port number because they all have different addresses.
> 
> However in the case of a client accessing multiple servers we are 
> limited to 65535 sessions because we strictly don't allow the same 
> port to be used more than once. This is silly because TCP is a 
> symmetrical protocol and of it works for the server it should work for 
> the client.
> 
> So this patch changes the allocation of ports to allow the client to 
> use a port that has been used before as long as the previous port user 
> is not talking to the same host/port. This removes the limitation of a 
> freebsd machine being only capable of contacting 65000 hosts in a 
> single port shutdown timeout period. With modern machines capable of 
> initiating  MILLIONS of sessions per second, having a limitation of 
> 65000 per 2 minutes is a bit silly.
> 
> 
> Please read the patch if you suspect this will have a bad effect of 
> any sort.  Once the session is started there is no record as to who 
> started it so any issues would have to be in the startup phase.

Good.
Can you use also destination port and source IP in same way as
destination address?