TCP Fast Open (RFC7413) for FreeBSD

[Patrick Kelsey]

> On Sep 2, 2015, at 12:54 AM, Rui Paulo <rpaulo at me.com> wrote:
> 
>> On Tue, 2015-09-01 at 21:19 -0400, Patrick Kelsey wrote:
>> Hi,
>> 
>> About two weeks from now, I will be starting work on server-side TCP 
>> Fast
>> Open (TFO) support for FreeBSD head and stable/10, with the intention 
>> of
>> having patches up for review by November.  This message is an attempt 
>> to
>> uncover any existing work on TFO for FreeBSD, as the existence of 
>> such work
>> may change my plans.
>> 
>> Copying Sara Dickinson and Tom Jones due to this thread:
>> https://lists.freebsd.org/pipermail/freebsd-net/2015
>> -January/040910.html.
> 
> Have you performed any measurements on the likelihood that stateful
> packet inspectors (firewalls, NATs, etc.) will allow a SYN or a SYN/ACK
> to pass with data in it?

I have not performed any such measurements.  This issue is discussed in section 7.1 of the RFC, which cites such studies and summarizes the finding as being that 6% of the probed internet paths dropped SYN packets with data or with unknown TCP options.


> 
> How would this interact with our syncache?  Does it just need to store
> the cookie?
> 

The exact interaction with the syncache is still TBD, but I do not expect to be storing TFO cookies in the syncache as the cookies are per client-server IP pair and not per-connection.

-Patrick