Re: [PATCH net-next 1/2] tcp: remove per-destination timestamp cache

From: Eric Dumazet <redacted>
Date: Wed, 15 Mar 2017 15:59:01 -0700

On Wed, 2017-03-15 at 15:40 -0700, David Miller wrote:

quoted

From: Soheil Hassas Yeganeh <redacted>
Date: Wed, 15 Mar 2017 16:30:45 -0400

quoted

Note that this cache was already broken for caching timestamps of
multiple machines behind a NAT sharing the same address.

That's the documented, well established, limitation of time-wait
recycling.

People who enable it, need to consider this issue.

This limitation of the feature does not give us a reason to break the
feature even further as a matter of convenience, or to remove it
altogether for the same reason.

Please, instead, fix the bug that was introduced.

Thank you.

You mean revert Florian nice patches ?

This would kill timestamps randomization, and thus prevent some
organizations to turn TCP timestamps on.

TCP timestamps are more useful than this obscure tw_recycle thing that
is hurting innocent users.

Ok, I guess we can remove it in that case.  I'm still a bit disappointed
as I was always hoping someone would find a way to make this work even
in the presence of NAT.

I must be too optimistic.