PF slowing down file copies

[Giorgos Keramidas]

On 2007-02-22 14:30, RW <fbsd06 at mlists.homeunix.com> wrote:
>On Wed, 21 Feb 2007 19:38:39 +0100
>J65nko <j65nko at gmail.com> wrote:
>> For keeping state on TCP connections you should only create state on
>> the first packet of the 3 way TCP handshake. Using "flags S/SA" will
>> ensure this. This will prevent problems with TCP windows scaling..
>
> Why? Creating a state entry causes subsequent packets, in the same tcp
> connection, to bypass the rules altogether.

Because a state entry is a rule by itself.  A special 'rule', but still
a rule.  As such, each state-table entry requires a finite amount of
resources.  Conserving resources, whenever possible, is a good idea.

Creating 10 packets for a connection whose 'traffic' requires 10 TCP
segments to be transmitted, and 9000 state entries for a TCP connection
whose data payload needs 9000 segments to be transmitted is kind of
silly.  Especially since it is entirely legal and easy to do the same
thing with only 2 state entries (one for each connection).