On Fri, Dec 18, 2020 at 3:53 AM Alexandr Nedvedicky
<[email protected]> wrote:
>
> Hello Sven,
>
> your change makes me wonder: 'what is the actual problem you are trying to
> solve'?
>
> the reason I'm asking is that latency is just one factor, which contributes to
> TCP connection performance. The other factor (and perhaps more important) is 
> to
> guess amount of retransmitted data. Processes (a.k.a. endpoints), which
> communicate over TCP can experience significant delay once TCP packets starts
> to be dropped. Those dropped TCP packets contribute to delay experienced in 
> the
> more significant way, than 'network latency' in sense of roundtrip.
>
> I'm not much experienced firewall administrator, the only firewall I run is
> APU box at my home, hence I'm sorry if my question sounds naive. So basically
> what sort of problem in network you hope to diagnose with PF?
>
> And also don't get me wrong: I like your idea to extend PF to enable firewall
> to provide better picture of what happens on network. I just want to point
> out that sampling network latency (round-trip) might not be sufficient.
>
> thanks and
> regards
> sashan
>

I need data on perceived server load // compare to network jitter with
different locations.
The retransmission global counter, while interesting, is certainly not
perfect either.

But for now I'd like to be able to keep a record of the latency of
'real' TCP connections.
I cannot do it on the clients, and cannot do it on the servers. It
must be done in
the trusted OpenBSD environment. Having retransmissions per tcp connection
would definitely be a plus, but it's not the goal here. It is not a
problem I need to solve,
just additional data I want to extract to make better informed choices
and cross validate results.

I would like to go through this one step at a time to stay focused on :
computing latency timing of TCP connexion in openbsd 'correctly'


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