On Sat, Dec 14, 2024 at 06:51:49PM +, Lloyd wrote:
> Any ideas where I should look next?
When it comes to network issues, I like to run and review the following:
$ netstat -s
Another source of quality-of-service problems is if you use a different
port for ssh (or whatever) that some router somewhere turns out to have
a problematic QoS set by default. Weird latency problems or staring at
tcpdump outputs for hours isn't much fun?
On Sunday, December 15th, 2024 Kirill A. Korinsky wrote:
> Do you mean set tos at pf?
Yes, though I now know QoS can be set in sshd directly.
Indeed, specifying <> in sshd_config made the problem
immediately disappear. I could induce it 100% of the time by simulating traffic
congestion (e.g. st
On Sun, 15 Dec 2024 21:12:56 +0100,
Lloyd wrote:
>
> Can I use pf to tag egress traffic as 0x00 and see if it goes away?
>
Do you mean set tos at pf?
--
wbr, Kirill
> (and I don't mean only the options explicitly set on sshd_config,
> the defaults might also be different).
Sadly this appears to be the case. Despite comparing sshd_config ages
ago, I have identified a possible solution, adding:
IPQoS lowdelay throughput
to /etc/ssh/sshd_config on the OpenBSD
> Have you tried to capture a traffic which contains an example of this packet
> loss?
Inspecting the captures a bit more closely, I see that OS X sets the DSCP field
in the IP header to 0x48 for SSH traffic - as does OpenBSD in its replies.
Linux sets this value to either 0x00 or 0x10 as does
On Sat, Dec 14, 2024 at 06:51:49PM +, Lloyd wrote:
> I've a particularly vexing problem for which I've been unable to
> identify the cause despite much research.
>
> There is an older Mac client on my network which experiences routine
> packet loss when connected to OpenBSD boxes over SSH. Thi
On Sun, 15 Dec 2024 19:53:02 +0100,
Lloyd wrote:
>
> Strangely, I can spray packets at this OpenBSD host using iperf3 at nearly
> full rate over the wireless network (~ 250Mbps) with zero packet loss.
> Only SSH seems to be impacted.
>
Have you tried to capture a traffic which contains an exampl
> You are implying the issue is with OpenBSD
Not at all. If anything I suspected a network misconfiguration and OpenBSD
responsible for uncovering it.
> Send your pf.conf and your ifconfig
pf.conf is OpenBSD default and ifconfig is bog standard /24 network with MTU
1500.
Additional testing no
You are implying the issue is with OpenBSD, because if you SSH into Linux
first, the issue does not happen.
Send your pf.conf and your ifconfig - probably is an MTU or firewall issue,
and others will be able to help with those.
On Sat, Dec 14, 2024, 3:55 PM Lloyd wrote:
> I've a particularly
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