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. This manifests as the session "freezing" - text entered into a shell or text editor is intermittently delayed by as much as 10-15s in some cases. It occurs with such frequency the shell sessions become unusable. Initially I suspected a network issue. Packet captures on the client side show many TCP retransmissions during the events. On the OpenBSD side, these are identified as spurious retransmissions. I've checked and fiddled with MTU, MSS, etc. to no avail. Examined routers, switches, SSH settings. It does not matter if the client/server are on the same or different VLANs. Multiple OpenBSD boxes are affected, running on different hardware platforms, different hypervisors, etc. Now for the curve ball. I've a dozen Linux servers on this network and none experience this issue at all. Furthermore, if I SSH into a Linux box first, then SSH from there into the OpenBSD box, the issue goes away. Any ideas where I should look next? Regards Lloyd
