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Background: I’ve been researching a new problem that manifests as a dropped (broken pipe) connection during ssh sessions. Several forum searches turn up bug reports that seem to me are misdirected. The problem started for me when I upgraded to openssh 7.6 on Mac OS Mojave. During rsync backup sessions over ssh I started getting the broken pipe disconnects that never happened before. Apparently, openssh 7.6+ had a change where it started using DSCP (QoS) packets received during the session. From my research, the root cause points to the Comcast network sending malformed IPv4 DSCP packets, and this has been a problem for many years. Now, recent versions of openssh are trying to use this information and having trouble. A temporary workaround is to use a “IPQoS=throughput” setting in ~/.ssh/config.
Question: Can anyone confirm this, and would this be considered a openssh bug (rather than other bug reports I’ve seen blaming other things)?
John Benford
Posted 2019-04-14T21:15:49.857
Reputation: 1
You have just said yourself that it's a Comcast network problem, haven't you? – user1686 – 2019-04-15T04:36:23.663
Yes, but I’m not sure because I haven’t found bug reports on it for openssh. – John Benford – 2019-04-15T14:29:00.960
I've had the same issue (after upgrading to Catalina). See https://apple.stackexchange.com/questions/374280/interactive-ssh-blocked-with-catalina/374287#374287
– Benoît – 2019-11-04T12:31:09.670