What do I need to learn to understand SSH setup on OS X Catalina?

Posted January 18, 2020 1.3k views

Is there any manual configurations I need to add to Catalina? I can not ssh to my droplets after upgrade to Catalina, i tried using ssh -i and tried adding a ~/.ssh/config but none of that is getting me to ssh like I used to. The best I achieved I was able to get to the server but then the shell would hang on the last step of getting into the server. I see the welcome message of the server but I can not execute commands nor use the shell as if I am in the server, never seen that before!

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2 answers

So I just found that I need to add -o IPQoS=throughput to my ssh flags and that solved the problem!

It looks like this is a digital ocean specific issue, and not due to my catalina update, the issue I ran into is described here, scroll to section SSH hangs.
`Possible cause

With some routers behind NAT and when using OpenSSH. During session setup, after the password has been given, OpenSSH sets the TOS (type of service) field in the IP datagram. The router choke on this. The effect is that your SSH session hangs indefinitely. In other words, SSH commands or connections are seldom working or not working at all.