ProxyJump used to work, now throws "Unable to negotiate with UNKNOWN port"

Question

I have been connecting to a machine through another machine using ProxyJump for a few years now.

Host second-machine
    User my_username
    ProxyJump first_machine

Last week, after a MAC OS update to Ventura 13.0.1, I began receiving this error when I ssh to the second machine:

Unable to negotiate with UNKNOWN port 65535: no matching host key type found. Their offer: ssh-rsa,ssh-dss

However, I can ssh to the second machine if I ssh to the first and then to the second machine.

Searching online, people have suggested adding HostKeyAlgorithms +ssh-rsa to ssh config file. This allows me to ssh with ProxyJump but it asks for the passphrase every time.

Any ideas what happened?

Answer 1

I had the same problem (also macOS Ventura). This thread suggested another option: PubkeyAcceptedKeyTypes, and that worked for me.

So try something like this:

Host myServer
  HostKeyAlgorithms +ssh-rsa
  PubkeyAcceptedKeyTypes +ssh-rsa
  ProxyJump myJumpHost