[solved] Ssh into hosting service running rhel 6

I’m not sure of the exact source of the problem but perhaps someone knows how to work around the problem.

From either a 22.04 or Arch Linux system, I am unable to ssh into an old rhel hosting provider. I get the following error:

Unable to negotiate with xxx.xxx.xxx.xxx port 2222: no matching host key type found. Their offer: ssh-rsa,ssh-dss

I can get a little further if I add -o HostKeyAlgorithms=+ssh-rsa to my ssh command but instead get:

xxx.xxx.xxx.xxx: Permission denied (publickey).

My public key is authorized for the site. I have no problems ssh’ing from an older box (e.g., Debian Bullseye).

My best guess is that something has been deprecated in newer versions of either openssh or openssl.

Thoughts or ideas for a workaround?

There was an update to openssh recently, that made it incompatible with hosts running an older version of openssh, which I assume the RHEL 6 box is.

You best bet is likely to set up a VM with an older OS (like Ubuntu 20.04), transfer your ssh keys to that VM, and ssh from that VM to the RHEL6 box.

PS: I would recommend to update the RHEL6 box to a newer version, as basically any newer OS will have the new OpenSSH.

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Thanks, I found a simpler solution. Downloaded an older version of openssh, compiled it but did not install it. Should I need to access this hosting provider, I’ll use this older version I compiled.

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Another alternative would be getting/making an appimage for it.

Probably could run it in podman or docker too.

Thanks for the additional suggestions but I rarely need access to this box and an alias specifying the location of my compiled ssh does the trick. We’ll have to ask the web host to switch us to a more up-to-date host sometime this summer.