Hi all,
I'm having trouble getting the x2go client to authenticate with passwordless login options other than kerberos. Specifically, I've tried auto login (via SSH agent) and supplying the path to my OpenSSH private key (which is an ECDSA key).
Kerberos works for me as long (as I have a valid ticket), but I want to connect using the the ECDSA key, for reasons I'll explain below.
I suspect that the ECDSA format key is not supported by my current client version, but if someone could confirm (or deny) that, I would appreciate it; and if it's possible that it might work with a more up to date client build / build against an updated LibSSH or something, that would be good to know too. I don't currently have the wherewithal to build my own copy of the client for MacOS, but that might provide some incentive for me to try sometime soon.
Some background: I'm using x2go at work to connect from my Macbook Pro to a Linux server. To connect using Kerberos, I need a valid ticket, and to get a valid ticket, I need to first connect to the corporate VPN. However, I don't need to connect to the VPN in order to use SSH (from a terminal), thanks to a proxy software (a ProxyCommand in my ~/.ssh/config).
If I already have a valid Kerberos ticket, the X2go client will connect using Kerberos, without VPN (that is, the ProxyCommand seems to work). However, I don't want to have to connect to the VPN just to renew my kerberos ticket when ssh itself will work using the ECDSA key I obtain. (It will also work using my password, but that is a temporary measure... my employer is phasing out password-based ssh in favor of requiring U2F).
To be clear, the proxy command doesn't seem to be the issue; I encounter the same problem when I'm connected to the VPN.
I've attached two files (with usernames and hostnames substituted), one the output of ssh -vvv (succes) and the other the output from /Applications/x2goclient.app/Contents/MacOS/x2goclient --debug (failed). Both were run while connected to the VPN. The x2go session was set up with "Try auto login" checked, Kerberos 5 unchecked, and "Use RSA/DSA key" left blank (the log also shows that the contents of my ssh agent were valid in the terminal). Trying after supplying a path to my ~/.ssh/id_ecdsa file under "Use RSA/DSA key" has the same result.