[X2go-User] Failure - Server Key

[Ivan Kabaivanov]

On Sunday 16 October 2011 13:42:52 Ivan Kabaivanov wrote:
> On Saturday 15 October 2011 20:40:53 CACook at quantum-sci.com wrote:
> > Just reinstalled Debian on the backup server, but now can't get into it
> > with x2go.  Gives a popup that says, "The host key for this server was
> > not found but an othertype of key exists.An attacker might change the
> > default server key toconfuse your client into thinking the key does not
> > exist."
> > 
> > Doing a search, no one seems to have had this problem before.  Any
> > ideas?
> 
> This happened to me.  Just a guess, have  you switched to newer openssh +
> openssl 1.x.x?  If so, openssh uses ecdsa-sha2-nistp256 keys by default, and
> x2go doesn't.  You can either disable ecdsa on the server, or delete the
> key from your known_hosts on the client, start x2goclient and it should
> pick the correct key.


On the server, open /etc/ssh/sshd_config and look for lines similar to these:

# HostKeys for protocol version 2
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key

If all of them are commented out, then the default ecdsa is used.  If you 
wanna force a non-default type, uncomment the corresponding line and restart 
sshd.  I believe you should be able to uncomment all three types and sshd will 
accept all of them.

IvanK.