Subject: Kex Error in X2Go client

From: promox <[email-masked]>
Date: Sat, 24 Jan 2015 12:53:19 +0000

Package: X2GO Client

Version: 4.0.3.1

Hi,
Before my server using ubuntu but now I am switching to centos. But when 
I connect to server using x2go. I got error message: kex error: no match 
for method server host key algo: server [ssh-rsa,ssh-dss], client 
[ecdas-sha2-nistp256].

Have anyway to fix that error?

---

From: Mihai Moldovan <[email-masked]>
Date: Tue, 03 Mar 2015 14:31:58 +0100

Control: reassign -1 x2goclient
Thanks

Hi

On 24.01.2015 01:53 PM, promox wrote:
> Package: X2GO Client
>
> Version: 4.0.3.1
>
> Hi,
> Before my server using ubuntu but now I am switching to centos. But
> when I connect to server using x2go. I got error message: kex error:
> no match for method server host key algo: server [ssh-rsa,ssh-dss],
> client [ecdas-sha2-nistp256].
>

This issue came up on the IRC channel a few days back and it looks like
your server is missing an RSA key.

Can you please run "sudo ssh-keygen -A", then restart the ssh daemon and
test again?

N.B.: there's nothing x2goclient can do about this situation, unfortunately.

Mihai

---

From: Michael DePaulo <[email-masked]>
Date: Tue, 3 Mar 2015 20:04:00 -0500

> N.B.: there's nothing x2goclient can do about this situation, unfortunately.

Mihai,

He already has an RSA key. And a DSA key. The problem is that X2Go
Client for Windows is limiting him to an ecdsa-sha2-nistp256 key. It
won't even accept other key lengths.

Promox,

You should run this command, then restart the ssh daemon:
ssh-keygen -f /etc/ssh/ssh_host_ecdsa_key -N '' -t ecdsa -b 256

-Mike#2

---

From: Mihai Moldovan <[email-masked]>
Date: Wed, 04 Mar 2015 03:07:59 +0100

> won't even accept other key lengths.

Sorry, I meant an ECDSA key.

Taken from man ssh-keygen:
``     -A      For each of the key types (rsa1, rsa, dsa, *ecdsa* and
ed25519) for which host keys do not exist, generate the host keys with
the default key file path, an empty passphrase,
             default bits for the key type, and default comment.  This
is used by /etc/rc to generate new host keys.''

The default ecdsa key generated on my machine is ecdsa-sha2-nistp256.

That's why I explicitly suggested (sudo) ssh-keygen -A.

Mihai

---

From: Michael DePaulo <[email-masked]>
Date: Tue, 3 Mar 2015 21:10:12 -0500

> That's why I explicitly suggested (sudo) ssh-keygen -A.

Sorry,  i skimmed the manpage too hastily. You are right, that is the
preferable command.

Thanks,

-Mike#2