On Tue, 2 Oct 2018 at 19:33, Karen Lewellen via talk <talk@gtalug.org> wrote:

Hi folks,
The accessible ssh client I use provides a way to send dh keys when I use
ssh TELNET to reach a location.
I have a bell dsl account, and since the first of July I have not been
able to reach dreamhost who hosts my office shell.
While I have not ruled out Bell as the problem, it started one day when
they claimed to have a service interruption, and refuse to discuss Linux
at all, I want to see if something else might have happened.
With very few exceptions, every place where I visit involving port 22
presents the same dh key exchange failure.
Was openssh updated on June 29 2018?
Hosting companies who use some different Linux options for their shell
services, scientific for example, still work. Shellworld does too, but we
use a different port for ssh and the administrator still allows most
public keys.
can anyone provide wisdom here?
Thanks,
Karen

Many technical answers have been given. I would suggest starting with some simple debugging.

$ telnet dreamhost.com 22

These days, a lot of distros don't have 'telnet' installed because it's considered insecure. And they're not wrong - but it's also very useful for debugging. So install it if it's not available. Then try the above command line, which asks telnet to try to connect to dreamhost.com on port 22 (which is the standard SSH port). (You should use whatever host name you would normally SSH to, which may be "someotherhost.dreamhost.com.") This is a connection that can't be completed, but it can still tell you something. If someone in between is blocking port 22 (most likely Bell, but could be any intervening firewall possibly on your own machine or at your office), this attempt will fail entirely. If, however, port 22 is available, you should see something like this:

    $ telnet dreamhost.com 22
    Trying 192.237.213.194...
    Connected to dreamhost.com.
    Escape character is '^]'.
    SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.10

This means you can reach your desired host over port 22, and the problem is something else (such as all the technical stuff that's already been discussed). I just think it's good to start here.

P.S. telnet has now left you stranded: as it suggests, hit Control-] (the close square bracket) and then type 'quit' at the 'telnet>' prompt.

P.P.S. Looks like Dreamhost's main machine is using a very old version of SSH ... 7.4 is current.

Giles
https://www.gilesorr.com/
gilesorr@gmail.com