'for fun' I pasted the text of your email in to chatgpt, it had some 
interesting advice:

*Verify User Exists*:  - probably not your problem.

*Check User's Shell*: Ensure that the user "default" has a valid shell. 
You can check the user's entry in |/etc/passwd|
|Good suggestion, imho, but you did imply you'd logged in as the user, 
so this is also (probably) a red herring.|
||
*Home Directory*: Ensure the user "default" has a home directory.
*SSH Key/Password*: If you're trying to log in using SSH keys, ensure 
that the public key is correctly placed in 
|/home/default/.ssh/authorized_keys| and that the permissions are set 
correctly
- since you've not logged in via SSH, this is probably also a herring.
However, the suggestion: If you’re using password authentication, make 
sure the user has a password set Might be helpful.
I'm skipping firewall suggestion.
*Log Files*: Since |/var/log/faillog| is empty, also check 
|/var/log/auth.log| for any messages related to SSH login attempts
- very good idea.
Three's more, but I'm guessing the log files are the most likely place 
to start, after the suggestions everyone else gave.

On 10/21/24 23:22, Rusty Carruth via PLUG-discuss wrote:
> The other questions are all great, but can you ssh from the server to 
> itself as the desired user?  That is, ssh theSSHdude@localhost , which 
> should hopefully rule out network issues ;-)
>
> I'll also mention that I had a weird issue with SSH where I could ssh 
> from machine A to machine B, but not from B to A!  THAT turned out to 
> be a netmask issue!  And ChatGPT ALMOST got the answer. You could try 
> your favorite AI to see if it can help, but be sure to give it more 
> info than you think you should - I should have given it the output of 
> ifconfig on both computers and it probably would have caught it....
>
> On 10/21/24 18:46, Keith Smith via PLUG-discuss wrote:
>> Hi,
>>
>> I am a little stuck.
>>
>> I am trying to configure a user that will allow me to log into an 
>> Ubuntu 24.04lts server via SSH.
>>
>> I created a line : "AllowUsers default" in /etc/ssh/sshd_config
>>
>> Then sudo systemctl restart ssh
>>
>> Try to login and get "client_loop: send disconnect: Broken pipe"
>>
>> sudo tail /var/log/faillog returns nothing.
>>
>> I can SSH into the server from my Kubuntu desktop under the default 
>> user created during server o/s install
>>
>> A search says it is probably a network issue.  Does not make sense 
>> given I can SSH in using another user.
>>
>> Any thoughts are much appreciated.
>>
>> Keith
>>
>>
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