cannot log into Ubuntu 16.04 server with ssh keys

@technicallyblue

I would recommend simply shutting down the firewall service using Console and see if that allows you to log back in via SSH. You can do that by running:

ufw disable

If you’re able to login with ufw disabled, then your IP was most likely blocked. Normally, I recommend using actual ports over defined services when setting up ufw. Using actual ports seems to be far less problematic.

So if you’re able to login with ufw disabled, I’d now run a reset to wipe all existing rules.

ufw reset

You now have a clean slate from which to work from. So let’s rebuild.

We’ll start with default rules. We’ll deny all incoming and allow outgoing. These rules won’t matter as right now, ufw is disabled, so you shouldn’t get locked out when running them if you ran both of the commands above.

ufw default deny incoming

ufw default allow outgoing

Now we need to specify which ports to allow in. I always start with SSH since that’s the first thing I’ll be using and it’s the most important to start with.

Now, from the looks of it, you’re using another port – from what I’ve read, that’s 5069, though let’s confirm that to make sure so that you don’t end up getting locked out again.

Please run:

grep "Port" /etc/ssh/sshd_config

You’ll see a port echo’ed out to the screen that looks like Port ... where ... is the port. If that says 22, then we’ll use 22. If it says 5069, then use that.

So let’s allow SSH. As above, change 22 to the other port if that’s what’s showing in your SSH config.

ufw allow 22/tcp

Now since you’re using Apache and LetsEncrypt, we need to allow HTTP and HTTPS connections, and we can do that by allowing ports 80 and 443 through.

ufw allow 80/tcp

ufw allow 443/tcp

At this point, unless you need to allow additional ports through, we can go ahead and start ufw back up and let it resume.

ufw enable

You’ll get a warning that you may be kicked, but as long as you used the correct SSH port in the above command, you’ll be fine.

Hopefully that helps to get you back in :).

@technicallyblue We’ve maxed out the other thread, so starting a new. Sorry, run this again, because I specifically used to “numbered” to avoid getting the canonical names:

sudo ufw status numbered

And then run this:

sudo lsof -iTCP -sTCP:LISTEN -P

@technicallyblue Make sure the file /etc/ssh/sshd_config has the line Port 5069 and reboot the server after the change. It seems like you’ve added a firewall rule to block port 22 - at least that’s what I’m seeing when scanning your server:

22/tcp  closed ssh

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