I have a server where I believe I have disabled root login via ssh. I think it is done correctly, as I cannot login with root myself via ssh, but I would’ve thought that it would be reflected in /var/log/auth.log. Instead, it shows up as failed password entry. Is this intended?...
Ok, thanks - so if I understand correctly then, it is listening on port 22 as a default, and not accepting traffic on any port.
That brings of the question: wouldn’t I be better off changing the SSH-port? And is that so easy as to uncomment the #Port 22 line in the config file and changing the port number to something random, and saving that somewhere? Would I then be able to connect by running ssh myuser@mydomain.com:, or would I need to do anything else to successfully connect?
Yes that’s the right way to block root login. An added filter you can use the ‘match’ config expression to filter logins even further.
Not sure what you meant about the ‘match’ config expressions here. Could you elaborate a bit further?
If you’re on the open network, your connection will be heavily hit with login attempts. That is normal. But using another service like Fail2Ban will stop repeated hits to your host.
Hehe, yeah, I’ve noticed… The reason I get a little anxious whether I did this correctly, is that 95% of the login attempts are to root, so I want to make sure it is disabled. I have set up Fail2Ban, but I am using default settings, which may be a bit laxer than they need?
I’ve also been advised and considered moving to ssh keys, but I have not gotten to that yet.
Ssh listens on port 22, as soon as a connection is made the host moves the connection to another port to free up 22 for other new connections.
Makes sense. One question that comes from this is: is it possible to disable that? I would never need two ssh-logins at the same time on my server. And the second question is what I asked above regarding whether I should change the port ssh listens to in order to reduce unwanted malicious login attempts?
Just keep in mind that security through obscurity is not considered secure in itself.
Do you consider it to not be a helpful measure to take at all?
I have fail2ban configured - since it is reading from the auth.log, I guess I would not have to make any changes to the configuration there to have it work with a new port?
Edit: oh, you’re talking about the high port OP is wondering about. That’s just the source port, which is chosen randomly by the client OS when making a connection. Using port 22 (or any other port below 1025) as a source port would require root privileges on the client and would also conflict with the SSH server that could be running there. Still, it has nothing to do with SSH “moving connections over”
Ah, I see, so the port numbers shown in auth.log are all client side ports. I guess I thought that the listening port would be in the log and assumed that the port listed there would be it, but when I read the lines again, it clearly says “from ip.ad.dr.ess port 12345”
Have I successfully blocked ssh logins to root?
I have a server where I believe I have disabled root login via ssh. I think it is done correctly, as I cannot login with root myself via ssh, but I would’ve thought that it would be reflected in /var/log/auth.log. Instead, it shows up as failed password entry. Is this intended?...