Although disabling the root user is a good part of security, leaving it enabled should not alone cause you to get compromised. If it did, you were either running a very old version of OpenSSH with a known flaw, or, your chosen root password was very simple.
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Basic setup for me is scripted on a new system. In regards to ssh, I make sure:
- Root account is disabled, sudo only
- ssh only by keys
- sshd blocks all users but a few, via AllowUsers
- All 'default usernames' are removed, like ec2-user or ubuntu for AWS ec2 systems
- The default ssh port moved if ssh has to be exposed to the Internet. No, this doesn't make it "more secure" but damn, it reduces the script denials in my system logs, fight me.
- Services are only allowed connections by an allow list of IPs or subnets. Internal, when possible.
My systems are not "unhackable" but not low-hanging fruit, either. I assume everything I have out there can be hacked by someone SUPER determined, and have a vector of protection to mitigate backwash in case they gain full access.
You should turn off ssh password logins on external facing servers at a minimum. Only use ssh keys, install fail2ban, disable ssh root logins, and make sure you have a firewall limiting ports to ssh and https.
This will catch most scripted login attempts.
If you want something more advanced, look into https://en.m.wikipedia.org/wiki/Security_Technical_Implementation_Guide and try to find an ansible playbook to apply them.
Just turn off password logins from anything but console. For all users. No matter where it runs.
It becomes second to nature pretty fast, but you should have a system for storing / rotating keys.
And this is why every time a developer asks me for shell access to any of the deployment servers, I flat out deny the request.
Good on you for learning from your mistakes, but a perfect example for why I only let sysadmins into the systems.
We have it at my company its just a very small group and we have to manually enable it for production and its through tools like teleport. Staging and the like its free game there for them for debugging, same infra through. Gives us best of all worlds
Interesting. Do you know how it got compromised?
I published it to the internet and the next day, I couldn't ssh into the server anymore with my user account and something was off.
Tried root + password, also failed.
Immediately facepalmed because the password was the generic 8 characters and there was no fail2ban to stop guessing.
because the password was the generic 8 characters and there was no fail2ban to stop guessing
Oof yea that'll do it, your usually fine as long as you hardened enough to at least ward off the script kiddies. The people with actual real skill tend to go after...juicer targets lmao
Don't use passwords for ssh. Use keys and disable password authentication.
More importantly, don't open up SSH to public access. Use a VPN connection to the server. This is really easy to do with Netbird, Tailscale, etc. You should only ever be able to connect to SSH privately, never over the public net.
wow crazy that this was the default setup. It should really force you to either disable root or set a proper password (or warn you)
Love Hetzner. You just give them your public key and they boot you into a rescue system from which you can install what you want how you want.
I think their auction servers are a hidden gem. I mean the prices used to be better. Now they have some kind of systrem that resets them when they get too low. But the prices are still pretty good I think. But a year or two ago I got a pretty good deal on two decently spec'd servers.
People are scared off by the fact you just get their rescue prompt on auctions boxes... Except their rescue prompt has a guided imaging setup tool to install pretty much every popular distro with configurable raid options etc.
Yeah, I basically jump from auction system to auction system every other year or so and either get a cheaper or more powerful server or both.
I monitor for good deals. Because there's no contract it's easy to add one, move stuff over at your leisure and kill the old one off. It's the better way to do it for semi serious stuff.
Now that you mentioned it, it didn't! I recall even docker Linux setups would yell at me.
Ah, timeless classic.
Any idea what ip addresses were used to compromise it?