Second is to disable root login.
Third is to copy my private key over and disable password login.
3 essential steps to secure SSH.
[0]: https://docs.freebsd.org/en/books/handbook/firewalls/#firewa...
One IP abusing it and trying to gain access isn't what I address by moving the port. I move the port to cut out the noise of the thousands of IPs that will connect to it once to probe it and never again. The volume of those one-off probes is so dramatic that it makes the logs entirely useless. By moving the port, I cut out that noise so that if I glance at the logs I actually have a chance of noticing anything that is worth noticing.
1) Setup a VPN via wireguard and only expose that random udp port. That way only a single UDP port is exposed and port-scans become infeasible.
2) Setup 2fa via libpam-google
That's the one thing that's prevented me from actually doing this.
FWIW, I’ve been using Wireguard for a while (probably ~2 years?) as an always-on VPN for multiple mobile devices, and also as a reverse tunnel to pinhole service access inside a LAN. The Wireguard config and daemon has been rock solid. The only time it’s failed is when I messed up the AllowedIPs, but that failure occurs at configuration time. It has never crashed, or stopped routing traffic correctly, or otherwise failed in a way that interrupted traffic flows.
I guess I'll give it a try for some time.
i.e. Each hub has 1 VPN in, or is connecting 4 ways out.
If the port forwarding or something fails inbound, then I can connect via another VPN and try and debug/diagnose what is wrong.
If all VPNs are reporting down, then I know the pi/internet is completely down. It will either restart connectivity, but I have someone there who can plug/unplug/restore the system if necessary. The same kind of problem would occur if ssh falls over or wireguard.
wireguard tunnels are pretty robust to failure.
they can survive you changing your wifi access point and IP for example.
But I find VPN a bit overkill on my personal machines.
Also a globally accessible pihole connected to DoH which ensures somewhat global privacy.
They are basically my perfect use for my raspberry pis. Extremely low power, but perfectly capable for handling say 1080p video streams or to RDP into machines for access to cross-country resources.
Changing the port and using a non-root user for SSH don’t appreciably change the strength of the server’s security.
Active alerting on brute force attempts on an internet-facing SSH service is an exercise in human suffering. At best you don’t get any alerts, and at worst you get alerts that you do… what, precisely, with? Block the IP? Look up the “human” attacker and send them an email asking them to stop?
There are environments and entities for whom pattern detection on incoming connections makes sense, and those environments aren’t running internet-facing SSH.
I’m specifically saying that the act of reading SSH logs for an internet-facing server is an exercise in futility. The kinds of things that will show up in the logs (brute force attempts, generally nmapping, etc) are not credible risks to even a largely unconfigured SSH daemon (as noted elsewhere in this thread, the bar to have an above average secure SSH service is basically “apply pubkey, disable password auth, celebrate”).
The attackers that are problematic don’t look out of place in your logs: somebody who stole a valid pubkey/password, the unlikely case of an SSH zero day, etc. Those are going to be single access attempts that just work. Unless you’re literally alerting on every successful auth, the logs aren’t helping you for active alerting.
Keeping your internet-facing SSH logs is important for investigative work: once you find out that your buddy accidentally put their private key in a pastebin, you can check if somebody used it to log into your server.
I changed my port to a random 4 digit number. Not a single failed login attempt in 6 months.
Obviously follow good security practices too but I like not have to rotate and filter the logs with yet another tool.