In the past two weeks I set up a new VPS, and I run a small experiment. I share the results for those who are curious.
Consider that this is a backup server only, meaning that there is no outgoing traffic unless a backup is actually to be recovered, or as we will see, because of sshd.
I initially left the standard "port 22 open to the world" for 4-5 days, I then moved sshd to a different port (still open to the whole world), and finally I closed everything and turned on tailscale. You find a visualization of the resulting egress traffic in the image. Different colors are different areas of the world. Ignore the orange spikes which were my own ssh connections to set up stuff.
Main points:
-
there were about 10 Mb of egress per day due just to sshd answering to scanners. Not to mention the cluttering of access logs.
-
moving to a non standard port is reasonably sufficient to avoid traffic and log cluttering even without IP restrictions
-
Tailscale causes a bit of traffic, negligible of course, but continuous.
The best reason is reducing attack surface. It's such an easy thing to do. I don't know why people still expose services they don't need to.
Moving the port doesn't reduce attack surface. It's the same amount of surface.
Tailscale is a bit controversial because it requires a 3rd party to validate connections, a 3rd party that is a large target for threat actors, and is reliant on profitability to stay online.
I would recommend a client VPN like wireguard, or SSH being validated using signed keys against a certificate authority your control, with fail2ban.
You can run headscale to do your own validation.
It reduces the probability that a drive by scanner is going to detect a vulnerable service. Camouflage isn't a guarantee that you aren't going to be sighted on a battlefield, but it's still a good idea to reduce the probability of becoming a target in whatever ways you can.