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:
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there were about 10 Mb of egress per day due just to sshd answering to scanners. Not to mention the cluttering of access logs.
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moving to a non standard port is reasonably sufficient to avoid traffic and log cluttering even without IP restrictions
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Tailscale causes a bit of traffic, negligible of course, but continuous.
I don't get why people leave interfaces the public doesn't need access to open to the public -- especially SSH.
Use a VPN if you need access to those interfaces from the "outside". They're stupidly easy to set up these days, particularly with Wireguard.
A VPN is easy to setup (and I have it setup by the way), but no VPN is even easier. SSH by itself is sufficiently secure if you keep it up to date with a sane configuration. Bots poking at my ssh port is not something that bother me at all, and not part of any attack vector I want to be secure against.
Out of all the services I expose to the clear web, SSH is probably the one I trust the most.
I would generally agree with this a strong password and SSH without keys has never gone sideways for me and over 15 years of having public Linux servers. but I also make sure to install all security updates on a regular basis on any server no matter what SSH configuration is.
Agreed ! Also it would make graphs pretty boring ;)
Defense in depth -- maybe I'm paranoid, but just because something is unlikely doesn't mean an extra layer of security isn't advantageous. Particularly when I already have a VPN, so there's little reason not to use it.
Plus, my logs are easily checked as a side effect.
To each their own ! Security is a complex topic which usually resolves to adjusting the "security/annoyance" cursor to the best position.
In my case the constraints of using a VPN simply outweighs the security benefits.