There has been a report that certain devices (IoT, modems, BMCs, routers, switches, remote management) that use proprietary implementation of SSH instead of OpenSSH are vulnerable to private key exposure/compromise.
this post was submitted on 19 Nov 2023
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It's bots trying to brute force your SSH login. It happens all the time.
Just change SSH to key based only (disable password login) and move on.
This is completely normal for a machine exposed to the internet. In the words of Obi Wan, "Nothing to see here, move along ..."
This happens literally all the time for me both personally and professionally. I see mostly low effort attempts across various ports or things like sweeps of common username/password attempts on ssh or common management endpoints on http.
This is why it's important to keep all publicly accessible servers and services updated and follow standard security guidelines. Things like only using public key auth for ssh for instance.
At work we get hit occasionally in large bursts and have to ban ips for a bit to get them to go away.
Is it a good idea to have SSH open to the internet?
Yes there’s nothing wrong with it. SSH autt is robust.
As long as you're running fail2ban there's no harm in it. Without exception you should disable root login, and ideally you should disable password login and just use keys.
Fail2ban does all of nothing to protect you. At best it keeps the noise in the logs down a bit.
Competent attackers tend to use a botnet, blocking and rate limiting does jack shit against 10,000 IPs.
When I ran fail2ban, I modified the action to ban a much larger subnet instead of just one IP. I also banned it for 24 hours. Now I run OPNsense with geo blocking and just ignore the logs. It's just noise.
It's fine, but it's a good idea to disable password authentication and only permit public key auth. Using a non-standard port helps reduce the spam in the logs a bit.
This is normal background noise and nothing to worry about at all. Just be sure you’re using keypair login and user/password login is disabled.
Don't use port 22
If you have anything exposed to the internet, this is going to happen. Keep your stuff updated and button it up as much as possible.
Don’t use port 22 for ssh, and run something like endlessh on port 22.
Is there some program that lets anyone in and logs their activity?
They’re called love taps, the internet loves you ❤️
Ha, yeah this is very common.
I’ve been constantly under attack from about ten times this for around 10 years.
They brute force common words and try various names as logins. It’s very primitive.
It waxes and wanes in frequency but averages to three or four per minute.
I have ssh on port 2222 (which btw they also figure out pretty quickly, I would recommend a less obvious alternative port) and fail2ban catches them after a couple tries, but without fail new ips spin up and resume.
It’s futile. I don’t have password auth on. They’ll never get in.
It’s just like people walking down the street coming up to your door to see if it’s unlocked. Or trying car doors for the same. They can try all they want, they’re not getting in.
Moral of the story: yeah it feels scary, but it’s really not. Make sure you have password auth and root login turned off, and fail2ban is a good call. Otherwise ignore it, it’s just something that will always happen on the internet.
I once bound a /16 to a server. Dropped like a rock instantly over ssh attacks 😂 over 10,000/s
Could you dumb this down for the class, what do you mean by 'bound a /16'?
You're using standard ports so it'll happen constantly.
I moved all my ssh to nonstandard ports.
Bots will find it pretty quickly. Remember the first thing that happens when you connect to an SSH server is get a message saying “Hi, I’m an SSH server! How are you today?”.
Just set a custom port above 60000, and it’ll never get touched. Having SSH open on the WAN is wild though.. not sure why you’d do that.
If you need to access the server remotely and it needs to be WAN-facing, set up a VPN server
I use fail2ban too and set the ban limit to 48 hours. I regularly have around 1000 banned IPs
That‘s normal. There are countless bot nets that scan every public available IP to hijack. Using fail2ban is already a good approach. I personally switched to crowdsec a while ago as it comes with a crowdsourced blacklist which will silence a lot of the common noise and only occasionally I get an Alarm about an IP address not already on the default list.