As a side note, don’t be cute and pick port 221 or 2222 or 22022 or whatever that’s got “22” in it.

I know that sounds silly but the slightly less stupid bots are written by people who understand people do things like that and account for them, and thus port 2222 isn’t actually better than 22, or whatever.

Thanks! I did mention this briefly, although I belong to the school that “since I am anyway banning IPs that fail authentication a few times, it’s not worth changing the port”. I think that it’s a valid thing especially if you ingest logs somewhere, but if you do don’t choose 2222! I have added a link to shodan in the post, which shows that almost everybody who changes port, changes to 2222!

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There is one neat trick: don’t expose SSH.

There is still not a reason anyone has been able to give for 99% of self-hosters to expose SSH.

If you need to access your machine via ssh while on the go. Wireguard to your local network, use SSH. Done. Unless you are running an always-up public facing site, the amount of times you have to access your machine that can’t wait until after work is very low anyway.

Bots will scan all ports. That is just how it works. Less than 22, but you will still get spammed. Why force your computer to go through the fail2ban loop and take up resources when it is simply not needed at all and you can block it on another machine?

Fair question. What I meant is that suggesting that would have made the whole post 10 lines long and not worth doing. So I avoided such suggestions that completely change the threat model.

It’s not useless to avoid a good security posture (although you might have concerns of a monopoly gatekeeping the internet, TLS traffic inspection privacy concerns etc.), on the contrary makes everything I have written about here redundant (+ provide more, like DDoS protection) as you are outsourcing the security controls.

It is bad for the open web and constantly asks you to verify you are human

That is basically the essence of this post too! Except crowdsec is used to do what fail2ban does + some light form of WAF (without spinning another machine - which is not strictly needed for a WAF, you can use owasp modsecurity-ready proxies).

AFAIK I know that SSH has MaxAuthTries and LoginGraceTime, but all it does is terminating the SSH session (I.e. slow down at most), it won’t block the IP via firewall or configuration.

Not sure if there is a recent feature that does the same.

Yeah, what I mean is that it’s useless using ports like 2222, that’s like the unofficial SSH port! Bots are generally harmless (once you move to key auth), and you get functional the same result with the automatic IP ban on failed auth, minus the bother to change client configurations to your custom port. Anyway, if someone does want cleaner logs, changing port works :)

Hey, the short answer is yes, you can.

I would elaborate a little more:

• First, you have the problem of sourcing the data. In essence, Crowdsec won’t be able to go and fetch those logs for you dynamically, but can go and take those logs from a file (you can do a dirty solution like a sidecar deployment) or from a stream. You can deploy crowdsec in multiple modes, and you can have many instances that talk to each other. You can also simply have some process tailing the pod logs and sending them to a file crowdsec has access to or serving them as a stream (see doc.crowdsec.net/docs/data_sources/intro).
• The above means that it doesn’t really matter whether you run Crowdsec inside your cluster (it does have a Helm chart) or on the host. Ultimately all it matters is that crowdsec has access to your pods logs (for example, the logs of your ingress controller).
• The next piece is the remediation component. What do you want crowdsec to do, once it is able to detect bad IPs? If you want to just add IPs to the firewall, then it might make more sense running it on the host(s) you use in ingress, if you want to add the IPs to network policies you can do it, but you need to develop your own remediation components. I am planning to write a remediation component that will add the IPs to Hetzner firewall, some other systems are already supported, but this would be a way to basically block the IPs outside your cluster. For nginx ingress controller there is already a pre-made remediation component .

In practice I personally would choose a simple setup where the interesting logs are just forwarded (in Syslog format for example) to a single crowdsec instance. If you have ingress from a single node, I’d go for running it on the host and banning via firewall, if you have multiple ingress nodes, then I would run it inside the cluster and ban via a loadBalancer/cloud firewall/whatever you have in front.

In essence, I would spend some time to think about your preferences, and it might take a little bit to make the setup clean, but I think you have plenty of flexibility to do what you prefer. Let me know if you want to bounce some more ideas!

Oh, it looks like! Something went wrong with Zola build and I must have not noticed. Thanks a lot for pinging me about that, I will fix it today!

EDIT: Fixed! That’s what you get when you forget to bump the Docker image version after you upgrade zola version locally with a breaking change in the config! :) Thanks for letting me know, it would have taken me a long time to see it was broken!