Knocker, a knock based access control system for your homelab

Fail2ban is not in the same realm as port knocking, and to "bin it" would be foolish security posture at best, and negligent at worst.

Every door you close, is one less someone can break.

Every complex services running, is a door someone can potentially break. Even with the most secure and battle tested service, you never know where someone fucked up and introduced an exploit or backdoor. Happened too often to be not a concern. XZ Utils backdoor for example was just last year.

> Your network authentication should not be a fun game or series of Rube Goldberg contraptions.

If there is no harm, who cares...

I mostly agree.. there’s a couple of very specific scenarios where maybe something like knockd makes sense I think but they are all scenarios where you’re doing things covertly, not as a general authentication mechanism.

As a side note I just happen to be reading a book at the moment that contains a fairly detailed walkthrough of the procedure required to access the Russian SVRs headquarters in New York in 1995.

Think of this as an analogue version and in no way a perfect analogy but it does include a step that has more or less the same security properties as this… anyways here’s a relevant quote:

“After an SVR officer passed through various checkpoints in the mission’s lower floors, he would take an elevator or stairs to an eighth-floor lobby that had two steel doors. Neither had any identifying signs.

One was used by the SVR, the other by the GRU. The SVR’s door had a brass plate and knob, but there was no keyhole. To open the door, the head of the screw in the lower right corner of the brass plate had to be touched with a metal object, such as a wedding ring or a coin.

The metal would connect the screw to the brass plate, completing an electrical circuit that would snap open the door’s bolt lock and sometimes shock the person holding the coin.The door opened into a small cloakroom. No jackets or suit coats were allowed inside the rezidentura because they could be used to conceal documents and hide miniature cameras.

SVR officers left their coats, cell phones, portable computers, and all other electronic devices in lockers. A camera videotaped everyone who entered the cloakroom. It was added after several officers discovered someone had stolen money from wallets left in jackets. Another solid steel door with a numeric lock that required a four-digit code to open led from the cloakroom into the rezidentura.

A male secretary sat near the door and kept track of who entered, exited, and at what times. A hallway to the left led to the main corridor, which was ninety feet long and had offices along either side. ”

Excerpt from Comrade J by Pete Earley

As another funny side note… I once discovered years ago that the North Koreans had a facility like this that they used to run a bunch of financing intelligence operations using drugs in Singapore where I was at the time and thought it would be funny to go and visit. It was in a business complex rather than a dedicated diplomatic facility from memory. But as I recall it was a similar scenario of unmarked door with no keyhole.

I guess at least they're being honest, but I would agree - there's a large delta between Al-assistance and Al-driven, and "vibe coding" is one step further (just accepting everything Al does without critique, so long as it "works").

Great for prototyping, really bad for exposing anything of any value to the internet.

(Not Anti-Al, just pro-sensible)

I guess I have to implement the habit of checking such things, since I never assume such a possibility. I prefer this info to be at the top of the readme, though – much more information value than the logo that deceived me into thinking this is a mature project.

Regardless; what benefits this would have over Wireguard?

> If you're Anti-AI please don't use this.

I'm pro security. The gall to put something out there, pretend it being vibe coded is not a big deal and possibly exposing hundreds of people to security issues. Jesus.

It's open source. Audit it like you would any other service that exposed your homelab to the Internet. How do you know XYZ repo isn't coded for some bootcampers capstone project? I bet those are even less secure.

Edit: should have mentioned I am a bootcamp grad, not just throwing random shade.

It could be fun extra layer. Like of course you should always use VPN, but maybe a magic packet so your VPN server even opens a port could be fun.

It shouldn't be your only layer of security, and then it's not important. Think of it as replacing explicit IP black/whitelisting - you still want a login wall or something, but now you restrict access to guess logins or otherwise obtain access through app vulnerabilities etc.

It’s the third option: Port knocking is stupid.

<https://news.ycombinator.com/item?id=39898061>

> How do you avoid this

IPv6 of course.

> or is it just not important

Port knocking not a security feature anyway.

If you're getting people to rely on external dependency services, e.g. Cloudflare or Tailscale, then you're a part of the problem, not the solution!

> IP based exclusion should not be considered a security measure

Apologies in advance if I'm missing something obvious here, but are you saying an IP allow list is not a standard security practice? If so I'd appreciate further explanation.

If you're running a homelab, the likelihood that you're interested in removing cloud-dependencies from your stack is above average. If that's the case, Tailscale is out.

Tailscale is just an added unnecessary external dependency layer (& security attack surface) on top of vanilla Wireguard. And in 2025 it's easier to run vanilla Wireguard than it's ever been.

There's nothing "hacky" about port knocking. It was never meant to be a complete security solution—nothing is.

But it works very well as an additional layer of security. Sec nerds often scoff at "security through obscurity", but it is a very valid strategy. Running sshd on a random high port is not inherently more secure, but it avoids the vast majority of dumb scanners that spam port 22, which is why all my systems do that. Camouflage is underrated, yet wildly effective. You can see how well it works in nature.

In any case, this is not a port knocking solution anyway, as I mentioned in another comment.