Genkan is a real place in a real house. It is the bit of floor that is neither outside nor properly inside.
Walk into a Japanese home and you do not walk straight in. You step down into a small recessed space, take your street shoes off, leave them there, and step up onto the floor of the house. That space is the genkan (say it GEN-kan, hard g, like get). It is not a security measure and nobody is being searched. It is a boundary made of hospitality: come in, and leave what you have walked through today at the door.
The word is older than the hallway. It comes from the Chinese 玄關, the hidden gate. 玄 means dark, hidden, profound. 関 means barrier, or checkpoint, the same character used for the inspection posts on the old highways. It first meant the entrance to the guest quarters of a Zen monastery, the doorway onto the path, and only later did ordinary houses borrow it for the place the boots come off.
So for a thousand years the word has meant one thing. The gate where the outside stops.
Which is the whole idea here. Your internet connection brings the entire world into your house at once. Most of it is fine. Some of it is mud, and a good deal of it is engineered, by people paid extremely well to engineer it, to take as much of your kid's attention as it can get and give nothing back. This box is the step it all has to cross first. Leave the dirt in the genkan. It catches what you would rather not have tracked through the house.
It began as a switch to turn the wifi off.
The screens were winning. Not dramatically. Just the ordinary grind.
Three kids, eleven, fourteen and sixteen. The endless scroll, one more round, one more episode, and the same conversation every evening that ended with me physically walking over and taking a device out of somebody's hands. That is not parenting. That is refereeing, badly, seven nights a week.
I went looking for something to help and did not much like what I found. The good parental-control services want a subscription and, in return, a copy of everywhere your children go on the internet. The router apps are clumsy and treat a sixteen-year-old exactly like an eight-year-old. Almost all of it is built to watch children rather than to help them.
So the first version was tiny. One command, on my own hardware, that turned the kids' internet off. That is genuinely all it was, and it was already better than what I had, because the boundary stopped being me standing in a doorway and started being a thing everybody could see.
Every parent knows the fight. The screens win because the tools are built for the platforms, not for you.
Router apps are clumsy. The good parental-control services want a subscription and a copy of everywhere your kids go. Genkan takes the other road: it sits between your kids' devices and the internet as a gateway you own outright, so turning gaming off, holding dinner, or handing over thirty earned minutes is one sentence to an assistant you talk to from your phone.
And once a box like that exists, it may as well look after the rest of the house. The same gateway that meters Roblox is the one that decides your security camera may talk to its own maker and to absolutely nothing else. Parental controls and a household firewall turn out to be the same machine, which is why Genkan is both.
One warm box by the router, and the whole house gets a little calmer.
You are not up against your kid. You are up against a thousand engineers.
The feed is not badly made. It is superbly made, for a goal that is not your child's. Watch time is ad inventory, so autoplay, streaks, notifications and the scroll that never bottoms out all point one way: keep going, do not stop, do not go outside.
This is not a war on screens, and it is certainly not a war on your children. Screens are where their friends are, where their music is, and increasingly where their homework is. The thing worth pushing back on is narrower than that: the deliberate engineering of the bit where four hours vanish and nobody chose it.
So Genkan does not just take time away, it changes what time costs. Music is free and always was. Schoolwork is free. Messaging a parent is free. Gaming and video are the two things on the clock, and when that clock runs out a kid can earn more by learning something rather than by pleading. Effort buys minutes. Nagging does not.
Under the bonnetHow the box is actually put together
A Docker container owns its own network namespace with exactly two interfaces: the uplink, and the USB network card the kids' access point plugs into. The firewall (nftables), the DHCP and DNS server (AdGuard Home) and the children's portal all live inside that namespace, so they physically cannot reach the host, the rest of your home network or your VPN. Not "are configured not to". Cannot.
Postgres holds the desired state. The gateway rebuilds the firewall from it every fifteen seconds, which is why a phone plugged in at 9pm is covered by 9:00:15pm and why a reboot cannot forget that somebody is out of time. The parent dashboard runs on the host, outside the island, so the thing you control it with is not on the network it controls.
Evening the odds, not winning an argument. A parent competing with a global attention business, alone, on willpower, at 9pm, is outgunned. That is not a parenting failure, it is a mismatch. Genkan is simply a bit of the same engineering pointed back the other way, on your side of the wall, working for your house rules.
Every answer suggested the next question.
None of that was a plan. It is just what happens when the box in the hallway turns out to be the right place to solve the next problem too. It started as a way to stop dragging teenagers off devices, and it ended up as the household's own gateway.
Three decisions that have not moved.
What this is, and what it is not.
A boundary you set once that holds on its own, so the clock is the clock and not you.
A way to read your children's messages. It cannot, and it is not built to.
Transparent with kids. It tells them the network is filtered and shows them exactly what it can and cannot see.
Unbeatable. A determined teenager with mobile data has simply left your network, and the answer to that is a conversation.
Honest about the half-built parts. The roadmap marks nothing as done unless you can run it today.
A company. One parent built it, then opened it up. There is nobody here looking for a return.
Why give it away? Because I am not the only parent having this argument, and because the thing that makes it trustworthy is the thing that makes it free. You can read every line, run it on your own hardware, and point your own AI at it and ask whether it is telling you the truth. That only works if it belongs to you.