Endlessh: An SSH Tarpit

Tangent story. Two friends of mine went backpacking to Amsterdam, short pants and all. When they got out of the train in the evening, a friendly guy approached them and asked if they were looking for a hotel. They said yes, so he told them to follow him. Delighted to be greeted in this way, they did.

First they went down the regular path up Damrak to get to Leidseplein, but slowly and imperceptibly the streets were getting narrower and narrower, until they finally reached a dead end. That's when the guy whirled around, flipped out a small pocket knife and wheezed to them, "Gimme all your cash! NOW!"

The guys looked at each other, and then looked at him, and then one of the guys calmly told him, "Look, we're two guys, and you're just one. Even if you get one of us, the other will beat your head in. You can't win this."

The mugger looked puzzled for a moment, but then he retorted, "Ok, give me half your money then, and nobody gets hurt!" Not wanting to be the first guy who got stabbed, they agreed that, "Fine, we'll give you half! But only if you promise to not stab us." And so the deal went down, and they had finally arrived in Amsterdam.

well what they're saying is sure you can do this but this hypothetical bike thief isn't going to follow you very far. ime this would seem to be the case. most ssh spam is very dumb, just looking for low hanging fruit w/ default credentials, and will likely move on very quickly without success.

It sounds like you’re both trapped in this scenario.

I had a similar issue, attempts to brute my server every minute of every day. I aggregated stats on the IP’s, basically every single one was Chinese. I blocked most of China’s IP ranges and it’s now as quite as it was in 2005.

This is why folks use techniques like greylisting and why you should almost never use a catch-all mailbox.

Spamhaus usually stops a big chunk of them too.

Something like:

  if(IP==attackerIP) {
    for 10000 times
       write random byte
       sleep 10 seconds
  }

If your passing through a NAT, you can whitelist your own IP.

something like: fail2ban-client set addignoreip x.x.x.x or fail2ban-client set addignoreregex hostname.com

True, but having supported an sftp server for other b2b clients to upload data, ssh keys are black magic to too many people. I can't count the hours I've spent trying to explain them, how to generate them and why you should never "show anyone your privates", just your publics.

Just an obvious protip to test that your cert works before banning password auths. I uh, found out the hard way.

Yeah, this is what I had in mind. Right now the economics there seem in favor of attackers since botnet resources for low level DDOS are plentiful. While major players have plenty of measures for mitigation, for a residential/SOHO/SMB/smaller NPO even a very cheap DDOS or actual more focused (but still automated) hunt for vulnerabilities and unpatched targets might cause real trouble. Economics works both ways unfortunately, efforts like tarpits in principle aim to make mass scans more expensive and troublesome reducing the incentives. But attackers in turn can work to make it more expensive and troublesome to run tarpits or the like, and certainly have incentive to see them not spread. So who has the best multipliers and resources?

If "we" (both the overall world community and subsections) were able significantly reduce the resources available to attackers for DDOS making vengeance/example setting more expensive that'd help. But it seems like it's going the other way if anything :(

You know this but I'm just throwing it in for people who don't and aren't working on large company things:

You can give yourself a WireGuard-powered, Single Sign-on, secure overlay network between, say, your phone, your laptop, a DO droplet and an AWS instance near-instantly and for (currently) free with tailscale.

By 'near-instantly' I mean it takes almost no effort to set up. It takes me longer to get my dotfiles right on a new host.

Explaining, since you were downvoted without a proper reason:

While everything is possible, most exploits happen on buffer overflows on user-received custom data. and since this is not allocating any buffer to receive anything (besides internal connection structures that are filled by the OS), the attack/exploit surface on this one is really tiny, if existent at all.

Crucially, endlessh has a smaller codebase than some shell scripts I've written. If you have ever used any program written with even a single line of Python, you have more to worry about than a 843 line program that appends a string to a socket.

Looks like it's been done: https://news.ycombinator.com/item?id=24494871