Source code and details: https://github.com/umutcamliyurt/PortTripper
How it works
On startup PortTripper:
- Scans the configured port range and builds a whitelist of ports already in use by real services (first run only).
- Draws a cryptographically random sample of up to
-maxportsports from the range, excluding whitelisted ports. Usingcrypto/randfor selection means the open set is unpredictable to an attacker even if they know the configured range. - Binds TCP and UDP listeners on every chosen port.
- On TCP: accepts connections, holds them open for a configurable duration, then drops them, wasting the scanner’s threads and file descriptors.
- On UDP: reads and discards datagrams without replying, so ports appear
open|filteredto scanners rather thanclosed.
All real service ports are untouched because they are already bound before PortTripper starts, and the auto-generated whitelist tells PortTripper to skip them.
Also, unless I’m fundamentally misunderstanding the purpose of this… Wouldn’t this be completely irrelevant if you’re running a reverse proxy anyways? You only need to worry about port mapping if you’re running open ports. But ports 80 and 443 are reserved for http and https traffic, so they’re functionally useless for a potential attacker looking to map your running services.
Basically, this only “protects” you if you have open ports? Just don’t open ports to begin with. Use a reverse proxy.
The only way I can see this being useful is to protect against LAN traffic, not WAN. But if they’re able to get on your LAN, you’re probably already in the “unplug everything” stage of damage control. Other honeypots would be better equipped to alert you of the port sniffing on your LAN, instead of simply stalling an attacker by eating your own server’s resources.
You need to open ports to a reverse proxy?
My point was that this only really helps if they’re already on your LAN. Ports 80 and 443 (the ports your reverse proxy would use) are functionally useless for an attacker to map. And if they’re already on your LAN, there are honeypots that will do better than simply eating server resources to delay (not stop, just delay) an attacker.
I’m not sure you understand what a “honeypot” is. The entire point is to set it up somewhere public so that people try to scan and connect to it. It doesn’t protect anything. It’s designed to try to slow-down attackers who probe random systems.
I’m not sure you understand what a honeypot is. You only listed one kind, and it is arguably the most useless kind. I don’t care about what happens outside of my WAN, because that is what a firewall is for. I only care about what happens inside the firewall. A good honeypot will act as an early warning system for a breach. It is an attractive target for people who are looking to spread to other devices on the network.
If an attacker gets into your network, the honeypot is designed to act as an attractive target and alert you when it gets hit. I don’t care if people try to scan my WAN ports. Bots do that all the time. It’s basically a given. But with a reverse proxy, you’re only opening ports 80 and 443. Those are basically useless for an attacker, because it only tells them that you’re running something on http and https. And that could be anything.
If I’m running a honeypot, it’s going to be to alert me if something gets breached. It’s going to run on my LAN, not my WAN. If something on my LAN suddenly starts scanning all of my server’s ports, it’s because that thing is a rogue device/attacker. I’m not interested in stalling them. I want to be automatically alerted and to completely shut them out. That’s what a good honeypot will do. A bad honeypot just wastes time and resources, instead of alerting me to the potential breach.
That you seem to think a reverse proxy provides some sort of security is a bit… Terrifying.