this post was submitted on 24 Aug 2024
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How could simulating the ports as open be useful? (sopuli.xyz)
submitted 2 months ago* (last edited 2 months ago) by sapporo@sopuli.xyz to c/programming@programming.dev
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I've read an article which describes how to simulate the close ports as open in Linux by eBPF. That is, an outside port scanner, malicious actor, will get tricked to observe that some ports, or all of them, are open, whereas in reality they'll be closed.

How could this be useful for the owner of a server? Wouldn't it be better to pretend otherwise: open port -> closed?

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[–] sapporo@sopuli.xyz 1 points 2 months ago* (last edited 2 months ago) (1 children)

Ok, back to this then:

If everything reports open then what ports do you focus on first?

I don't see an issue here. An attacker would be overwhemed with choise and excitement so that he wouldn't be able to decide which port to choose first, get stuck for a several months unable to decide? He'd toss a coin then.

[–] nous@programming.dev 1 points 2 months ago (1 children)

Its costs him time - which is the point. They would have to do more detailed checks on every port which costs them time. Attackers are typically scanning loads of ports over large ranges of IPs, any small slow down on each can drastically slow down their overall progress making the attack less feasible and more expensive to undertake.

[–] sapporo@sopuli.xyz 1 points 2 months ago (1 children)

but an attacker isn't obliged to take on all the open ports, he could work with some of them - the ones that may seem the most interesting to him

[–] nous@programming.dev 1 points 2 months ago

Yes, which limits the amount of ports they can search and thus can be used to hide things on less popular ports. It is not going to stop an attacker. Just makes their job a bit harder or less complete.