6 ms·
> Spoofing TCP is useless... See: https://en.wikipedia.org/wiki/TCP_sequence_prediction_attack https://en.wikipedia.org/wiki/TCP_sequence_prediction_attack It
by EvanAnderson 2y ago
> Spoofing TCP is useless...
See: https://en.wikipedia.org/wiki/TCP_sequence_prediction_attack https://en.wikipedia.org/wiki/TCP_sequence_prediction_attack
It's not practical but it is possible. It was more effective in the past when operating systems had more predictable initial sequence numbers. Famously this is how Kevin Mitnick (allegedly?) attacked Tsutomu Shimomura.
- beagle3 2y agoIt’s been more than 20 years since any mainstream operating system was vulnerable. IIRC even SYN cookies are older than 20 years at this point.
- o11c 2y agoIt is absolutely still a vulnerability; there's no way to protect yourself against someone who can read the sequence numbers anywhere in the middle of the network. Crypto can help you detect this but not prevent it. RST attacks in particular are common enough to make TCP completely unsuitable for reliable long-term connections. And since TCP is also unsuitable for short-term connections, that leaves UDP the only option.
- beagle3 2y agoWhich is exactly what I said two posts up. https://news.ycombinator.com/item?id=41329065 https://news.ycombinator.com/item?id=41329065 Now, RST attacks are still a thing, but mostly irrelevant to this port knocking alternative.