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Steven Polley 2024-04-16 20:09:37 -06:00
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README.md
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@ -25,14 +25,13 @@ Most port-knocking implementations are susceptible to replay attacks, a network
hyp supports a clock skew of up to 30 seconds between client and server.
### TBD: Protection Against Sweeping Attacks
### Protection Against Sweeping Attacks
~~hyp protects against sweeping attacks where an adversary modulates over the entire port range multiple times by ensuring the authentic knock sequence is strict and ordered correctly. If the first port is guessed, but the next pack arrives and is the incorrect second port in the sequence, the progress gets reset.~~
hyp protects against sweeping attacks where an adversary modulates over the entire port range multiple times by ensuring the authentic knock sequence is strict and ordered correctly. If the first port is guessed, but the next pack arrives and is the incorrect second port in the sequence, the progress gets reset. In addition to this, the correct authentic knock sequence must be entered within 5 seconds of the start of the sequence.
### Known Weaknesses
* Lossy networks can result in the knock sequence failing
* Networks with latency > 500ms can result in the knock sequence failing if packets arrive out of order
### References

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hypd/server/README.md Normal file
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# hypd server
hypd is the port knocking daemon which runs on an edge device connecting to an untrusted network. Leveraging eBPF's XDP hook point, it extracts header information directly and sends to userspace the specific information required. This method is faster than alternative methods such as using libpcap.
### eBPF
The hyp_bpf.c program can be recompiled using go generate.
```bash
# Debian: sudo apt install git clang linux-headers-amd64 libbpf-dev
go generate .
```
### Generating vmlinux.h
vmlinux.h is included in hyp_bpf.c and can be regenerated with bpftool.
```bash
# Debian: sudo apt install bpftool
sudo bpftool btf dump file /sys/kernel/btf/vmlinux format c > ../headers/vmlinux.h
```
### Building hypd
hypd has no CGO dependencies and so can run on musl systems as well.
```bash
# To ensure it can run on systems don't use CGO
CGO_ENABLED=0 go build .
```