Set ALPN to `ssh` if client sends SSH Magic Bytes

[coolaj86]

Set alpn to ssh if the first bytes from the client are 53 53 48 2d 32 2e 30 (SSH-2.0)

How to Find the Magic Bytes

nc -l localhost 2222 | hexyl

ssh localhost -p 2222 -o ConnectTimeout=1s

┌────────┬─────────────────────────┬─────────────────────────┬────────┬────────┐
│00000000│ 53 53 48 2d 32 2e 30 2d ┊ 4f 70 65 6e 53 53 48 5f │SSH-2.0-┊OpenSSH_│
│00000010│ 39 2e 36 0d 0a          ┊                         │9.6__   ┊        │
└────────┴─────────────────────────┴─────────────────────────┴────────┴────────┘