Port Knocking Sequence Generator

Port knocking keeps a port closed until an agreed sequence of connection attempts arrives on closed ports. The server watches those attempts, recognises the sequence and opens the real port briefly for that address. Anyone running a scan sees everything closed — there is no service listening to answer.

Choose how many ports and which protocol, and the page draws the sequence. Two implementation decisions matter: the ports come from the high range, above the registered ones, so they do not collide with a real service; and the draw uses the browser's cryptographic generator, including for the choice between protocols when mixing is selected — the sequence is the secret, and a secret drawn with a weak generator is a predictable secret.

On what this protects: it is obscurity, not authentication. Anyone watching network traffic sees the sequence and can repeat it. The real value is removing the service from the view of automated scanning, which cuts brute-force noise to nearly zero, and serving as an extra layer over genuine authentication — never in place of it.