knock

To run:

go run main.go

Once started you'll see the sequence. You can use something like netcat to trigger the sequence.

nc -u 127.0.0.1 <portnumber>

Here is how to do 3 knocks in sequence (arr is the knock port sequence):

arr=(38752 39259 31959); for i in "${arr[@]}"; do echo "ping" | nc -u -w0 127.0.0.1 $i; done

Once you have knocked successfully you should be able to get to http://localhost:9999.

Future ideas:

• Use something like TOTP to generate the ports.
• Perhaps use an IP address to index by, since the list is global.
• Allow the webserver to be accessed only the IP that knocked it.
• Disconnect the webserver after a period of time