Firewall Knocking

[Tom]

For anyone with a Linux server, there's an application called fwknop (http://www.cipherdyne.org/fwknop/) that allows you to lock down your firewall and then use single packet authentication to open specific ports for a user defined time for the IP address the packet was sent from. As an example, my firewall blocks all SSH access but sending the SPA packet from my phone opens up port 22 for it's ip

The android app (https://play.google.com/store/apps/details?id=org.cipherdyne.fwknop2) now has NFC support so you can unlock your firewall by tapping your ring