PUBLIC MARKS with tag knockd

A basic port knocker client for Android. Similar to the other port knocker apps but with a nicer interface. Includes a widget and the ability to choose an application to launch after knocking. The media/storage permission is needed for the import/export feature which allows you to save your list of hosts and then load them later.

knockd is a port-knock server. It listens to all traffic on an ethernet (or PPP) interface, looking for special "knock" sequences of port-hits. A client makes these port-hits by sending a TCP (or UDP) packet to a port on the server. This port need not be open -- since knockd listens at the link-layer level, it sees all traffic even if it's destined for a closed port. When the server detects a specific sequence of port-hits, it runs a command defined in its configuration file. This can be used to open up holes in a firewall for quick access.