SINGLE PACKET AUTHORIZATION (PORT KNOCKING) EXAMPLE SIMULATION IN MININET
SPA is one method of port knocking used to dynamically modify firewall rules and allow access to specific port of a remote system. Details on this may be read from https://en.wikipedia.org/wiki/Port_knocking . We will be implementing a network with SPA authorization for SSH. Here the system is configured to allow access to SSH port (number 22) only after receiving an authorization packet from a remote system. The authorization packet used is TCP SYN packet with ISN(2361294848) and TOS(3). Upon receipt of this packet the access to SSH port is enabled for 60 seconds. SSH connection is allowed to the system for this duration window only. If remote system establises a connection using ssh within this duration, then the connection persists. Here, two methods to allow SPA are discussed. First one allows port opening for a particular IP address and second method uses the MAC address of requesting system to authenticate opening of port. The second method is useful when DHCP is configured to ...