Firewall system for interconnecting a first IP network (10) to a second IP network (16), these networks belonging to two different entities having each a different administration wherein any data packet transmitted/received by the first IP network is filtered by using a first firewall function and any data packet transmitted/received by the second IP network is filtered by using a second firewall function. The system comprises essentially a single firewall device (20) including filtering means (41, 43) performing both first firewall function and second firewall function, a console port (37) enabling the administrator in charge of each IP network to enter filtering rules for updating the associated firewall function and control means (39, 47, 49) interconnecting the console port and the filtering means for transmitting thereto the filtering rules so that each administrator may independently manage the system from the console port.