System (S) for the routing of data to computer networks, comprising: - at least a server unit (SRV) connected to a public network (I); - at least a local area network (Prop. LAN 1, ... , Prop. LAN m) having at least a client device (CL1, ... , CLn); - at least a routing unit (FW1, ... , FWm) having a first network interface (eth0) connected to said public network (I) directly or indirectly through a local area network of third parties (3p LAN 1, ... , 3p LAN m) and having at least a second network interface (eth1) connected to said local area network (Prop. LAN 1, ... , Prop. LAN m); - wherein to said first network interface (eth0) is assigned a public IP address or a private IP address determined by said local area network of third parties (3p LAN 1, ..., 3p LAN m); - and wherein to said local area network (Prop. LAN 1, ... , Prop. LAN m) is assigned at least a predefined class of private IP addresses; characterized in that said routing unit (FW1, ... , FWm) comprises automatic routing means (VMO) of data between said at least one server unit (SRV) and said at least one local area network (Prop. LAN 1, ... , Prop. LAN m) independently of the IP address assigned to said first network interface (eth0), provided with at least a first virtual network interface (eth0') connected to said first network interface (eth0), with at least a second virtual network interface (ethl') and with determination means (M) suitable for determining an IP address to be assigned to said second virtual network interface (ethl') according to said IP address of the first virtual network interface (eth0'), so that: - said IP address of the second virtual network interface (ethl') belongs to a class of IP addresses different to the class of IP addresses of said IP address of the first virtual network interface (eth0'); - said IP address of the second virtual network interface (ethl') does not coincide with any of the IP addresses assignable to said local area network (Prop. LAN 1, ... , Prop. LAN m). - at least a server unit (SRV) connected to a public network (I); - at least a local area network (Prop. LAN 1, ... , Prop. LAN m) having at least a client device (CL1, ... , CLn); - at least a routing unit (FW1, ... , FWm) having a first network interface (eth0) connected to said public network (I) directly or indirectly through a local area network of third parties (3p LAN 1, ... , 3p LAN m) and having at least a second network interface (eth1) connected to said local area network (Prop. LAN 1, ... , Prop. LAN m); - wherein to said first network interface (eth0) is assigned a public IP address or a private IP address determined by said local area network of third parties (3p LAN 1, ..., 3p LAN m); - and wherein to said local area network (Prop. LAN 1, ... , Prop. LAN m) is assigned at least a predefined class of private IP addresses; - said IP address of the second virtual network interface (ethl') belongs to a class of IP addresses different to the class of IP addresses of said IP address of the first virtual network interface (eth0'); - said IP address of the second virtual network interface (ethl') does not coincide with any of the IP addresses assignable to said local area network (Prop. LAN 1, ... , Prop. LAN m). <EOS>