A default gateway is the node that serves as a link between two computer networks , that is, it is the device that connects and directs data traffic between two or more networks.
This device, when connecting two Internet Protocol (IP) networks, will have:
- a private IP address : to identify yourself within the local network ( intranet ),
- a public IP address: to identify yourself within the external network ( extranet ).
Generally, in homes or offices, that device is the router and cable modem or modem – DSL , which connects the home or office local area network ( LAN ) with the Internet ( WAN ).
In companies, it is often a computer that directs data traffic between the LAN and the outside network, and usually also acts as a proxy server and firewall .Example
A network is made up of devices and a router :
- Address of the devices (usually computers, can also be printers, etc.):
192.168.4.1(LAN private IP address), to communicate with the local network.
- public IP address (WAN, Internet), to communicate with another network, usually assigned automatically by Dynamic Host Configuration Protocol (DHCP), although it can be set by the Internet service provider (ISP).
- Subnet mask:
IP addresses from
192.168.4.1to can be used
192.168.4.0The and addresses
192.168.4.255are reserved for special uses (network address and network broadcast address ).