A gateway is a network point that acts as an entrance to another network. On the Internet, a node or stopping point can be either a gateway node or a host (end-point) node. Both the computers of Internet users and the computers that serve pages to users are host nodes. The computers that control traffic within your company's network or at your local Internet service provider (ISP) are gateway nodes. In the network for an enterprise, a computer server acting as a gateway node is often also acting as a proxy server and a firewall server. A gateway is often associated with both a router, which knows where to direct a given packet of data that arrives at the gateway, and a switch, which furnishes the actual path in and out of the gateway for a given packet.
Find out Gateway / router IP address under Linux / UNIX using route command
You need to use route command. This command can manipulates the kernel’s IP routing tables. It can be also use to print gateway / router IP address. Type the following command to see default gateway:
$ route -n
Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 ra0 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 ra0
192.168.1.1 is gateway IP address for our computer. The flag U indicates that route is up and G indicates that it is gateway. You can print gateway name, enter:
Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 * 255.255.255.0 U 0 0 0 ra0 default wrt 0.0.0.0 UG 0 0 0 ra0
Second column prints Gateway hostname / IP address. In our example wrt is gateway.
netstat command example to find out gateway/router IP
Open a terminal and type the following command:
# netstat -r -n
Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 eth1 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1