#How_Do_I_Find_Out_Linux_Gateway / #Router_IP_Address?

How do I find out my #gateway IP for a #computer or a #network device that allows or controls access to another computer or network under #Linux / #UNIX operating systems?
The ansver is almost simple for unix users...

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.

You need to use route command. Open an Terminal and type this command will show you #IP_routing_tables. It can be also use to print gateway / router IP address. Type the following command to see #default_gateway:

$ route -n

Output:

Kernel IP routing table
Destination    Gateway       Genmask           Flags   Metric   Ref   Use   Iface
0.0.0.0           192.168.1.1   0.0.0.0               UG     100         0      0       enp5s0
192.168.1.0   0.0.0.0           255.255.255.0   U        100         0      0       enp5s0

192.168.1.1 is gateway IP address for our computer.

The flag:
U indicates that route is up
G indicates that it is gateway.

Static IP or DHCP Configuration on Ubuntu / Debian

How to configure Ubuntu Linux with
static or dynamic (dhcp) IP
by morphus.dk

File: /etc/network/interfaces

Static IP example:

auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 208.88.34.106 netmask 255.255.255.248 broadcast 208.88.34.111 network 208.88.34.104 gateway 208.88.34.110

Dynamic IP (DHCP) example:

auto lo iface lo inet loopback auto eth0 iface eth0 inet dhcp auto eth1 iface eth1 inet dhcp auto eth2 iface eth2 inet dhcp auto ath0 iface ath0 inet dhcp auto wlan0 iface wlan0 inet dhcp

Interfaces:

• lo: Loopback interface (network within your system without slowing down for the real ethernet based network)
• eth0: First ethernet interface card
• wlan0: First wireless network interface

Also see "man interfaces"