You can configure a network interface from the command line using the basic Linux networking utilities. You configure your network client hosts with the command line by using commands to change your current settings or by editing a number of system files. Two commands, ifconfig and route, are used for network configuration. The netstat command displays information about the network connections.
ifconfig Advantages
ifconfig is used to configure your network interface. You can use it to
Activate or deactivate your NIC or change your NIC’s mode
Change your machine’s IP address, netmask, or broadcast address
Create an IP alias to allow more than one IP address on your NIC
Set a destination address for a point-to-point connection
Using ifconfig with Examples
If you want to find your current ip address you need to enter the following command
ifconfig
Output looks like below
eth0 Link encap:Ethernet HWaddr 00:0F:EA:B2:53:85
inet addr:192.168.2.5 Bcast:192.168.2.255 Mask:255.255.255.0
inet6 addr: fe80::20f:eaff:feb2:5385/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:471 errors:0 dropped:0 overruns:0 frame:0
TX packets:695 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:160637 (156.8 KiB) TX bytes:86193 (84.1 KiB)
Interrupt:185 Base address:0x6000
Create new network alias to a network card (NIC)
Syntax
ifconfig [network device]
Example
ifconfig eth0:1 172.30.49.4
Change IP address
ifconfig eth0 172.30.49.13
Change Subnetmask
Syntax
ifconfig netmask [netmask]
Example
ifconfig eth0 netmask 255.255.255.0
Change broadcast address
Syntax
ifconfig broadcast [address]
Example
ifconfig eth0 broadcast 172.30.49.1
Take interface down
Syntax
ifconfig [network device] down
Example
ifconfig eth0 down
Bring interface up
Syntax
ifconfig [network device] ipaddress up
Example
ifconfig eth0 172.30.49.13 up
If you want to know more information about ifconfig check man page
route command
route is used to build the routing tables (in memory) implemented for routing packets as well as displaying the routing information. It is used after ifconfig has initialized the interface. route is normally used to set up static routes to other networks via the gateway or to other hosts.
route Syntax
route [options] [commands] [parameters]
Examples
To display the routing table, use the route command with no options.
route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.2.0 * 255.255.255.0 U 0 0 0 eth0
default . 0.0.0.0 UG 0 0 0 eth0
Using the -n option to the route command will give the same information, substituting IP addresses for names and asterisks (*), and looks like this
route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth0
Add new route
route Syntax
route add default gw ipaddress interface
add a gateway with a specific IP address, you could use the following
route add default gw 172.30.49.1
If you want to know more information about route check man page
Hi,i was installed the debian Etch 4.0, and i have a problem with the “ifconfig” command.
when i’m use this command the line that i wrote below was shown:
Bash: ifconfig: command no found
please help me for this eror.
thanks for your help.
Hello,
You may need to be under root, to do so, type su and you’ll be asked for the password.
Hope it help
Cheers
if it still doesent work as root try this:
/sbin/ifconfig
you can also run this command un-rooted on most systems.
Hi;
Can someone please tell me how to use ifconfig to set address for eth0 from DHCP?
Thanks.
I forgot how to do it.
something like ifconfig eth0 inet dhcp ??
wont work!
And how to use 2 gateways in the same subnet (with or without failover or/and loadbalance).
i.e.
1. Router:
192.168.1.1
2. Router:
192.168.1.254
Debian-Server:
192.168.1.3
And how to use both gateways now on server?
Hi Matey
[Can someone please tell me how to use ifconfig to set address for eth0 from DHCP?]
Edit the file /etc/network/interfaces
# Your primary network interface
auto eth0
iface eth0 inet dhcp
Thank You very much Jaelson for the information.
Does anyone know what to do if I’m using a USB ethernet adapter?