Computers are connected in a network to exchange information or resources with each other. Two or more computer are connected through network media called computer media. There are a number of network devices or media that are involved to form computer network. Computer loaded with Linux Operation System can also be a part of network whether it is a small or large network by multitasking and multi user natures. Maintaining of system and network up and running is a task of System / Network Administrator’s job. In this article we are going to review frequently used network configuration and troubleshoot commands in Linux.

1. By : Varnnit Jain
9990888972
Networking In Linux

2. Introduction
 Computers are connected in a network to exchange
information or resources with each other. Two or more
computer are connected through network media
called computer media.
 There are a number of network devices or media that
are involved to form computer network.
 Computer loaded with Linux Operation System can
also be a part of network whether it is a small or large
network by multitasking and multi user natures.
 Maintaining of system and network up and running is
a task of System / Network Administrator’s job. In this
article we are going to review frequently used network
configuration and troubleshoot commands in Linux.

3. Network Interface Names
 The linux kernel names interface with a specific
prefix depending on the type of interface.
 For Example : all Ethernet interfaces start with
eth, regardless of the specific hardware vendor.
Following the prefix, each interface is numbered,
starting at zero.
 etho, eth1 and eth2 would refer to the first,
second and third Ethernet interfaces.
 Other interfaces include wlan0 for the first
wireless device, virbr0 for the internal bridge set
up for virtual hosts, bond0 for the first bonded
network device, and so on.

4. Network Configuration and
Troubleshooting
 To check IP address of the system
#ip a
#ip ad
#ip add

5. Network Configuration and
Troubleshooting (Cont.)
 Network and IP configuration settings
#system-config-network
#system-config-network-tui

6. Network Configuration and
Troubleshooting (Cont.)
 To start network manually
#service network start
 To restart network configuration
#service network restart

7. Network Configuration and
Troubleshooting (Cont.)
 To keep network settings on when system
restarts
#chkconfig network on
 For checking connectivity between systems.
#ping (IP address)

8. Network Configuration and
Troubleshooting (Cont.)
 To disable NIC card/Interface (Here eth0)
#ifdown eth0
 To enable NIC card/Interface (Here eth0)
#ifup eth0

9. Network Configuration and
Troubleshooting (Cont.)
 To check the hostname
#hostname
 To change the hostname
#hostname new_name

10. Configuration on System
 Network configuration in GUI mode.
#system-config-network
 Firewall configuration in GUI mode.
#system-config-firewall
 Date and time configuration in GUI mode.
#system-config-date
 To setup different settings of the system.
(complete setup console in GUI mode).
#setup
 To check system IP configuration
#ifconfig (same as ipconfig in windows)

11. Scenario
 We have two systems. One with IP 10.0.0.1 and
another with IP 10.0.0.2 . We have to setup
network between both of these systems in order
to ping them to each other.
 Step 1 : Enable the interface of the first system.

12.  Step 2 : Set IP 10.0.0.1 to the ethernet 0 of the
first system.
using #system-config-network

13. Step 3 : Select the device you want to configure.
(Here we will chose eth0).

14. Step 4 : Network configuration window appears on the
Fill in the required blanks

15. Step 5 : Set the IP 10.0.0.1

16. Step 6 : Enable the Interface eth0 using #ifupeth0
Check the IP configuration of the same port using #ifc
IP for the first system has been set successfully.

17. Repeat the steps for the second system.
Set IP 10.0.0.2

18. The network has been set between both the systems.
You can simply check the connectivity between the two
Use the command ping 10.0.0.2 from first PC and see t