Networking related Linux Basic commands

Networking related Linux commands

Networking:

It is a connection between two or more machines to communicate with each other.

The basic requirements for networking are:

• NIC (Network interface Controller or Card)
• Media
• Topology
• Protocol
• IP Addresses

Now we will see networking related Linux commands are as fallows.

How To check the IP address assign to all the interfaces

#ifconfig

[root@rahul ~]# ifconfig eth0      Link encap:Ethernet  HWaddr 08:00:27:0A:86:5B           inet addr:192.168.10.10  Bcast:192.168.10.255  Mask:255.255.255.0           inet6 addr: fe80::a00:27ff:fe0a:865b/64 Scope:Link           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:6 errors:0 dropped:0 overruns:0 frame:0           TX packets:19 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000           RX bytes:660 (660.0 b)  TX bytes:3368 (3.2 KiB) lo        Link encap:Local Loopback           inet addr:127.0.0.1  Mask:255.0.0.0           inet6 addr: ::1/128 Scope:Host           UP LOOPBACK RUNNING  MTU:16436  Metric:1           RX packets:248 errors:0 dropped:0 overruns:0 frame:0           TX packets:248 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:0           RX bytes:23534 (22.9 KiB)  TX bytes:23534 (22.9 KiB) [root@rahul ~]#

How to Check the ip of a particular interface

#ifconfig < adapter name >

#ifconfig eth0

[root@rahul ~]# ifconfig eth0 eth0      Link encap:Ethernet  HWaddr 08:00:27:0A:86:5B           inet addr:192.168.10.10  Bcast:192.168.10.255  Mask:255.255.255.0           inet6 addr: fe80::a00:27ff:fe0a:865b/64 Scope:Link           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:6 errors:0 dropped:0 overruns:0 frame:0           TX packets:23 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000           RX bytes:660 (660.0 b)  TX bytes:4218 (4.1 KiB)

How to check hostname of the system

#hostname

[root@linuxelearn ~]# hostname Linuxelearn.rj.com

How to check IP of the host

#hostname –i

[root@rahul ~]# hostname -i 10.0.2.4 127.0.0.1

How to check whether DNS is resolving or not ?

#host < ip address >

#host 192.168.10.10

[root@linuxelearn ~]# host 192.168.10.10 10.10.168.192.in-addr.arpa domain name pointer linuxelearn.rj.com.

#host <hostname>

#host linuxelearn.rj.com

[root@linuxelearn ~]# host linuxelearn linuxelearn.rj.com has address 192.168.10.10

How to change the hostname of machine ?

Check the current hostname with hostname command

The syntax for changing the hostname is

#hostname < new name >

#hostname linuxelearn.rj.com

[root@linuxelearn ~]# hostname linuxelearn.rj.com [root@rahul ~]# hostname rahul.rj.com

Note:  The above change is temporary and will be last only till you are logged in, if you want to change it permanently edit the /etc/sysconfig/network file and then logout and login to confirm the change.

            #vim /etc/sysconfig/network delete the previous hostname and add the new name.

[root@rahul ~]# vim /etc/sysconfig/network

NETWORKING=yes HOSTNAME=linuxelearn.rj.com ~ ~

• Now logoff and logon and check the hostname

[root@linuxelearn ~]# hostname linuxelearn.rj.com  [root@rahul ~]#

Note: Once you logout and login the change will be permanent, observe the highlighted region above.