ifconfig

The above command will show all active interface of the machine and also give the information of

1. IP address assign to interface
2. MAC address of the interface
3. Broadcast address
4. Transmit and Receive bytes

Some example

ifconfig -a

The above command also show the disable interface

ifconfig eth0

The above command will only show the eth0 interface

ifconfig eth0 192.168.1.100 netmask 255.255.255.0

The above command will assign the static IP to eth0 interface

ifup eth0

The above command will enable the eth0 interface

ifdown eth0

The below command will disable the eth0 interface

ping

The above command (Packet Internet Grouper) is to test the connectivity between the two nodes

ping -c2 8.8.8.8

The above command will ping or test the connectivity with google server for 2 seconds.

traceroute

The above command is to use in troubleshooting to find out the number of hops taken to reach the destination.

netstat

The above command (Network statistics) give the connection info and their state

dig www.google.com

The above command (domain information grouper) query the DNS related information

nslookup www.google.com

The above command query the DNS and find out the IP address of corresponding the website name.

route

The above command is used to check the Netwrok route information. It basically show you the routing table

router add default gw 192.168.1.1 eth0

The above command will add the default route of network of eth0 Interface to 192.168.1.1 in routing table.

route del default

The above command will delete the default route from the routing table