Everything to check information about the hardware by commands your linux system, the following commands will get network inteface, which IP address configured to specific interface (like, eth0, eth1 and etc...).

ipconfig

This command used to configure network interface, if you run the command without arguments show the status of the currently active interfaces.

-a argument is given displays the status of all interfaces even shows down the interface.
 

# ifconfig

# ifconfig -a


eth0      Link encap:Ethernet  HWaddr 00:A9:23:19:AA:AB

          inet addr:192.168.0.210  Bcast:192.168.0.255  Mask:255.255.255.0

          inet6 addr: fe80::219:21ff:fe29:abb/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:28378 errors:0 dropped:0 overruns:0 frame:0

          TX packets:23062 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:18844580 (17.9 MiB)  TX bytes:2919482 (2.7 MiB)



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:65536  Metric:1

          RX packets:2440 errors:0 dropped:0 overruns:0 frame:0

          TX packets:2440 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:459932 (449.1 KiB)  TX bytes:459932 (449.1 KiB)


ip command:

IP Command is used to show / manupulate routing, devices, policy routing and tunnels for networks, the following commands shows details.
 
#  ip route show


192.168.0.0/24 dev eth0  proto kernel  scope link  src 172.17.42.1

169.254.0.0/16 dev eth0  scope link  metric 1002

default via 192.168.0.1 dev eth0


To dispalys only active ethernet interface
 
# ip link show | grep 'state UP'
2: eth0: mtu 1500 qdisc pfifo_fast state UP qlen 1000


The below command help you find Device Name only,
 
# ip link show | grep 'state UP' | awk '{print $2}' | cut -d ':' -f1
eth0


netstat command:

Previously have been discussed about netstat command, below command show with kernel interface table format,
 
# netstat -i


Kernel Interface table

Iface       MTU Met    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg



eth0       1500   0   336634      0      0      0   119985      0      0      0 BMRU

lo        65536   0     7536      0      0      0     7536      0      0      0 LRU


Enable / Disable Network Interface :

By default the network interface detected on your system if you are trying to configure manually enabled it ifup command and to disable  ifdown command will help you. Assume that if you have configure eth1 enterface execute below command enable it.
 
# ifup eth1

Disable interface,
 
# ifdown eth1