[SOLVED] Find which NIC plugged.

hack3rcon · 06-17-2017, 02:13 AM

Hello.
I installed CentOS 7 x64 on a system via 4 NIC, But just one NIC cable is connected. The DHCP server is not enabled too and I want to configure my NIC manually, But how can I find the name of NIC that cable plugged to it?

Thank you.

ferrari · 06-17-2017, 04:10 AM

You can get the link state for each device node present using the ip command...

Code:

ip link

aragorn2101 · 06-17-2017, 04:25 AM

Just to build up on what ferrari correctly advised, I'll post outputs for the ip command so that you see how you will identify the connected NIC.
I have only one NIC but you'll spot the difference easily.

When network cable is connected:

Code:

# ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether 3c:xx:xx:xx:xx:49 brd ff:ff:ff:ff:ff:ff

When network cable is disconnected:

Code:

# ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT qlen 1000
    link/ether 3c:xx:xx:xx:xx:49 brd ff:ff:ff:ff:ff:ff

Spot the NO-CARRIER and state DOWN?

hack3rcon · 06-17-2017, 06:18 AM

Thank you so much.