Detecting Multiple Ethernet Cards in Linux

When a Linux machine has more than one network card, the first step is to confirm that the kernel can see each device.

List network interfaces

ip link show

This shows interfaces such as eth0, eth1, ens33 or enp0s3, depending on the Linux distribution and naming scheme.

lspci | grep -i ethernet
lspci | grep -i network

dmesg | grep -i eth

If a card is visible in lspci but not in ip link, the likely issue is a missing or unloaded driver.