The ifconfig command gives different kinds of information about a network card. It first starts with the name of the protocol used on the network card. This is indicated with, for example, Link encap: Ethernet, which states that it is an Ethernet network board. Then, if applicable, the MAC address is mentioned as the HWaddr. This address is followed by first the IPv4-related address information and then the IPv6-related address information. Then several statistics about the network board are mentioned. Pay special attention to the RX packets (received packets) and TX packets (transmitted packets) entries; from these statistics you can see what the network board is doing and whether any errors have occurred while doing it. In addition to the information about the physical network boards that are present in your server, you will also always see information about the loopback device (lo). This is the network interface used for internal purposes on your server. You also need this loopback device because some services depend on it; for example, the graphical environment that is used on Linux is written on top of the IP stack offered by the loopback interface.
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