The Wired tab contains two configurable parameters: one for the MAC (Media Access Control) address, and another for the MTU (Maximum Transmission Unit) value:
Editing the System eth0 wired network connection
MAC Address
Network hardware such as a Network Interface Card (NIC) has a unique MAC (Media Access Control) address that identifies it to the system. Running the ifconfig command will show the MAC address associated with each interface: HWaddr 00:1C:25:14:4A:E0 for example.
MTU
The MTU (Maximum Transmission Unit) value represents the size in bytes of the largest packet that the connection will use to transmit. This value defaults to 1500 when using IPv4, or a variable number 1280 or higher for IPv6, and does not generally need to be specified or changed.
