A FireWire® Ethernet adapter is a type of computer networking bus. It is capable of sending FireWire®-formatted signals through an Ethernet or Category 5 (CAT5) cable to another FireWire® adapter. Another name for a FireWire® Ethernet adapter is a FireWire® CAT5 repeater.

Typically, FireWire® connection cables are only 15 feet (4.6 m) long. To utilize the more cost-effective CAT5 Ethernet cables to establish longer network connections in large buildings, a FireWire® Ethernet adapter can send formatted data with Ethernet cables. A FireWire® Ethernet adapter is not capable of translating the data from FireWire® formatting to Ethernet formatting, however. The other end of the Ethernet cable cannot be directly plugged into the receiving computer's Ethernet port.

FireWire® is a high-speed data connection serial bus that is used to connect devices to a computer. It also can be used to connect several computers together in a local area network (LAN) so that users can quickly exchange data. Before Ethernet LAN connections were invented, FireWire® was used to set up a LAN that linked computers for online gaming and data transfer.

There are three types of FireWire® connectors. Desktop computers use a six-pin rectangular connector. Laptops or notebooks use a four-pin square connector. Computer devices that utilize the faster FireWire® 800 have a nine-pin plug on one end and a six-pin plug on the other for backward compatibility.

As an alternative to using a FireWire® Ethernet adapter, a circuit board or card with an attached Ethernet port and FireWire® port can be installed in a computer tower. This type of circuit board allows the simultaneous attachment of a device that uses FireWire® and a device that uses Ethernet cables. For example, a digital video camera FireWire® can be plugged into a computer that is connected to an Ethernet LAN. The saved video in the camera can then be sent to another user on the LAN.