The Xbox contains an Ethernet module and one RJ45 connector. Additionally, separate modem and wireless accessories were considered when developing the console. Eventually, an official wireless adapter was released based on a "D-Link 108AG Gaming Adapter" in the end of 2003.
Integrated network adapter
Integrated in the Nvidia Southbridge MCPX chip which is similar to the nForce chips.
The Xbox MAC address is stored in the EEPROM. The network driver, including the protocol stack is contained in the XDK. The kernel only contains a small number of exports to reset and get the state of the NIC.
The Xbox Linux team used the binary drivers from Nvidia[FIXME].
Ethernet II, Src: Microsof_f2:00:00 (00:50:f2:f2:00:00), Dst: Broadcast (ff:ff:ff:ff:ff:ff) MS Network Load Balancing Signature: Unknown (0x584f4258) Version: 1.1 Unique Host ID: 3118682055 Cluster IP: 184.108.40.206 (220.127.116.11) Host IP: 18.104.22.168 (22.214.171.124) Signature Data - Unknown (1481589336)
based on the "D-Link 108AG Gaming Adapter", the Xbox MN-740 Wireless Bridge bundled with an Xbox setup disc (which would update the dashboard if necessary). It was also described on Microsoft's website.
- AR5312 CPU (MIPS 4Kc core?)
- AR5212 RoC (Radio on Chip) for 2.4 Ghz 802.11b/g.
- KS8721B physical layer transciever
- some EEPROM which hold the MAC address (based of FCC pictures and Firmware analysis)
- IC42S16400 8Mb ram
- SST39LF0?0A (1 or 2 Mb) (the FCC picture is unclear on the size part due to writing) 
The onboard 3 LEDs are Power, Wireless and Xbox (called Ethernet on the PCB). The board seems to have Jtag and what appears to be Serial test pins exposed.
This wireless bridge runs a closed source version of the "ThreadX JADE/Green Hills Version G126.96.36.199" RTOS. The firmware contains a copyright string of: "Copyright (c) Microsoft Corporation All Rights Reserved Device is Xbox Compatible"
The latest firmware is separated by a boot and runtime firmware  :
- MN740_01.03.00.0005_BOOT.bin, "Xbox Wireless Adapter (MN-740) boot firmware"
- MN740_01.00.02.0022_RUNTIME.bin, "Xbox Wireless Adapter (MN-740) runtime firmware"
There were at least 2 firmware updates for download:
Judging by the firmware filenames above, there should also be an MN-740 1.00 and MN740 1.03.
The shipped firmware does not support WPA or WPA2. A "firmware" hack based on the D-Link firmware adds WPA support, rendering Dashboard support unfunctional and changing settings require connecting to the LAN port using a PC (or web browser capable application).
Software (Xbox setup disc)
The setup disc is a CD. It contains an XISO filesystem that contains only a "default.xbe" which contains a dashboard updater.
- Patent: Managing access to content
- Patent: Network architecture for secure communications between two console-based gaming systems
- Patent: Architecture for manufacturing authenticatable gaming systems
- Patent: Discovery and distribution of game session information
- Patent: Security gateway for online console-based gaming
- Patent: Presence and notification system for maintaining and communicating information
- Patent: Multiple user authentication for online console-based gaming
- Xbox Wireless adapter manual
- Flashing the Firmware of an Xbox MN-740 Wireless Adapter to a D-Link 108AG to support WPA Security
- FCC entry of Xbox MN-740 Wireless Adapter (with IC writing intact)