Xbox Debug Monitor

The Xbox Debug Monitor (XBDM) is a feature of Xbox Development Kits that provides remote debugging, file management, console discovery, and other services on TCP/UDP port 731. It is loaded by debug kernels at startup from C:\xbdm.dll and its configuration is read from C:\xbdm.ini. XBDM is distinct from KD and uses a different wire protocol.

Name Answering Protocol

An Xbox Development Kit (XDK) can be assigned a debug name that identifies it on the local network. XBDM provides the ability to resolve a debug name to an IP address (forward lookup), resolve an IP address to a debug name (reverse lookup), and discover all XDKs on the local network using a very simple UDP-based protocol.

Name Answering Protocol Packet

Offsets	Octet	0								1
Octet	Bit	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
0	0	Type								Name Length
2	16+	Name

A NAP packet contains 3 fields, the last of which is variable-length. The minimum length of a NAP packet is 2 bytes and the maximum is 257. Invalid packets are silently dropped by XBDM.

Type

This unsigned 8-bit field may contain the values 1 (lookup), 2 (reply), or 3 (wildcard).

Name Length

This unsigned 8-bit field specifies the length of the Name field and should be a value from 0 to 255. For Type 3 packets, this field should always be 0. For Type 2 and Type 3 packets, this field should never be 0.

Name

This variable-length field contains the ASCII-encoded debug name for Type 1 and Type 2 packets. The number of bytes in this field is given by the Length field. It should not contain any NUL characters.

Forward Lookup

To resolve a debug name to an IP address, send a Type 1 NAP packet containing the debug name to be resolved to UDP address 255.255.255.255:731. The XDK with that name will respond with a Type 2 NAP packet and its IP address can be retrieved from the UDP header. There is no way to prevent multiple XDKs being assigned the same debug name, so it's possible that the client may receive replies from multiple IP addresses.

Reverse Lookup

To resolve an IP address to a debug name, send a Type 3 NAP packet with no name (length 0) to the IP address on UDP port 731. Assuming the target is actually an XDK, it will respond with a Type 2 NAP packet containing its name. This is very similar to the Console Discovery process (below), except that by sending the wildcard packet to a single IP address, only that XDK will respond.

Console Discovery

To discover all XDKs on the local network, sends a Type 3 NAP packet with no name (length 0) to the UDP address 255.255.255.255:731. Each XDK will respond with a Type 2 NAP packet containing its name. As with a forward lookup, the client may receive multiple replies with the same name, but different IP addresses.

Remote Debugging and Control Protocol

TODO

External Links

• Yelo Neighborhood – An open-source re-implementation of Xbox Neighborhood written in C#.
• ViridiX – An open-source collection of Xbox debugging libraries and tools written in C#.