All MacOS 27 systems have the same uuid.getnode() value

[sebastianw]

Bug report

Bug description:

All MacOS 27 systems have the same hardware address because all MAC-Addresses are displayed as 02:00:00:00:00:00.

Running on MacOS 27:

uuid.getnode()
2199023255552
uuid.getnode().to_bytes(6)
b'\x02\x00\x00\x00\x00\x00'

I did not find a workaround and according to an Apple developer this is a feature.

CPython versions tested on:

3.14

Operating systems tested on:

macOS

[sebastianw]

The system-provided python does something different than the homebrew installed python:

▶ /opt/homebrew/bin/python3.14 -c "import uuid; print(uuid.getnode())"
2199023255552

▶ /usr/bin/python3 -c "import uuid; print(uuid.getnode())"
116394603438933

Also I noticed that real MAC-Addresses are sill displayed when running as root with sudo ifconfig.

[ronaldoussoren]

The developer forum post linked to by the OP mentions a new entitlement: com.apple.developer.networking.topology-observation. Adding this should fix this issue (although I haven't checked yet if more work is needed).

[gvanrossum]

What breaks as a result of this? The OP doesn't say.

[sebastianw]

@gvanrossum I'm using it in a tool that generates unique IPv6 ULA networks, according to RFC4193.

The algorithm uses an EUI64 identifier which is derived from a MAC-Address and part of the algorithm input, so I use the uuid.getnode function for that. It also uses NTP-Time, so theoretically the created network would only be the same on two MacOS 27 machines that call it at exactly the same time, which is very unlikely.

I only noticed it while working on the code and the very unusual MAC-Address/Node-ID came up in debug output.