---
# System prepended metadata

title: 20220506_network-changes-fedora-37

---

# 20220506_network-changes-fedora-37

- default MACAddressPolicy in Fedora
    - https://github.com/coreos/fedora-coreos-tracker/issues/919
    - proposal: change to MACAddressPolicy=none
    - RHEL9: https://bugzilla.redhat.com/show_bug.cgi?id=1921094
    
NOTES:
    - RHEL8 and RHEL9 have the old behavior
    - If we want Fedora to change we should also propose this upstream to systemd
        - the idea is that if it doesn't make sense for Fedora does it make sense
          for upstream systemd?
    - Action - Thomas to start mailing list discussion upstream in systemd
               (systemd-devel@lists.freedesktop.org) to discuss the merits of
               this change. Dusty to point fedora-devel list towards the discussion.
    
    
- defaulting to EUI-64 for IPv6 SLAAC on server-like editions
    - https://github.com/coreos/fedora-coreos-tracker/issues/907
    
NOTES:
    - LR: we think this is still important for default



---
Communicating the VM addressing information to the hypervisor
- What does libvirt do?

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```
Lubomir from the NetworkManager crowd here. From where I stand, reverting
the defaults back to obsolete EUI-64 method is a complete no-go. It has been
deprecated for very good reasons, IETF's position is detailed in [RFC 8064].

Apart from the privacy issues, the problems of EUI-64 mechanism affecting
the servers are:

* The EUI-64 identifiers, being based on hardware address change with
  replacement on interface cards. Not great on servers.
* The mechanism produces a single address. On DAD failures, the machine
  ends up with not connectivity.

If the machine needs a predictable address, either the provisioning should
assign a static address or utilize DHCPv6. For the cases where this wouldn't
be possible (and the environment is controlled enough for the various issues
with EUI-64 don't apply, e.g. virtual networks), we are willing to provide
a way to switch defaults to EUI-64 in system configuration, but we're
strongly opposed to making this any sort of default.

I'll be joining the meeting in an hour, happy to discuss this further.

Pointers to relevant RFCs, for reference:

[RFC 7217] A Method for Generating Semantically Opaque Interface
           Identifiers with IPv6 Stateless Address Autoconfiguration (SLAAC)
           <https://www.rfc-editor.org/rfc/rfc7217>

[RFC 8064] Recommendation on Stable IPv6 Interface Identifiers
           <https://www.rfc-editor.org/rfc/rfc8064>
```


