IGMP version higher than net.inet.igmp.default_version

[etihwo]

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• I have read the contributing guide lines at https://github.com/opnsense/src/blob/master/CONTRIBUTING.md
• I am convinced that my issue is new after having checked both open and closed issues at https://github.com/opnsense/src/issues?q=is%3Aissue

Describe the bug

The tunable net.inet.igmp.default_version has not effect on the IGMP version used on interfaces. The problem was also present in 24.7.

Tip: to validate your setup was working with the previous version, use opnsense-revert (https://docs.opnsense.org/manual/opnsense_tools.html#opnsense-revert)

To Reproduce

Steps to reproduce the behavior:

1. Go to 'System: Settings: Tunables' and set 2 for net.inet.igmp.default_version
2. Apply settings and reboot to be sure that change is taken into account
3. Open a shell and run sysctl net.inet.igmp to see that default_version is 2
4. Run ifmcstat -f inet to notice that igmpv3 is indicated for each interface

Expected behavior

When runing the command ifmcstat -f inet, the igmp version should be less or equal than the net.inet.igmp.default_version

Describe alternatives you considered

I have applied the commit freebsd/freebsd-src@b94ec00 as this topic has been discussed in the main branch of FreeBSD. However, it is not sufficient and ifmcstat -f inet still indicate version 3.

In addition to the commit above, I have changed VNET_DEFINE_STATIC(int, igmp_default_version) = IGMP_VERSION_2; in igmp.c. This modification allows:

• to have IGMPv2 after a reboot
• to switch to IGMPv3 at runtime if net.inet.igmp.default_version is set to 3

However, this modification does not allow:

• to switch from IGMPv3 to IGMPv2 at runtime

Environment

OPNsense 25.1 (amd64)