On Tue, Apr 20, 2021 at 4:38 AM Kurt Jaeger <p...@freebsd.org> wrote: > > Hello, > > does anyone know how the system selects the MAC/ether adress of a > newly-created tap0 device ? > > ifconfig tap0 create > > has this: > > tap0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500 > options=80000<LINKSTATE> > ether 58:9c:fc:10:98:02 > groups: tap > media: Ethernet autoselect > status: no carrier > nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > > How is that selected ? > > We had a case where two devices selected the same ether/MAC... >
tap MACs are derived from the hostid (/etc/hostid) -- you generally end up with the same MAC in one of two scenarios: 1.) The hosts have identical /etc/hostid (bad, probably an issue with machine provisioning where the hostid file is getting copied and thus, not regenerated at boot?), or 2.) hostid isn't being preloaded #2 may be the case if it's a machine that doesn't use loader, or you've specifically disabled it with hostuuid_load="NO" in loader.conf. I've got a WIP to improve the failure mode for that one to fallback to a fully random MAC. #1 can be fixed by moving hostid out of the way and letting the hostid rc scripts generate and save a new one, assuming they're not getting their data from bogus/duplicate smbios uuids. Thanks, Kyle Evans _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
