Re: [PATCH 0/2] Add option to omit DHCP Client Identifier

On Thu, 21 Dec 2023 at 22:18, Marcel Holtmann <[email protected]> wrote:
>
> Hi Grant,
>
> >> While recently working a customer project, I ran into an issue after
> >> upgrading the OS to a newer version which uses connman for network
> >> management.
> >>
> >> The DHCP client in the old OS didn't include option 61 (Client
> >> Identifier) but connman does. In this scenario, when the system
> >> reboots after an upgrade, it changes IP address, which can get very
> >> confusing, especially if a UI is waiting for the device to come back
> >> alive to signal completion of the update.
> >>
> >> This proposed change adds an option to main.conf - OmitClientIdentifier,
> >> which, if set to true causes that option to not be added to DHCP
> >> packets.
> >>
> >> The default behaviour is retained in case no option is set in main.conf.
> >>
> >> The change is relatively small, and I'm posting it here in case it is
> >> helpful for connman users facing the same issue.
> >>
> >> Please feel free to consider or exclude it. If there's anything that I
> >> can do to improve it to match upstream requirements, please let me know
> >> and I'll do what I can to help.
> >
> > António,
> >
> > It’s slightly different than the client identifier; however, did you experiment with the existing AllowHostnameUpdates configuration option?
> >
> > Also, connman should request the last-issued DHCP address to the DHCP server. Assuming another client hasn’t reserved it first, the client should get a semi-stable IP address. Did you chase that down as well?
> >
> > Finally, if the DHCP server is configured to serve a different IPv4 address for the specified client ID rather than the one the client has, might this be better addressed at the DHCP server? Though, I can see that you might not have access to the server.
>
> I think that Denis already mentioned this. We need to kill the ConnMan DHCP client in favor of the one from ELL.

Sorry, a combination of holiday season and spam filter made me miss
this message.
If this is a pointless change given the short term plans for connman,
that's fine, sure.

FWIW, it'd be nice to consider some option to not fill the Client
Identifier in DHCP packets in the future. It seems legitimate to
upgrade a system that didn't use that option to a new version running
connman, and the likelyhood of it changing IP in the process is high.

Cheers,
António


>
> Regards
>
> Marcel
>