On Wed, Dec 15, 2021 at 04:26:42PM +0100, Tuxo wrote:

Hi list

My router and my docsys modem power on at the same time. the modem is
handing out dhcp offers of 192.168.100/24 . I assume they are meant for internal set up purposes and dhclient on my router should not catch or respond to them. Only the final offer after modem bootup has completed does contain the WAN subnet and a lease time of 4 hours.

Can I configure dhclient on my router to discard lease offers from a certain subnet? I could also try to match the lease time, the 192.168.100/24 lease time is only several seconds (!!) short, the real one will be 4 hours or
more and come with a valid WAN subnet mask.

I never had this problem before, so I don't know how to change dhclient's behaviour to a bogus lease offer.

Maybe iptables could assist and block multicast traffic from/to the wrong subnet? I'm not sure I would still get the actual WAN lease then.

Which dhcp client?

if dhclient, the config allows specifying a reject subnet range, so you
could do something like:
reject 192.168.100.0/24

--
Len Sorensen

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Mi, 15 dec 21, 16:26:42, Tuxo wrote:

Hi list

My router and my docsys modem power on at the same time. the modem is
handing out dhcp offers of 192.168.100/24 . I assume they are meant for internal set up purposes and dhclient on my router should not catch or respond to them. Only the final offer after modem bootup has completed does contain the WAN subnet and a lease time of 4 hours.

Hello,

This appears to be a general networking question, that happens to
involve one or more ARM systems.

If one of your systems is running Debian (the router?) the question is
better suited on the debian-user list

https://lists.debian.org/debian-user

I would suggest you add more information on the router (hardware and
software configuration, which port is connected to the modem, etc.).

This list is meant for issues with porting packages to the arm*
architectures in Debian or issues with getting Debian to run at all on specific ARM hardware.

Kind regards,
Andrei
--
http://wiki.debian.org/FAQsFromDebianUser

-----BEGIN PGP SIGNATURE-----

iQIzBAEBCAAdFiEE5E64jOIbhY42OXqk/8eFRO8iNBwFAmG9pCAACgkQ/8eFRO8i NBzP8g/7BNB578V9apzII9kAWwVUe7p1ODnQxnxv9UmiQ/j1ni9NZzFAAJaenXfr SuU0UPpMEdTFO4SvOoMxgo3ywIUkKFPEd09CWTmglMQroYKlFOGLCZjoA6wp0y9C JIT+E8UKSG6G0gUaSnR34OVNyZsTm+q6HmeHo6icMwqkD++eXGNGG/6OyGnRSr7b S9aogGwpQLqn4gRK4y6JsEbk0mwF9eCHjHv7dF+qfxpYr3aAp/+SZdPnQMUShZS6 Pu38Cn/EScgbMl2A07bbpl65Sa8DtDmNYWGcrPEHzpsfDLoy8du/Jj0bpVYMAQ8F 9uNzGNMQsgW7+k+BJSZJif75k6sGyrTJz2Rju910oNnMPGcZf8B1Ned40A8bSHQv 4530NXGcfX1VMyrCGnZy6VcvgirVqSX88Xtp+fMOo3Gb6gTPzAVfBpIPZToLoGIS eYSarTz09o02re4QlofC5yVlzgezEyfkxUP6X/kXebOYqxTqHl+8FgL4uutSDDN6 PgfD9wMgLiBRg337tDiqqYjfkP5Y+BK5zbzaOAJJyReHIM92epMDcFruhOzHuao7 IS+miAVDlatlVZxQ5P5VqPE03pojua3uLrHBmXNYg4UUZrDjIaL0tZ8Fbj4r4fgx y7lLcVBLkYlhE1qfQjBS09iPhTyIX1GcWRPJik6FGRP6Vd8brR4=
=Iisf
-----END PGP SIGNATURE-----

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)