[Dnsmasq-discuss] ignore mac address for one of the dhcp

[Geert Stappers]

On Mon, Apr 13, 2020 at 10:18:31AM -0400, John Siu wrote:
> On Mon, Apr 13, 2020 at 4:54 AM Geert Stappers wrote:
> > On Sun, Apr 12, 2020 at 03:14:33PM -0400, John Siu wrote:
> > > I am running dnsmasq on a multiple port box. Following are dhcp config
> > > for the lan and dmz ports:
> > >
> > > ---
> > >
> > > ## LAN
> > > dhcp-range=tag:lan,::1,constructor:lan,ra-names,72h # IPv6
> > > dhcp-range=tag:lan,172.16.168.130,172.16.168.250,72h # IPv4
> > > dhcp-option=tag:lan,option:router,172.16.168.1 # option 3 default gw
> > > dhcp-option=tag:lan,option:dns-server,172.16.168.1
> > >
> > > ## DMZ
> > > dhcp-range=tag:dmz,::1,constructor:dmz,ra-names,72h # IPv6
> > > dhcp-range=tag:dmz,10.10.10.100,10.10.10.120,72h # IPv4
> > > dhcp-option=tag:dmz,option:router,10.10.10.1 # option 3 default gw
> > > dhcp-option=tag:dmz,option:dns-server,10.10.10.1
> > >
> > > ---
> > >
> > > They work correctly for network connected to those ports.
> >
> > I wonder how.
> >
> > I mean: The provided information looks incomplete to me.
> > Might be due an attempt to make the config more generic.
> >
> >
> >
> Following is the complete 92-dhcp.conf file I am using. It is not generic.
> I have interface name "lan" and "dmz" setup in network config.

Ah

> ---
> log-dhcp
> quiet-dhcp
> quiet-dhcp6
> quiet-ra
> 
> enable-ra
> 
> ## LAN
> dhcp-range=tag:lan,::1,constructor:lan,ra-names,72h # IPv6
> dhcp-range=tag:lan,172.16.168.130,172.16.168.250,72h # IPv4
> dhcp-option=tag:lan,option:router,172.16.168.1 # option 3 default gw
> dhcp-option=tag:lan,option:dns-server,172.16.168.1 # option 6 dns
> #dhcp-option=tag:lan,option:ntp-server,172.16.168.1
> 
> ## DMZ
> dhcp-range=tag:dmz,::1,constructor:dmz,ra-names,72h # IPv6
> dhcp-range=tag:dmz,10.10.10.100,10.10.10.120,72h # IPv4
> dhcp-option=tag:dmz,option:router,10.10.10.1 # option 3 default gw
> dhcp-option=tag:dmz,option:dns-server,10.10.10.1 # option 6 dns
> #dhcp-option=tag:dmz,option:ntp-server,10.10.10.1
> 
> ## Lease
> dhcp-hostsfile=/etc/dnsmasq.d/extra/dhcp.hosts
> dhcp-leasefile=/etc/dnsmasq.d/extra/dhcp.lease
> ---
> 
> > > However, I am having issue with the switch which connect to both dmz
> > > and lan ports with different VLANs. As those VLAN ports share the same
> > > mac address, sometimes the switch will pick up IP from the lan side,
> > > and sometimes from the dmz side.
> > >
> > > How can I make dnsmasq only serve IP on the lan side for this specific mac
> > > address?
> >
> > Tell more about what you have.
> >
> The switch is a Netgear GS908E. It has 8 ports. I setup 2 vlan, one for
> dmz, one for lan. So there is one cable from my server dmz port to the dmz
> vlan, same for lan.

Thanks.  I'm not used to interface names like 'lan' or 'dmz'.
I'm used to interface names like 'eth0' and 'enp181s0f2'


> The switch is configure to use dhcp for its ip.

OK, Acknowledge.  (As in "I respect your design decission" )


> However, it requests dhcp from all ports. As a result, sometime it pick up
> 172.x.x.x, and sometimes it pickup 10.x.x.x address.

(and that is the challenge we are facing)


I have been reading the dnsmasq manual page  (again ;-) But I could not
find a clear solution for coping with duplicate MAC-addresses.

The is `--dhcp-ignore=tag:...` no use in this case.


Idea  (wild idea?)

  dhcp-host:01:00:18:4D:C0:3F:0E,172.16.168.251,12h



In other words: Make a "static reserveration" for the swith in LAN




Regards
Geert Stappers
-- 
Silence is hard to parse