[Dnsmasq-discuss] Restrict DHCP providing default gateway to *one* host on one network

[Will Dennis (Live.com)]

Interesting question...

Here's the lines from my syslog containing the string "tag" for machines
that are requesting DHCP off the particular network in question;

Apr 24 06:28:27 hypervisor-host dnsmasq-dhcp[13550]: 1449630067 tags:
vl20-ovsbr0
Apr 24 07:12:05 hypervisor-host dnsmasq-dhcp[13550]: 1336540602 tags:
wanem-20, vl20-ovsbr0
Apr 24 07:40:22 hypervisor-host dnsmasq-dhcp[13550]: 915834710 tags:
vl20-ovsbr0
Apr 24 07:59:40 hypervisor-host dnsmasq-dhcp[13550]: 1449630067 tags:
vl20-ovsbr0
Apr 24 08:51:43 hypervisor-host dnsmasq-dhcp[13550]: 935263674 tags:
wanem-20, vl20-ovsbr0
Apr 24 08:51:55 hypervisor-host dnsmasq-dhcp[13550]: 733937082 tags:
wanem-20, vl20-ovsbr0
Apr 24 08:53:01 hypervisor-host dnsmasq-dhcp[13550]: 3863084474 tags:
wanem-20, vl20-ovsbr0
Apr 24 09:03:35 hypervisor-host dnsmasq-dhcp[13550]: 915834710 tags:
vl20-ovsbr0
Apr 24 09:31:01 hypervisor-host dnsmasq-dhcp[13550]: 3242786234 tags:
wanem-20, vl20-ovsbr0
Apr 24 09:32:32 hypervisor-host dnsmasq-dhcp[13550]: 2773024186 tags:
wanem-20, vl20-ovsbr0
Apr 24 09:38:36 hypervisor-host dnsmasq-dhcp[13550]: 1449630067 tags:
vl20-ovsbr0
Apr 24 10:28:56 hypervisor-host dnsmasq-dhcp[13550]: 915834710 tags:
vl20-ovsbr0
Apr 24 10:33:42 hypervisor-host dnsmasq-dhcp[16101]: 240582074 tags:
wanem-20, vl20-ovsbr0
Apr 24 10:33:42 hypervisor-host dnsmasq-dhcp[16101]: 257359290 tags:
wanem-20, vl20-ovsbr0
Apr 24 10:33:42 hypervisor-host dnsmasq-dhcp[16101]: 274136506 tags:
wanem-20, vl20-ovsbr0
Apr 24 10:35:27 hypervisor-host dnsmasq-dhcp[16101]: 2158278434 tags:
vl20-ovsbr0
Apr 24 10:35:27 hypervisor-host dnsmasq-dhcp[16101]: 2158278434 tags:
vl20-ovsbr0
Apr 24 10:42:07 hypervisor-host dnsmasq-dhcp[16101]: 391708090 tags:
wanem-20, vl20-ovsbr0

As you can see, all machines have the tag "vl20-ovsbr0" (since I believe
that tag is added as a result of the request coming in from that interface)
but only the WANem host has tag "wanem-20" as well (as a result of the
stanza "dhcp-mac=set:wanem-20,52:54:00:45:8c:6a" in my dnsmasq.conf file) --
my guess is that I'd have to match on ALL tags on the request, but maybe
only one would do... ??


-----Original Message-----
From: Brad Morgan [mailto:b-morgan at concentric.net] 
Sent: Wednesday, April 24, 2013 2:49 PM
To: 'Will Dennis (Live.com)'; 'Simon Kelley'
Cc: dnsmasq-discuss at lists.thekelleys.org.uk
Subject: RE: [Dnsmasq-discuss] Restrict DHCP providing default gateway to
*one* host on one network

> So again, my requirement is to send a router value (default gateway) 
> in
response 
> to ALL DCHP client > DHCPDISCOVER requests coming in off interface
> vl20-ovsbr0 EXCEPT the one tagged "wanem-20" which should get NO (i.e. 
> null) router option sent to it.

> Empirically, the line I have 
> (dhcp-option=tag:vl20-ovsbr0,tag:wanem-20,3)
is 
> working for me and does exactly the above. 

Correct me if I am wrong, but wouldn't "dhcp-option=tag:wanem-20,3" do the
same thing?

I too, am trying to learn from this example!

Brad