One DHCP server, two VLANs?

Karl Denninger karl at
Tue Jan 12 20:52:40 UTC 2016

This seems like it should be possible without a lot of hand-wringing,
but I can't find the magic smoke recipe for it....  :-)

Topology is a wireless AP with two SSIDs on it.  One is on Vlan 1 (just
to make it simple) the other on Vlan 2.  AP is cabled to a switch that
knows how to do VLANs of course.

Vlan 1 has access to all the "inside" stuff; servers and resources, etc.
Vlan 2 has access ONLY to the outside Internet via a gateway with a DNS
server on it, etc.

Both Vlan 1 and 2 have distinct IP address assignments on different subnets.

Access from Vlan 2 to the outside works fine; this allows you to have a
"guest" network where nobody can see anything inside, but they can get
out to the Internet at-large.  Provided I hard-assign the IP number for
things on VLAN 2 it works fine.

The DHCP server is on both VLANs via virtual interfaces (FreeBSD) with
the port on the switch being told to send both through; it sees and
handles traffic from both VLANs just fine.

But.... I cannot start two instances of dhcpd (one on each
sub-interface.)  Nor can I find a way to tell dhcpd to read requests
from both.

Am I stuck with running the server for the VLAN on a different machine? 
If so that's probably ok, but doing it all on one machine would be nice....

Karl Denninger
karl at <mailto:karl at>
/The Market Ticker/
/[S/MIME encrypted email preferred]/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 2996 bytes
Desc: S/MIME Cryptographic Signature
URL: <>

More information about the dhcp-users mailing list