FW: FBSD router/firewall with dhclient & dhcpd

Edward Carmody ecarmody at shoregroup.com
Sun Feb 1 12:24:44 PST 2004

Hi, I'm trying to replace my Linksys
router/firewall/nat box with a FreeBSD box...I'm
in the configuring/testing phase before I put it
into production...

My *potential* problem is that my ISP
(Cablevision) re-addresses their DNS servers
often.  My question is: is there a way to
dynamically update the "option
domain-name-servers" values in dhcpd.conf from the
"nameserver" values my ISP-facing, dhclient-using
interface is writing into "resolv.conf"?

Or, more simply, how can my DHCP server hand out
*known-fresh-and-good* ISP dns server addresses
gathered from the wan-facing dhcp client??  The
linksys box I have now does this auto-magically...

Info the FreeBSD box:

-FreeBSD Oberon 5.1-RELEASE FreeBSD 5.1-RELEASE
#0: Thu Jun  5 02:55:42 GMT 2003
root at wv1u.btc.adaptec.com:/usr/obj/usr/src/sys/GEN
ERIC  i386

-I have dhclient running correctly on my
to-be-ISP-facing interface (tested using a Cisco
2620 as dhcp server);

-I have dhcpd running correctly on my LAN-facing
interface (currently serving all home LAN

-I have verified that routed is exchanging RIP
updates with an internal Cisco 2620 (I run
multiple VLANs internally); will have to get VLANs
running on FreeBSD later...

-I think natd is set up correctly, haven't tested

-I have ipfw running full-open for internal
testing on home LAN.

All help is appreciated...thanks!

Ed C.

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