What's new

How to use N66U as a DHCP relay?

  • SNBForums Code of Conduct

    SNBForums is a community for everyone, no matter what their level of experience.

    Please be tolerant and patient of others, especially newcomers. We are all here to share and learn!

    The rules are simple: Be patient, be nice, be helpful or be gone!


Occasional Visitor
I was trying to take a look at the config files on github, but I didn't see any way to use DHCP/Bind as a relay for a isc-dhcp-server/bind9 setup.

Though, I realized that there might be a bit of trouble with my guest network.

My configuraton setup has a main SSID, and a Guest SSID. However, I have a server that I planned on using for Bind9 and isc-dhcp-server, and is already setup. I would like if all clients could be directed to the the server, rather than using the dhcp server and dns server on the N66U itself. I know you can do this in dd-wrt.

Any help or guidance would be appreciated.
This may do what you want....

On the LAN-DHCP Servers tab, set

Enable DHCP Server to No

Advertise router's IP in addition to user-specified DNS to No
and put the address of your local server as DNS Server 1 (or leave it blank)
I was confused when you said "use DHCP/Bind". Presumably you want to use the routers dnsmasq as a relay to your isc-dhcp-server/bind9 server?

If so have a look at the following dnsmasq parameter:
--dhcp-relay=<local address>,<server address>[,<interface]

Configure dnsmasq to do DHCP relay. The local address is an address allocated to an interface on the host running dnsmasq. All DHCP requests arriving on that interface will be relayed to a remote DHCP server at the server address. It is possible to relay from a single local address to multiple remote servers by using multiple dhcp-relay configs with the same local address and different server addresses. A server address must be an IP literal address, not a domain name. In the case of DHCPv6, the server address may be the ALL_SERVERS multicast address, ff05::1:3. In this case the interface must be given, not be wildcard, and is used to direct the multicast to the correct interface to reach the DHCP server.

Access control for DHCP clients has the same rules as for the DHCP server, see --interface, --except-interface, etc. The optional interface name in the dhcp-relay config has a different function: it controls on which interface DHCP replies from the server will be accepted. This is intended for configurations which have three interfaces: one being relayed from, a second connecting the DHCP server, and a third untrusted network, typically the wider internet. It avoids the possibility of spoof replies arriving via this third interface.

It is allowed to have dnsmasq act as a DHCP server on one set of interfaces and relay from a disjoint set of interfaces. Note that whilst it is quite possible to write configurations which appear to act as a server and a relay on the same interface, this is not supported: the relay function will take precedence.

Both DHCPv4 and DHCPv6 relay is supported. It's not possible to relay DHCPv4 to a DHCPv6 server or vice-versa.
Any luck with setting up a DHCP relay? This appears to be something I want to do as well so that my ISP modem provides my DHCP but my AC68U acts as my firewall. I'm not familiar with configuring dnsmasq on the router and don't want to brick it if I mess this up.

Support SNBForums w/ Amazon

If you'd like to support SNBForums, just use this link and buy anything on Amazon. Thanks!

Sign Up For SNBForums Daily Digest

Get an update of what's new every day delivered to your mailbox. Sign up here!