Re: How To: Linksys DHCP assigns address based on MAC?

In article <h2ngj412aam@xxxxxxxxxxxxxxxxx>,
J.J. O'Shea <try.not.to@xxxxxxxxxxx> wrote:

On Sat, 4 Jul 2009 02:00:30 -0400, Barry Margolin wrote
(in article <barmar-DA6257.02003004072009@xxxxxxxxxxxxxxxxxxxxxxxxxx>):

In article <h2movb036c@xxxxxxxxxxxxxxxxx>,
J.J. O'Shea <try.not.to@xxxxxxxxxxx> wrote:

On Fri, 3 Jul 2009 23:09:07 -0400, Gene E. Bloch wrote
(in article <wizyxh36qmpl.1mggm4zi65arb$.dlg@xxxxxxxxxx>):

On Fri, 03 Jul 2009 13:27:46 -0700, YA MacUser wrote:

Greetings and thanks for reading this.
With D-Link consumer routers, it is easy to have the DHCP server always
assign the same LAN address to a given MAC number so port forwarding
will go to the computer with that LAN address.
I need to do this to a Linksys WRT54G router but can't find a
recognizable page in the setup. Where to control the DHCP server?
Kind regards

Can't you tell the computer with that MAC address to use a fixed IP
address?

That's the way it works in Windows (and it's easy to do).



If he uses a fixed IP that's within the DHCP pool, the router might
allocate
that IP to something else. That would be bad. Most routers allow for IPs
to
be reserved for particular MAC addresses. The Linksys User Guide details
how.
Chapter 8, IIRC.

So he should use a fixed IP that's NOT within the DHCP pool.

Yes. IIRC Linksys routers usually set the DHCP pool to be from 192.168.1.10
on up to 192.168.1.254. The router itself is usually 192.168.1.1, and of
course 192.168.1.0 and 192.168.1.255 can't be used, so that leaves
192.168.1.2 to 192.168.1.9 available for use.

It's been a while since I initially set mine up, so I could be
remembering incorrectly, but I think the default range starts at .100,
not .10. But even if not, it's simple to change the range it uses, if
you need more fixed addresses.

The problem with configuring a static IP, though, is that you also have
to configure DNS statically. It would be preferable to get the ISP's
DNS from the router via DHCP. Apple has an option in the Network
preference for "Using DHCP with manual address", but this doesn't seem
to work with Linksys routers. We had a thread a couple of years ago
about this.



I have a WRT54G, and AFAIK it doesn't have a way to configure static
MAC->IP mappings for the DHCP server. Maybe this can be added with
DD-WRT firmware.

I could be wrong about this, but I'd be surprised if I were as that would
make Linksys the only vendor which doesn't support reserved IPs, which is a
standard TCP feature. Certainly the routers I have at home and at the office
support reserved IPs. I use them all the time for printers, servers, NAS
boxes, and laptops.

I'm practically certain I'm correct. This isn't a "standard TCP
feature", it's a configuration option in some (perhaps most) DHCP
servers. It doesn't affect the wire protocol, so it's not something
that needs to be standardized across implementations.

--
Barry Margolin, barmar@xxxxxxxxxxxx
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***
.

Relevant Pages

  • Re: Blocking access to a network
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    ... >> setting the DHCP range for the entire /24 block is a bad idea. ... The only DHCP server I know that will hand out its own IP address is ... Some routers just don't have enough memory to store a large range. ... Jeff Liebermann jeffl@xxxxxxxxxxxxxxxxxxxxxx ...
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  • Re: DHCP ON XP
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  • Re: How To: Linksys DHCP assigns address based on MAC?
    ... Where to control the DHCP server? ... Most routers allow for IPs ... The Linksys User Guide details ...
    (comp.sys.mac.comm)
  • Re: How To: Linksys DHCP assigns address based on MAC?
    ... With D-Link consumer routers, it is easy to have the DHCP server always ... Where to control the DHCP server? ... Can't you tell the computer with that MAC address to use a fixed IP ... The Linksys User Guide details ...
    (comp.sys.mac.comm)
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