[nSLUG] DHCP and name resolution question

Donald Teed donald.teed at gmail.com
Fri May 6 00:08:04 ADT 2005

Maybe I'm missing something, but I don't know why moby can't
just use a fixed IP.  The DHCP server in the wireless router
is an option, not a requirement, of connecting to it.  In general,
anytime you need to be able to get to a dynamically assigned
IP address machine, there has to be some way of knowing
where it is.  The DHCP config could be set up to always
assign a specific IP based on the MAC address of the
wireless client hardware (many routers can do this and
a Linux DHCP server certainly can), but that might be
more effort than you really need to get things done.  I'd
just go with a static IP and enter that in the hosts
file or DNS or whatever you use for name lookups.
Ditto for any additional clients.

On 5/5/05, Mike Spencer <mspencer at tallships.ca> wrote:
> So I got a DHCP client working by changing one line in an rc.d file.
> Nothing to it. But there's a problem on my LAN that I don't quite get.
> (Isn't there always? :-)
>     My main box and another (bogus & alien) are connected to a router
>     by cable and have fixed IP addresses assigned.
>     If the laptop (moby) runs a DHCP client over wireless, the
>     (wireless) *router* itself has a DHCP server and assigns an
>     address to moby.
>     So far, so good. I can reach bogus and alien *from* moby, say,
>     with ping or telnet or "mount bogus:/".
>     BUT bogus and alien have no way of knowing what IP address moby
>     has.
> Is there some general way to deal with this? [1] Is NIS/yp* the thing
> that will do this?  I'm happy to RTFM but there are so *many* long and
> complicated FMs that I haven't read yet....  So I would be grateful
> for a pointer in the right direction.
> (This question is all about a LAN; internet connection is by
> dialup. The router isn't involved in the connection to the "real"
> internet.)
> TIA,
> - Mike
> [1] I guess I have a workaround: telling the router (through its admin
>     interface) that there is only one address it's allowed to issue to
>     clients.  Then the other 2 hosts can be configured as if that were
>     moby's fixed address.  But that isn't a general solution: it (a)
>     wouldn't allow a second wireless DCHP client to join the LAN and
>     (b) would cause a new and different DHCP client to be recognized
>     wrongly as moby.
> --
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                            /V\
> mspencer at tallships.ca                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^
> --
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