Network Setup Question

Lane lane at joeandlane.com
Sat Nov 11 04:23:27 UTC 2006


On Friday 10 November 2006 21:56, Doug Hardie wrote:
> On Nov 10, 2006, at 19:34, Jonathan Horne wrote:
> > On Friday 10 November 2006 19:17, Doug Hardie wrote:
> >> I have a bit of an unusual network setup situation.  I have a machine
> >> that is only used to store backups.  It gets moved around to
> >> different locations occasionally so it has to be able to live on a
> >> 192.168.1.x or a 10.0.1.x network without reconfiguration.  I also
> >> need a fixed last address byte so I can connect to it remotely.  I
> >> initially set it up with DHCP and then used an alias for the .250
> >> address on both networks.  That worked, but caused problems for the
> >> local network in one location.  The particular user couldn't
> >> understand why sometimes his computer got different IP addresses.  So
> >> I tried to establish the 192.168.1.250 as the primary address and
> >> added an alias of 10.0.1.250.  That works  in both environments
> >> except that there is no default route.  Is there a way to negotiate
> >> just a default route via DHCP and not an IP address? or is there a
> >> way to set the default route based on which IP address is in use?
> >> Thanks.
> >> _______________________________________________
> >
> > dhclient.conf can get pretty granular as to exactly what you want
> > from your
> > DHCP server.  myself, i use it to get everything, but to ignore the
> > domain
> > search mine tries to provide.
> >
> > man dhclient.conf and you will see tons of options (and some really
> > good
> > examples too).
>
> There are lots of options all right, but I couldn't find anything
> that would cause it not to negotiate the IP address.  All of the
> other options are configurable.
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Doug,

I'm no expert, but it seems to me that your requirements are a little too 
optimistic.

If I understand correctly, you want this machine to be able to connect to 
multiple heterogenous networks, and always get the same last byte for its ip.

The only way to do that reliably, in my mind, is to have each dhcp server on 
each network assign a static address based upon the MAC address of your 
computer.

If you do not have access to the DHCP server configuration on a particular 
network then you must manually configure the nic.

Assuming that you know the universe of networks that you will connect to ... 
say 3 or 300 possible networks ... then you could write a script 
in /usr/local/etc/rc.d to test various network configs ... but you might be 
better off just manually configuring the nic and moving on, as you cannot 
guarantee that the terminal byte of the ip will be available on any given 
network.  IP just doesn't work that way.

I'd be interested in any solution you may scare up, as I am faced with a 
similar situation.  My solution is to just use static assignment, with an 
identifiable NETBIOS name in Samba.

Good Luck

lane


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