DHCP Help Again

[tegner at nada.kth.se]

Quoting "Robert G. Brown" <rgb at phy.duke.edu>:
Is there a convenient way to obtain static ip-addresses using dhcp without
having to explicitly write down the mac-addresses in dhcpd.conf?

Regards,

/jon



> On Wed, 3 Apr 2002, Adrian Garcia Garcia wrote:
> 
> For one thing don't use the range statement -- it tells dhcpd the range
> of IP numbers to assign UNKNOWN ethernet numbers.  You are statically
> assigning an IP number in your "free" range to a particular host with a
> KNOWN ethernet number below.  I don't know what dhcpd would do in that
> case -- something sensible one would hope but then, maybe not.  The
> range statement is really there so you can dynamically allocate
> addresses from the range to hosts you may never have seen before that
> you don't care to ever address by name (as they might well get a
> different IP number on the next boot).  
> 
> DHCP servers run by ISP's not infrequently use the range feature to
> conserve IP numbers -- they only need enough to cover the greatest
> number of connections they are likely to have at any one time, not one
> IP number per host that might ever connect.  Departments might use it to
> give IP numbers to laptops brought in by visitors (with the extra
> benefit that they can assign a subnet block that isn't "trusted" by the
> usual department servers and/or is firewalled from the outside by an
> ip-forwarding/masquerading host).
> 
> You want "only" static IP's in your cluster, as you'd like nodo1 to be
> the same machine and IP address every time.
> 
> Be a bit careful about your use of domain names.  As it happens, I don't
> find cluster.org registered yet (amazingly enough!) but it is pretty
> easy to pick one that does exist in nameservice in the outside world.
> In that case you'll run a serious risk of routing or name resolution
> problems depending on things like the search order you use in
> /etc/nsswitch.conf.  Even my previous example of rgb.private.net is a
> bit risky.
> 
> You should run a nameserver (cache only is fine) on your 192.168.1.1
> server, presuming it lives on an external network and you care to
> resolve global names.
> 
> Similarly you may want:
> 
>  option routers		192.168.1.1;
> 
> if you want internal hosts to be able to get out through your (presumed
> gateway) server.
> 
> Finally, if you want nodo1 to come up knowing its own name without
> hardwiring it in on the node itself, add
> 
>  option host-name	nodo1;
> 
> to its definition.
> 
> I admit that I do tend to lay out my dhcpd.conf a bit differently than
> you have it below but I don't think that the differences are
> particularly significant, and you have a copy of the one I use anyway if
> you want to play with the pieces.  You should find a log trace of
> dhcpd's activities in /var/log/messages, which should help with any
> further debugging.
> 
> On your nodo1 host, make sure that:
> 
> cat /etc/sysconfig/network-scripts/ifcfg-eth0
> DEVICE=eth0
> BOOTPROTO=dhcp
> ONBOOT=yes
> 
> and
> 
> cat /etc/sysconfig/network
> NETWORKING=yes
> HOSTNAME=nodo1
> 
> and that in /etc/modules.conf there is something like:
> 
> cat /etc/modules.conf
> alias parport_lowlevel parport_pc
> alias eth0 tulip
> 
> (or instead of tulip, whatever your network module is).
> 
> If you then boot your e.g. RH client it SHOULD just come up,
> automatically try to start the network on device eth0 using dhcp as its
> protocol for obtaining and IP number, ask the dhcp server for an address
> and a route, and just "work" when they come back.
> 
>   Hope this helps.
> 
>        rgb
> 
> > server-name "server.cluster.org"
> >  
> > subnet 192.168.1.0 netmask 255.255.255.0
> > {
> >   range 192.168.1.2         192.168.1.10   #my client has the ip
> > 192.168.1.2
> >                                                                 #and
> my
> > server the static ip 192.168.1.1
> >  option subnet-mask                             255.255.255.0;
> >  option broadcast-address                    192.168.1.255;
> >  option domain-name-server                 192.168.1.1;  
> >  option domain-name                            "cluster.org";
> >  
> >  host  nodo1.cluster.org
> >  {
> >     hardware ethernet 00:60:97:a1:ef:e0; #here is the address of the
> > client's card
> >     fixed-address        192.168.1.2;
> >  }
> > } 
> >  
> > And finally some files on my server.
> >  
> > NETWORK
> > ------------------------------------------
> > networking = yes
> > hostname =server.cluster.org
> > gatewaydev = eth0
> > gatewaye=
> > ------------------------------------------
> >  
> > HOSTS ( In my server and in the client I have the same on this file )
> > ------------------------------------------
> > 127.0.0.1             localhost
> > 192.168.1.1         server.cluster.org
> > 192.168.1.2         nodo1.cluster.org
> >  
> >  
> > Ok thats the information, I am a little confuse, could you help me
> please
> > =). I can´t detect the mistake, I dont know if is the server or some
> card
> > =s. Thanks for all.
> > 
> >
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> 
> -- 
> Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
> Duke University Dept. of Physics, Box 90305
> Durham, N.C. 27708-0305
> Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu
> 
> 
> 
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