Datasheet

“main” (Installation and Administration) — 2004/6/25 — 13:29 — page 515 — #541
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21
Linux in the Network
One way to use DHCP is to identify each client using the hardware address
of its network card (which is fixed in most cases) then supply that client
with identical settings each time it connects to the server. DHCP can also be
configured so the server assigns addresses to each interested host dynam-
ically from an address pool set up for that purpose. In the latter case, the
DHCP server tries to assign the same address to the client each time it re-
ceives a request from it (even over longer periods). This, of course, does not
work if there are more client hosts in the network than network addresses
available.
With these possibilities, DHCP can make life easier for system adminis-
trators in two ways. Any changes (even bigger ones) related to addresses
and the network configuration in general can be implemented centrally by
editing the server’s configuration file. This is much more convenient than
reconfiguring lots of client machines. Also it is much easier to integrate ma-
chines, particularly new machines, into the network, as they can be given
an IP address from the pool. Retrieving the appropriate network settings
from a DHCP server can be especially useful in the case of laptops regu-
larly used in different networks.
A DHCP server supplies not only the IP address and the netmask, but also
the host name, domain name, gateway, and name server addresses for the
client to use. In addition to that, DHCP allows for a number of other pa-
rameters to be configured in a centralized way, for example, a time server
from which clients may poll the current time or even a print server.
The following section gives an overview of DHCP without describing the
service in every detail. In particular, it shows how to use the DHCP server
dhcpd in your own network to manage its entire setup from one central
point.
21.11.2 DHCP Software Packages
Both a DHCP server and DHCP clients are available for SUSE LINUX. The
DHCP server available is dhcpd (published by the Internet Software Con-
sortium). On the client side, choose between two different DHCP client
programs: dhclient (also from ISC) and the DHCP client daemon in the
dhcpcd package.
SUSE LINUX installs dhcpcd by default. The program is very easy to
handle and is launched automatically on each system boot to watch for a
DHCP server. It does not need a configuration file to do its job and should
work out of the box in most standard setups. For more complex situations,
use the ISC dhclient, which is controlled by means of the configuration file
/etc/dhclient.conf.
515SUSE LINUX Enterprise Server