There are several DHCP servers available for U*X-like OSes,
both commercial and free. One of the more popular free DHCP servers
is Paul Vixie/ISC DHCPd. Currently the latest version is 2.0 (suggested
for most users) but 3.0 is in beta testing. You can get them from
ftp://ftp.isc.org/isc/dhcp/
Some of the distributions provide binary packages for dhcpd so
skip the following section if you got it installed that way.
After you download unpack it. After you do cd into the
distribution directory and type: ./configure
It will take some time to configure the settings. After it is done type:
make and make install.
When done with installation type ifconfig -a. You
should see something like this:
eth0 Link encap:10Mbps Ethernet HWaddr 00:C0:4F:D3:C4:62
inet addr:183.217.19.43 Bcast:183.217.19.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2875542 errors:0 dropped:0 overruns:0
TX packets:218647 errors:0 dropped:0 overruns:0
Interrupt:11 Base address:0x210 |
If it doesn't say MULTICAST you should reconfigure your
kernel and add multicast support. On most systems you will not
need to do this.
Next step is to add route for 255.255.255.255. Quoted from DHCPd README:
"In order for dhcpd to work correctly with picky DHCP clients
(e.g., Windows 95), it must be able to send packets with an
IP destination address of 255.255.255.255. Unfortunately,
Linux insists on changing 255.255.255.255 into the local
subnet broadcast address (here, that's 192.5.5.223). This
results in a DHCP protocol violation, and while many DHCP
clients don't notice the problem, some (e.g., all Microsoft
DHCP clients) do. Clients that have this problem will appear
not to see DHCPOFFER messages from the server."
Type: route add -host 255.255.255.255 dev eth0
If you get a message "255.255.255.255: Unknown host",
you should try adding the following entry to your
/etc/hosts file:
Then, try:
route add -host all-ones dev eth0 |
or
route add 255.255.255.0 dev eth0 |
eth0 is of course the name of the network device you
are using. If it differs change appropriately.
Now you need to configure DHCPd. In order to do this you
will have to create or edit /etc/dhcpd.conf. There
is a graphical interface for dhcpd configuration under KDE ( http://www.kde.org/ ) called kcmdhcpd
that is very similar to the DHCP configurator on Windows NT. When KDE
2.0 comes out it should come with kcmdhcpd or you could get it directly
from:
ftp://ftp.us.kde.org/pub/kde/unstable/apps/network/
If you want to configure it by hand follow instructions below.
Most commonly what you want to do is assign IP addresses randomly. This
can be done with settings as follows:
# Sample /etc/dhcpd.conf
# (add your comments here)
default-lease-time 600;
max-lease-time 7200;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255;
option routers 192.168.1.254;
option domain-name-servers 192.168.1.1, 192.168.1.2;
option domain-name "mydomain.org";
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.10 192.168.1.100;
range 192.168.1.150 192.168.1.200;
} |
This will result in DHCP server giving a client an IP address
from the range 192.168.1.10-192.168.1.100 or
192.168.1.150-192.168.1.200. It will lease an IP address for
600 seconds if the client doesn't ask for specific time
frame. Otherwise the maximum (allowed) lease will be 7200 seconds. The
server will also "advise" the client that it should use 255.255.255.0 as
its subnet mask, 192.168.1.255 as its broadcast address, 192.168.1.254 as
the router/gateway and 192.168.1.1 and 192.168.1.2 as its DNS servers.
If you need to specify a WINS server for your Windows clients you
will need to include the netbios-name-servers option e.g.
option netbios-name-servers 192.168.1.1; |
You can also assign specific IP addresses based on clients
ethernet address e.g.
host haagen {
hardware ethernet 08:00:2b:4c:59:23;
fixed-address 192.168.1.222;
} |
This will assign IP address 192.168.1.222 to a client with ethernet
address 08:00:2b:4c:59:23.
You can also mix and match e.g. you can have certain clients getting
"static" IP addresses (e.g. servers) and others being alloted
dynamic IPs (e.g. mobile users with laptops). There are a number of other
options e.g. nis server addresses, time server addresses etc., if you
need any of those options please read the
dhcpd.conf man page.
There is only one thing to do before starting the server. In most cases
DHCP installation doesn't create a dhcpd.leases
files. This file is used by DHCPd to store information about current
leases. It is in the plain text form so you can view it during the
operation of DHCPd. To create dhcpd.leases type:
touch /var/state/dhcp/dhcpd.leases |
This will create an empty file (file size = 0).
Some of the older version of dhcpd 2.0 placed the file in
/etc/dhcpd.leases. You do not need to make any
changes to the leases file it will be manipulated by the dhcpd. If you
get a message saying that file exists simply ignore it and go to the
next step.
You can now invoke the DHCP server. Simply type (or include in the bootup
scripts)
This will invoke dhcpd on eth0 device. If you want to invoke it
on another device simply supply it on the command line e.g.
To verify that everything is working fine you
should first turn on the debugging mode and put the server
in foreground. You can do this by typing
Then boot up one of your clients and check out the console of your server.
You will see a number of debugging messages come up. If everything works out
fine you are done :-). Quit dhcpd and start it without the
-d -f and arguments. If you want
dhcpd to start at boot-up include dhcpd in e.g.