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Title: Client configuration of DHCP (6.0 6.1)

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Client configuration of DHCP (6.0 6.1)
Applies to
SuSE Linux: Version 6.0, 6.1
Symptom:
You are trying to configure your Linux computer as a DHCP client on your
local network but it is not working as you expected.
Reason:
There can be many reasons why the DHCP client is not working. It is most
important that the DHCP server is directly accessable. For simple local
network configurations, this means that the client and server should be on
the same physical network (ie no routers inbetween the client and server) as well
as on the same logical network (ie both on the same class C subnet). More
advanced networks will have DHCP relay agents, so the above described
restrictions will not apply (ie @home cable access in the US). It is
also possible that the DHCP server is sending incomplete information
when it sends the DHCP_OFFER to the client. Please note that the
DHCP server and the DHCP client shouel NOT be on the same machine!!
Solution:
- The DHCP server is working...right? The best way to verify this with
another client. NOTE: The DHCP server and the DHCP client should not be
on the same machine!! If you are using your SuSE Linux as the DHCP server, make
sure that you have installed the package "dhcp" which is located in the
Series "n" ( Network-Support (TCP/IP, UUCP, Mail, News)). The main
configuration file is /etc/dhcpd.conf and it must be modified
accordingly (ie available IP address range, DNS servers, gateways etc...).
The config file contains well documented examples, and there are also man
pages for dhcpd and dhcpd.conf. You need to start the service with the
script:
/sbin/init.d/dhcp start
This service can also be automatically started on bootup, by modifying the
/etc/rc.config file and setting the variables as necessary:
START_DHCPD="yes"
DHCPD_INTERFACE="eth0"
It is recommended that these variables are set from YaST -> System
Administration -> Change Configuration file, as this will automatically
run SuSEConfig.
- Make sure that you have installed the DHCP client package "dhclient"
which is located in the Series "n" ( Network-Support (TCP/IP, UUCP, Mail,
News)). Once the package is installed, you need to configure the
interface to be a DHCP interface. This can easily be done from YaST ->
System Administration -> Network Configuration -> DHCP client.
- Use the utility
traceroute
to see if the DHCP server
is on the same subnet and reachable, or if there is a host in between.
If you are testing from the DHCP client, you will obviously need to
temporarily configure it with a static address. If the DHCP server is on
the other side of a router, you will either have to change your network
topology or install and configure a DHCP relay agent.
- The DHCP client does not recieve enough information. You may need
to modify the DHCP client configuration file /etc/dhclient.conf
so that the clients request to the server will indicate that it requires
additional information, for example subnetmask and DNS. In the configuration
/etc/dhclient.conf file, remove the comment from the
front of the line:
require subnet-mask, domain-name-servers;
The other preferable option is to change the configuration of the DHCP
server so that it automatically offers this information.
- Does the
DHCP_REQUEST
packet even make it to the server?
You can verify this by having a look in the /var/log/messages
file on the server. In this file you can see the entire DHCP transaction taking palce.
- If you have two network interfaces and one of them needs to be a dhcp
interface, proceed as follows:
Configure both interfaces in YaST for the appropritate driver.
For example, use YaST -> System Administration -> Integrate hardware into
system -> Configure networking device, to select the correct driver for
each network interface. The DHCP interface must be eth0, this is
hard coded into the dhclient script. Then set the DHCP client to start on bootup from
YaST -> System administration -> Network configuration -> DHCP Client.
After you reboot your system you should notice that the eth0 interface is
up. You can verify this with the command ifconfig. You need to manually
bring up the eth1 interface. For example:
ifconfig eth1 192.168.1.4 broadcast 192.168.1.255 netmask 255.255.255.0 up
In this example the eth1 interface has an IP address of 192.168.1.4 and is
on a class C subnet.

Keywords: DHCP, CLIENT, BOOTP

Categories:
DHCP

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SDB-dhcp_client, Copyright SuSE GmbH, Nuremberg, Germany
- Version: 11. Jun 1999
SuSE GmbH - Last generated: 31. Jan 2000 03:56:09
by jmigliac
with sdb_gen 1.00.0