How can I setup DNS and DHCP services on OpenLinux[tm] Server Release 3.1.1

by Federico G. Cigognini

Version 1.1

Contents

Objectives

The aim of this Back Office Solution Cookbook is to guide System Administrators through the process of configuring two of the most important services in IP Local Area Networks: Domain Name System (DNS) and Dynamic Host Configuration Protocol (DHCP).

This Cookbook should allow the reader to understand the concepts behind these two network services, and be able to setup a Caldera OpenLinux Server 3.1.1 system to serve on a Local Area Network. Moreover, by describing the procedures to configure clients, a simple small-scale network can be setup in a short period of time.

Introduction

DNS

IP (or Internet Protocol) networks, like any other network, work on the principle that each node (whether it is a workstation, network printer, or a router) has a unique identifier. Specifically to IP, this identifier is a 4-byte quantity (in the case of IPv4) known as the "IP Address," usually represented in a human readable form as a series of four, 1 to 3 digit numbers, separated by periods (or full-stops), as in:

   192.168.100.1

The IP address is used to access a specific node on the network and its functionality, for instance to print a document if it is a network printer.
On a small network it is quite easy to remember each node's IP address, however as the size of the network increases, so does the complexity of remembering bare numbers. For this reason almost all operating systems that support IP networking also allow users to maintain a local database which associates names, much easier to remember than numbers, with IP addresses. This local database usually consists of a file called "hosts," and allows accessing nodes on the network via their name rather than IP address, eg.

   # ftp fred

This solution has a limitation. Take for example a network with ten nodes, eight of which are either workstations or servers. These will each need to have a copy of the "hosts" database with their own, and the other nine nodes' name <-> address associations. If an eleventh node is added to the network, it will need to have its own copy of the "hosts" database, and once an IP address is assigned to it, the other machines' "hosts" databases will need to be modified to reflect this change. Maintenance of the "hosts" databases increases, and manageability decreases, exponentially with the addition of nodes on the network.

The Domain Name System (DNS) solves this limitation by providing a central name <-> address association database. Each node on the network can be instructed to query a central DNS server for the IP address associated to a name (a process known as Resolution), rather than looking it up in its internal "hosts" database. A change on the one DNS server will reflect on all the nodes on the network, increasing manageability.

DHCP

The number of IP addresses available is limited (especially IPv4 addresses), and unless the addresses used are private1 each one has an associated cost. For this reason, if a network doesn't have a constant number of nodes, it may be desirable to have multiple hosts "share" a single IP address. Obviously a single IP address cannot be shared by two nodes at the same time, but if one node is taken off the network, and its IP address is vacant, it may be desirable to have another node that has just been placed on the network use that address.

The Dynamic Host Configuration Protocol (DHCP) provides a means of "leasing" a range (or pool) of IP addresses. The most common application of DHCP is on networks where a number of laptops are added and removed throughout the day. In this case, the laptop user is not concerned what the machine's IP address is, so long as services on the network can be accessed for as long as required.

This document provides simple steps to configure Caldera OpenLinux Server 3.1.1 systems to provide both DNS and DHCP services, also describing how client systems can be configured to take advantage of these services. The client systems currently covered are:

Other systems may have different configuration processes, for those systems consulting the relative documentation is advisable.

Requirements

Hardware

The use of Caldera OpenLinux Server 3.1.1 to provide the services documented in this Back Office Cookbook does not require additional hardware, other than that used for any network server.
In order to test the configurations detailed below, at least one client system is needed. The client system should be networked, the sanity of the network infrastructure and client's connectivity to the server should be tested before attempting to follow these instructions.

NOTE: Although neither DNS and DHCP are dependent on the protocol at the Data Link Layer (Layer 2) of the ISO/OSI Reference Model (eg. Ethernet, Token Ring, FDDI), the configurations detailed in this document have only been tested on an Ethernet network. 2

Software

The main assumption made in this Back Office Solutions Cookbook is that the system in use is a "standard" Caldera OpenLinux Server 3.1.1 which has been installed with either "All Packages" or the "Network Server" profiles. A "standard" Caldera OpenLinux Server 3.1.1 system is one on which all packages installed are those distributed on the Caldera OpenLinux Server 3.1.1 media. No previous attempt should have been made to configure either of the services described in this Back Office Solutions Cookbook. Any system that does not fall into this classification may fail to produce expected results.

Names of packages used to test the configurations outlined in this Back Office Solutions Cookbook and their respective versions are listed in the table below. These packages should be installed on the system to be configured.
Package availability and the respective versions can be checked with the following command:

   # rpm -q <package name>

Required Packages
Package Name Version
bind 8.2.3-5
bind-doc 8.2.3-5
bind-utils 8.2.3-5
dhcp 3.0b2pl9-10
dhcp-server 3.0b2pl9-10
webmin 0.89-4

In order to access the Webmin[tm] configuration framework log onto KDE and select

   K -> Webmin

Alternatively start up a Netscape or Konqueror browser and point it to the URL:

   https://<system name>:1000/

where <system name> is the name of the Caldera Open Linux 3.1.1 system.

Preparation

Understanding of the requirements depends on the reader's knowledge of the basic concepts of IP networking. The documentation listed in the Background Reading section, should be consulted before proceeding.

All the necessary information should be gathered and the following criteria met.
-No other DHCP server should be on the same network as the test machine. A DHCP client generally sends a broadcast request requesting for an IP address to be leased to it. The presence of multiple DHCP servers on a single network may yield unpredictable results.
-DHCP clients and servers should be on the same physical network segment. Although this is not mandatory for either DNS or DHCP configuring DHCP services over bridged networks may be a complicated exercise, extending beyond the scope of this exercise.
A checklist of the most common details that need to be known in advance is also provided to assist in the preparation process, however more information may be required depending on the specifics of the site.

DNS Checklist
       Domain Name     eg. fredsdom.com 
       Network Address       .      .      .         eg. 192.168.100.0 
       Client 1 IP Address       .      .      .         eg. 192.168.100.10 
       Client 1 Hostname     eg. joe 
       Client 2 IP Address       .      .      .         eg. 192.168.100.11 
       Client 2 Hostname     eg. anne 
...
       Client n IP Address       .      .      .         eg. 192.168.100.n 
       Client n Hostname     eg. clientn 
DHCP Checklist
       DNS Server IP Address       .      .      .         eg. 192.168.100.1 
       DNS Server Subnet Mask       .      .      .         eg. 255.255.255.0 
       DNS Server Broadcast Address       .      .      .         eg. 192.168.100.255 
       First Address for Clients to Use       .      .      .         eg. 192.168.100.64 
       Last Address for Clients to Use       .      .      .         eg. 192.168.100.123 
       Default Gateway       .      .      .         eg. 192.168.100.254 
       Default Lease Duration     eg. 14000 seconds 
       Maximum Lease Duration     eg. 36000 seconds 

NOTE: One further assumption made in this Back Office Cookbook is that all the nodes are on a private network, protected against external access by a firewall.

Background Reading

A brief description is provided for each service, however a previous understanding of the basics is advisable.

Online Resources

http://pclt.cis.yale.edu/pclt/COMM/TCPIP.HTM Introduction to TCP/IP (Yale University)
ftp://fddisunsite.oit.unc.edu/pub/docs/unix-tutorials/courses/dns.ps The Domain Name Service (1992, University of West Ontario)
UnixWare 7 - Configuring Domain Name System (DNS) servers (Caldera International Inc.)

Books

O'Reilly - TCP/IP Networking 2nd ed.

DNS - Domain Name System

This section describes the steps required to configure a Caldera OpenLinux Server 3.1.1 system as a name server (a server that provides DNS services). Networks managed by name servers are subdivided into logical groups called "zones." A zone can be used to associate a domain name (eg. fredsdom.com) to one or more network subnets (eg. 192.168.100/24, 192.168.200/24, 192.168.300/24) and vice versa, and a Name server can be configured to manage the zone according to network layout and requirements.
There are different types of name servers, depending on how they manage a zone:
A name server is not limited to one type (i.e. managing one zone). In fact the majority of name servers active on the Internet manage multiple zones. This document will focus on each type individually (where possible), providing respective configuration examples.

Server-side Setup

DNS is a client-server communications mechanism. This section focuses on how to setup a Caldera OpenLinux Server 3.1.1 to serve DNS services.
For the purpose of clarity, the following sample configuration will be used throughout the examples:

Servers

  Domain (1): fredsdom.com
  Network Address (1): 192.168.100.0

  Primary Name Server's Name: ns1.fredsdom.com
  Primary Name Server's IP Address: 192.168.100.1
  Secondary Name Server's Name: ns2.fredsdom.com
  Secondary Name Server's IP Address: 192.168.100.2

  Domain (2): uk.fredsdom.com
  Network Address (2): 192.168.200.0
  Domain Primary Name Server IP Address: 192.168.200.1

Clients

  IP Address Node 1: 192.168.100.10
  Hostname Node 1: joe.fredsdom.com

  IP Address Node 2: 192.168.100.11
  Hostname Node 2: anne.fredsdom.com

  IP Address Node 3: 192.168.100.20
  Hostname Node 3: printer1.fredsdom.com

  IP Address Node 4: 192.168.200.15
  Hostname Node 4: joe.uk.fredsdom.com

NOTE: For the Webmin sections, DNS server configuration can be accessed by clicking on the Servers tab, and selecting the "BIND DNS Server" option. When configuring a "BIND DNS Server" for the first time Webmin requests whether the name server should be:
  • Setup for internal non-internet use only - recommended if the name server is located in
  • Setup as an internet name server, and root server information downloaded;
  • Setup as an internet name server, but using Webmin's older root server information;
Each section begins with a line that states which of these three options has been selected. When requested, select the option indicated, then click on the "Create Primary Configuration File and Start Nameserver" pushbutton once. If the page does not refresh automatically, click on the browser's "Reload" button to access the main configuration page. The numbered steps begin from this page.

Configuring a Primary/Master Name Server
A primary name server stores a local copy of the DNS records for a specific zone and answers queries for that zone

Step-by-Step Configuration (Webmin)

  1. Webmin will by default create two zones: "Root" and "127.0.0" These are listed in the Existing DNS Zones section
    2.  

  2. Create the primary zone by clicking on "Create a new master zone"
    3.  

  3. Populate the primary zone
    4.  

  4. Generally it may be desirable for certain nodes to have aliased names. For example the name server itself, ns1.fredsdom.com could also act as the mail server. Assigning an aliased name mailer1.fredsdom.com to ns1.fredsdom.com would allow future changes in the network infrastructure (eg. a new dedicated machine) to be reflected in just a name server change. To add an alias:
    5.  

  5. An e-mail sent to nsadmin@ns.fredsdom.com will result in the mail agent performing a name server lookup for the machine ns.fredsdom.com. Once the name is resolved into an IP address, the agent will attempt to connect directly to that node and submit the e-mail to its nsadmin user. However, the case of e-mail being sent to the user nsadmin@fredsdom.com is different, as fredsdom.com is a domain name. The mail agent will need to know where to send all e-mail for that domain, and to do so a specific lookup for the domain's mail server record is carried out. To add a mail server (or "mail exchange") record:
    6.  

  6. Now there should be sufficient information to run the server as the primary name server for the fredsdom.com domain

Configuring a Secondary/Slave Name Server
A secondary name server obtains a copy of the DNS records for a specific zone form that zone's primary name server. This is most useful for resilience, in case the primary name server suffers downtime

Step-by-Step Configuration (Webmin)

  1. Webmin will by default create two zones: "Root" and "127.0.0" These are listed in the Existing DNS Zones section
    2.  

  2. Create the secondary zone by clicking on "Create a new slave zone"

Configuring a Forwarding-only/Caching-only Name Server
A forwarding/caching-only name server is very useful in reducing traffic across different branches of a network. Each time a query is sent to a forwarding name server it will first attempt to reply using its cache and if the information is not available (or the cache is "cold") it queries another server higher up the hierarchy.
Another application for a forwarding name server may be in networks that don't have direct access to the Internet, but resolution of external names is still desirable

Step-by-Step Configuration (Webmin)

  1. Webmin will by default create two zones: "Root" and "127.0.0" These are listed in the Existing DNS Zones section
    2.  

  2. Create the forwarding zone by clicking on "Create a new forward zone"

Configuring a Stub Name Server
Certain networks can be quite large, spanning across several sites. A company that has for example offices in the United States of America the United Kingdom, and Australia may want to create different DNS zones, "us.fredsdom.com" - "uk.fredsdom.com" - "au.fredsdom.com" and delegate the name resolution for each zone to a different name server. One or more central servers visible to the company would then reroute queries to the zones' respective name servers. This section describes how a stub zone can be created to provide this functionality

Step-by-Step Configuration (Webmin)

  1. Webmin will by default create two zones: "Root" and "127.0.0" These are listed in the Existing DNS Zones section
    2.  

  2. Create the zone by clicking on "Create a new stub zone"

Client-side Setup

This section describes the steps necessary to configure Windows and Linux clients to take advantage of a DNS server on the network. The main assumption made at this stage is that TCP/IP networking has already been configured and works correctly, but no name server has been configured. To verify this it is sufficient to ping a machine on the network by its IP address, from a shell or the command line interpreter (COMMAND.COM or CMD.EXE).

NOTE: Before proceeding with the configuration and testing, please ensure that any Firewalling/Filtering software on the client is turned off. The Operating System or product specific documentation can be consulted later for information on how to fine-tune the Firewalling/Filtering software to allow DNS resolution to work

Microsoft Windows clients

Windows 9x, ME
Windows 9x, ME Network Configuration
  1. Click on Start -> Settings -> Control Panel
  2. Double-click on Network
Windows 9x, ME Network Configuration
  1. Select "TCP/IP -> <network adapter>" (where <network adapter> is the description of the LAN card) and click on Properties
  2. Click on the DNS Configuration tab. All fields in the form should be grayed out
Windows 9x, ME - DNS Configuration
  1. Click on "Enable DNS" It should now be possible to modify the fields
  2. Fill in the "Host" and "Domain" fields respectively with the client's own hostname, and the DNS domainname
  3. If a DNS server is available, enter its IP address in "DNS Server Search Order" and click on Add to add it to the list. If the client has access to multiple name servers these can all be added as detailed. The first listed will be queried first
  4. It may be useful to enter the DNS domainname in the "Domain Suffix Search Order" field. This will make it possible to access nodes on the network by using only the hostname, rather than having to specify the fully qualified domain name (hostname.domain).
    The order is also relevant. For example, a client in the "uk.fredsdom.com" zone would want to have "uk.fredsdom.com" listed first and "fredsdom.com" second. This way, when trying to contact the node "joe," the resolver would attempt to contact "joe.uk.fredsdom.com" first.
    Enter the first domain name, click on Add, repeat for all required domains, then OK all
  5. Restart Windows when prompted to

Windows NT 4
The following steps require administrator privileges. The reader should log onto the Windows NT 4 server with the "Administrator" account (or equivalent)

Windows 9x, ME Network Configuration
  1. Click on Start -> Settings -> Control Panel
  2. Double-click on Network
Windows 9x, ME Network Configuration
  1. Click on the Protocols tab
  2. Select "TCP/IP Protocol" and click Properties
Windows NT - DNS Configuration
  1. Click on the DNS tab
  2. Fill in the "Host" and "Domain" fields respectively with the client's own hostname, and the DNS domainname
  3. Click on Add in the "DNS Service Search Order" enter the name server's IP address and confirm. If the client has access to multiple name servers these can all be added as detailed. The first listed will be queried first, order can be changed by using the Up and Down buttons
  4. It may be useful to enter the DNS domainname in the "Domain Suffix Search Order" field. This will make it possible to access nodes on the network by using only the hostname, rather than having to specify the fully qualified domain name (hostname.domain).
    The order is also relevant. For example, a client in the "uk.fredsdom.com" zone would want to have "uk.fredsdom.com" listed first and "fredsdom.com" second. This way, when trying to contact the node "joe," the resolver would attempt to contact "joe.uk.fredsdom.com" first.
    Enter the first domain name, click on Add, repeat for all required domains
  5. Click OK to submit. Once in the Protocols properties click on the Bindings tab to ensure that the bindings are recreated
  6. Click on OK to confirm
  7. Reboot the system

Windows 2000, XP
The procedures to setup Windows 2000 and Windows XP systems to use DNS are very similar. A few differences may be noticed in the dialogs, but overall one description should fit all.

The steps require administrator privileges. The reader should log onto the Windows 2000/XP server with the "Administrator" account (or equivalent).

Windows XP Local Area Connection
  1. Right-Click on My Network Places and select Properties
  2. Right-Click on Local Area Connection and select Properties
Windows 2000, XP Local Area Connection Properties
  1. Select "Internet Protocol (TCP/IP)" and click on Properties
  2. Click on the General tab. All fields referring to DNS in the form should be grayed out
Windows 2000, XP - Internet Properties
  1. Click on "Use the following DNS server addresses:" It should now be possible to modify the fields
  2. Fill in the "Preferred DNS server" and "Alternate DNS server" fields with the primary and secondary name servers' IP addresses, then click on Advanced...
Windows 2000, XP - DNS Configuration
  1. Click on the DNS tab. This should list the name servers entered in the previous form
  2. It may be useful to enter the DNS domainname in the "Append these DNS suffixes" list. This will make it possible to access nodes on the network by using only the hostname, rather than having to specify the fully qualified domain name (hostname.domain).
    The order is also relevant. For example, a client in the "uk.fredsdom.com" zone would want to have "uk.fredsdom.com" listed first and "fredsdom.com" second. This way, when trying to contact the node "joe," the resolver would attempt to contact "joe.uk.fredsdom.com" first.
    Click on "Append these DNS suffixes (in order)"
  3. Click on Add, enter the first domain name and confirm, repeat for all required domains
  4. OK all, there should be no need to restart Windows

Linux clients
The current section describes how to configure a Caldera OpenLinux 3.1.1 system (whether Workstation or Server) to act as a DNS client, and take advantage of the domain name service configured through this Cookbook.

Step-by-Step Configuration (Webmin)
  1. To access DNS client via the Webmin framework click on the Hardware tab, in the main form
  2. Select "Network Configuration"
  3. Select "DNS Client"
  4. Click on "Save" to commit the changes

Testing the Configuration
The steps in this section are simple ways to check that the configuration has been successful. A DNS server can be tested by configuring it as a client to itself and following the instructions for Linux Clients.

Microsoft Windows Clients
Windows ping test
  1. Click on Start -> Run
  2. On Windows 9x clients type command, on Windows NT, 2000, XP type cmd to access the command line (DOS)
  3. Try to ping other nodes on the network, first using their IP address, then using the hostnames

Linux Clients
OpenLinux 3.1.1 ping test
  1. Click on the Terminal icon in the "Panel" to start up a Terminal window
  2. Try to ping other nodes on the network, first using their IP address, then using the hostnames
OpenLinux 3.1.1 ping test
  1. Use nslookup to test the resolution
    1. On the command line type nslookup
    2. If the client can communicate with the name server, the DNS server's IP address and name will be shown and a prompt displayed
    3. Try formulating a few queries by setting the record types to
      • A for Name -> Address
      • PTR for Address -> Name
      • NS for the name server records
      • CNAME for the alias records
      • MX for mail records
        • eg.
        > set type=A
        > ns1

DHCP - Dynamic Host Configuration Protocol

This section focuses on how to configure a Caldera OpenLinux Server 3.1.1 system as a DHCP server (a server that provides dynamic host configuration services)

Server-side Setup

Like DNS, DHCP is a client-server communications mechanism. This section focuses on how to setup a Caldera OpenLinux Server 3.1.1 to manage a pool of IP addresses that can be assigned to clients. DHCP can also be used to provide the clients with information relative to other services on the local area network (for example the IP address of a name server or the default gateway). This section covers the additional services that are used most often.

The following sample configuration will be used throughout the examples:

Server

  Domain (1): fredsdom.com
  Network Address (1): 192.168.100.0

  Primary Name Server's Name: ns1.fredsdom.com
  Primary Name Server's IP Address: 192.168.100.1
  Secondary Name Server's Name: ns2.fredsdom.com
  Secondary Name Server's IP Address: 192.168.100.2

Clients

  Domain (2): uk.fredsdom.com
  Network Address (2): 192.168.200.0
  Domain Primary Name Server IP Address: 192.168.200.1

  IP Address Node 1: 192.168.100.10
  Hostname Node 1: joe.fredsdom.com

  IP Address Node 2: 192.168.100.11
  Hostname Node 2: anne.fredsdom.com

  IP Address Node 3: 192.168.100.20
  Hostname Node 3: printer1.fredsdom.com
  Hardware Address Node 3:00:30:C1:57:70:71

  Default Gateway: 192.168.100.254

The OpenLinux DHCP server has the ability to manage both single and "shared" network configurations (whereby multiple subnets share the same physical network).

NOTE: For the Webmin sections, DHCP server configuration can be accessed by clicking on the Servers tab, and selecting the "DHCP Server" option.

Single Network Configuration

Step-by-Step Configuration (Webmin)
  1. Initially no subnets, shared networks or hosts should be configured.
  2. Configure the subnet by clicking on "Add a new subnet"
  3. Define the client configuration options by clicking on the newly created subnet, and on "Edit Client Options" in the Edit Subnet form
  4. Create a pool of addresses that can be leased out by clicking on "Add an address pool" in the "Address Pools for Subnet" section
  5. In some cases it may be necessary, or preferable, to assign fixed IP addresses to specific DHCP clients, for example on a network where Dynamic DNS is not available. Under these circumstances it is acceptable for clients to have different IP addresses (and therefore different DNS entries), but network printers should always have the same address and hostname.
    To create this "semi-static" mapping, click on "Add a new host" in the Edit Subnet form
  6. Once the configuration is saved by clicking on "Save" in this form the DHCP service can be started via the "Start Server" button in the main configuration form

Client-side Setup

This section details the steps necessary to configure Windows and Linux clients to take advantage of a DHCP server on the network. The main assumption made at this stage is that TCP/IP networking has been tested by configuring the clients with static IP addresses and verifying that connectivity is functioning. To verify this it is sufficient to ping a machine on the network by its IP address, from a shell or the command line interpreter (COMMAND.COM or CMD.EXE)

NOTE: Before proceeding with the configuration and testing, please ensure that any Firewalling/Filtering software on the client is turned off. The Operating System or product specific documentation can be consulted later for information on how to fine-tune the Firewalling/Filtering software to allow DHCP to work

Microsoft Windows clients

Windows 9x, ME
Windows 9x, ME Network Configuration
  1. Click on Start -> Settings -> Control Panel
  2. Double-click on Network
Windows 9x, ME Network Configuration
  1. Select "TCP/IP -> <network adapter>" (where <network adapter> is the description of the LAN card) and click on Properties
  2. Click on the IP Address tab
Windows 9x, ME - DHCP Configuration
  1. Click on "Obtain an IP address automatically"
  2. If a DNS server is available on the network, click on the DNS Configuration tab. All fields in the form should be grayed out
Windows 9x, ME - DNS Configuration
  1. Click on "Enable DNS" It should now be possible to modify the fields
  2. Fill in the "Host" and "Domain" fields respectively with the client's own hostname, and the DNS domainname
  3. The DHCP server has been configured to pass the remaining information to the client, so no other field should need editing
  4. OK all and restart Windows when prompted to

Windows NT 4
The following steps require administrator privileges. The reader should log onto the Windows NT 4 server with the "Administrator" account (or equivalent)

Windows 9x, ME Network Configuration
  1. Click on Start -> Settings -> Control Panel
  2. Double-click on Network
Windows 9x, ME Network Configuration
  1. Click on the Protocols tab
  2. Select "TCP/IP Protocol" and click Properties
Windows NT - DHCP Configuration
  1. Click on the IP Address tab
  2. Click on "Obtain an IP address from a DHCP server"
    3. Windows NT - Confirm DHCP Configuration
  3. When prompted, confirm the intention to use DHCP
Windows NT - DNS Configuration
  1. If a DNS server is available to this client, click on the DNS tab
  2. Fill in the "Host" and "Domain" fields respectively with the client's own hostname, and the DNS domainname
  3. The DHCP server has been configured to pass the remaining information to the client, so no other field should need editing
  4. Click on OK to confirm
  5. Reboot the system

Windows 2000, XP
The procedures to setup Windows 2000 and Windows XP systems to use DHCP are very similar. A few differences may be noticed in the dialogs, but overall one description should fit all.

The steps require administrator privileges. The reader should log onto the Windows 2000/XP server with the "Administrator" account (or equivalent).

Windows XP Local Area Connection
  1. Right-Click on My Network Places and select Properties
  2. Right-Click on Local Area Connection and select Properties
Windows 2000, XP Local Area Connection Properties
  1. Select "Internet Protocol (TCP/IP)" and click on Properties
  2. Click on the General tab
Windows 2000, XP - Internet Properties
  1. Select "Obtain an IP address automatically"
  2. Select "Obtain DNS server address automatically"
  3. Click on the Advanced... button
Windows 2000, XP - DHCP Configured
  1. The "IP address" box should display "DHCP Enabled"
  2. OK all, there should be no need to restart Windows

Linux clients
The current section describes how to configure a Caldera OpenLinux 3.1.1 system (whether Workstation or Server) to act as a DHCP client, and take advantage of dynamic configuration options provided by the server

Step-by-Step Configuration
The following steps require administrator privileges. The reader should log onto the K Desktop Environment with the "root" account (or equivalent)

OpenLinux 3.1.1 KDE Control Center
  1. Click on K -> Control Center
OpenLinux 3.1.1 Network Interface Configuration
  1. Select System -> Network -> Interfaces
  2. Click the name of the network interface (usually "eth0")
  3. Click on "Dynamic Addresses with DHCP"
  4. Ensure that the interface is enabled
  5. Click on Save and Apply to make the configuration active

Testing the Configuration
Brief steps will be listed throughout this section, to verify that the dynamic configuration provided through DHCP has been successful

Microsoft Windows Clients
Windows ipconfig test
  1. Click on Start -> Run
  2. On Windows 9x clients type command, on Windows NT, 2000, XP type cmd to access the command line (DOS)
  3. Type ipconfig /all to list the configuration of the network interface. IP Address, subnet mask and default gateway should correspond to those setup in the DHCP server configuration
Windows ipconfig test
  1. Some Windows 95 clients do not have the ipconfig command
  2. Click on Start -> Run
  3. Type winipcfg and check the configuration details

Linux Clients
OpenLinux 3.1.1 ifconfig test
  1. Click on the Terminal icon in the "Panel" to start up a Terminal window
  2. Type ifconfig -a to obtain details of the interface configuration. IP Address, netmask, broadcast address should match those setup in the DHCP server's configuration
  3. Type cat /etc/resolv.conf to check if the DNS configuration has been setup correctly (if provided)
  4. Type netstat -nr to check that the routers have been configured correctly

DNS and DHCP Combined

Dynamic DNS (DDNS)

The Caldera OpenLinux Server 3.1.1 DHCP daemon has been built without DDNS support. This feature is therefore not currently supported

References and Further Reading

DNS

Online Resources
http://www.dns.net/dnsrd/ DNS Resources Directory
http://www.linuxdoc.org/HOWTO/DNS-HOWTO.html DNS HOWTO
Books
O'Reilly - DNS and Bind 4th ed.

DHCP

Online Resources
http://www.caldera.com/support/docs/openlinux/3.1/OLsag/index.html Caldera OpenLinux System Administration Guide
http://www.isc.org/products/DHCP/dhcp-v3.html ISC Dynamic Host Configuration Protocol (DHCP)
Books
Prentice Hall - The DHCP Handbook, 1/e

General

Online Resources
http://www.ietf.org/rfc.html IETF Request for Comments Repository
http://www.caldera.com/LDP/HOWTO/Diskless-HOWTO.html Diskless Nodes HOW-TO document for Linux
Books

Notes

  1. Some IP addresses are reserved for private use, and are not routable over the Internet. These are all the addresses in the:
       10.xxx.yyy.zzz (Class A)    172.16.yyy.zzz (Class B)    192.168.yyy.zzz (Class C)
    For further information, see the Further Reading section.
  2. DHCP works at the Media Access Control (MAC) sub-layer. As Ethernet transmits data octets (including the MAC address) LSB first, and Token Ring/FDDI transmit MSB first, the DHCP server needs to be aware of and capable of managing this difference.

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Thank you.

Copyright © 2002, Caldera International. All Rights Reserved Worldwide. Caldera International assumes no responsibility for the accuracy or completeness of the information in this document. The use of this information or the implementation of any of these techniques is a customer responsibility and depends upon the customer's ability to evaluate and integrate them into the customer's operational environment. Information in this document is subject to change without notice, and does not imply a commitment on the part of Caldera.

Caldera, the Caldera logos and OpenLinux are trademarks or registered trademarks of Caldera International, Inc. in the U.S.A. and other countries. Linux is a registered trademark of Linus Torvalds. All other brand and product names are trademarks or registered marks of the respective owners.