DHCP mini-HOWTO

Vladimir Vuksan

              [email protected]

  Revision History
  Revision v4.10 July 3, 2000 Revised by: vv

  This document attempts to answer basic questions on how to set up your
  Linux box to serve as a DHCP server or a DHCP client.
    _________________________________________________________________

  Table of Contents
  1. [1]Introduction

       1.1. [2]Standard Disclaimer
       1.2. [3]New Versions of this Document
       1.3. [4]Feedback
       1.4. [5]Contributors
       1.5. [6]Copyright Information

  2. [7]DHCP protocol
  3. [8]Client Setup

       3.1. [9]Downloading the client daemon (dhcpcd)
       3.2. [10]Slackware
       3.3. [11]RedHat 6.x and Mandrake 6.x
       3.4. [12]RedHat 5.x
       3.5. [13]RedHat 4.x and Caldera OpenLinux 1.1/1.2
       3.6. [14]Debian
       3.7. [15]LinuxPPC and MkLinux
       3.8. [16]Tying it all together
       3.9. [17]Various notes
       3.10. [18]Troubleshooting
       3.11. [19]Alternative DHCP client (ISC dhclient)

  4. [20]DHCP Server Setup

       4.1. [21]DHCP server for UNIX
       4.2. [22]DHCP server configuration
       4.3. [23]Options for DHCPd
       4.4. [24]Starting the server
       4.5. [25]Other interesting documents

1. Introduction

1.1. Standard Disclaimer

  No liability for the contents of this documents can be accepted. Use
  the concepts, examples and other content at your own risk. As this is
  a new edition of this document, there may be errors and inaccuracies,
  that may of course be damaging to your system. Proceed with caution,
  and although this is highly unlikely, I don't take any responsibility
  for that.

  Also bear in mind that this is NOT official information. Much content
  in this document are assumptions, which appear to work for people. Use
  the information at your own risk.
    _________________________________________________________________

1.2. New Versions of this Document

  New versions of this document are available from

  [26]http://www.oswg.org/oswg-nightly/DHCP.html

  Following translations of the DHCP mini-HOWTO are available:

    * Chinese - [27]http://www.linux.org.tw/CLDP/mini/DHCP.html
    * Japanese - [28]http://www.linux.or.jp/JF/JFdocs/DHCP.html
    * Spanish -
      [29]ftp://cuates.pue.upaep.mx/pub/linux/LuCAS/DHCP-mini-Como/

  Permission is hereby granted to all individuals who want to translate
  the document into their own language. I would only ask that you
  provide a link back to this document and inform me of a URL to your
  translation so I can include a link to it.
    _________________________________________________________________

1.3. Feedback

  Feedback is most certaintly welcome for this document. Without your
  submissions and input, this document wouldn't exist. So, please post
  your additions, comments and criticisms to
  <[30][email protected]>.
    _________________________________________________________________

1.4. Contributors

  This document has been modified from the original version by Paul
  Makeev.

  The following people have contributed to this mini-HOWTO.

    * Heiko Schlittermann
    * Jonathan Smith
    * Dan Khabaza
    * Hal Sadofsky
    * Henrik Stoerner
    * Paul Rossington
    * numerous others
    _________________________________________________________________

1.5. Copyright Information

  This document is copyrighted (c) 1998 Vladimir Vuksan and distributed
  under the terms of the OpenContent License (OPL). Full text of the
  license can be found at

  [31]http://www.opencontent.org/opl.shtml
    _________________________________________________________________

2. DHCP protocol

  DHCP is Dynamic Host Configuration Protocol. It is used to control
  vital networking parameters of hosts (running clients) with the help
  of a server. DHCP is backward compatible with BOOTP. For more
  information see RFC 2131 (old RFC 1541) and other. (See Internet
  Resources section at the end of the document). You can also read
  [32]http://web.syr.edu/~jmwobus/comfaqs/dhcp.faq.html.

  This mini-HOWTO covers both the DHCP _SERVER_ daemon as well as DHCP
  _CLIENT_ daemon. Most people need the client daemon which is used by
  workstations to obtain network information from a remote server. The
  server daemon is used by system administrators to distribute network
  information to clients so if you are just a regular user you need the
  _CLIENT_ daemon.
    _________________________________________________________________

3. Client Setup

  Currently there are three different DHCP client programs for Linux,
  dhcpcd, pump and dhclient. This mini-HOWTO deals primarily with
  dhcpcd.
    _________________________________________________________________

3.1. Downloading the client daemon (dhcpcd)

  Depending on your distribution you might have to download the DHCP
  client daemon. If you want to compile it from the source you package
  you need is called dhcpcd and the current version is 1.3.18. It is
  maintained by Sergei Viznyuk <[33][email protected]> and today it
  comes as a binary package with most distributions.

  dhcpcd source can be downloaded from following locations

    * [34]ftp://ftp.phystech.com/pub/ (Primary site)
    * [35]http://www.cps.msu.edu/~dunham/out/

  Then follow the instructions below. They should be the same.
    _________________________________________________________________

3.2. Slackware

  You can download the latest copy of the DHCPcd from any Metalab mirror
  or following:

    * [36]ftp://metalab.unc.edu/pub/Linux/system/network/daemons
    * [37]ftp://ftp.phystech.com/pub/ (Primary site)

  Download the latest version of dhcpcd.tar.gz.

    * Unpack it
      tar -zxvf dhcpcd-1.3.18pl1.tar.gz
    * cd into the directory and make dhcpcd
      cd dhcpcd-1.3.18pl1
      make
    * Install it (you have to run the following command as root)
      make install

  This will create the directory /etc/dhcpc where DHCPcd will store the
  DHCP information and dhcpcd file will be copied into /usr/sbin.

  In order to make the system initialize using DHCP during boot type:

  cd /etc/rc.d

  mv rc.inet1 rc.inet1.OLD

  This will move the old network initialization script into
  rc.inet1.OLD. You now need to create the new rc.inet1 script.
  Following code is all you need:
#!/bin/sh
#
# rc.inet1      This shell script boots up the base INET system.

HOSTNAME=`cat /etc/HOSTNAME` #This is probably not necessary but I
                            #will leave it in anyways

# Attach the loopback device.
/sbin/ifconfig lo 127.0.0.1
/sbin/route add -net 127.0.0.0 netmask 255.0.0.0 lo

# IF YOU HAVE AN ETHERNET CONNECTION, use these lines below to configure the
# eth0 interface. If you're only using loopback or SLIP, don't include the
# rest of the lines in this file.

/usr/sbin/dhcpcd

  Save it and reboot your computer.

  When you are finished go the [38]last step.
    _________________________________________________________________

3.3. RedHat 6.x and Mandrake 6.x

  DHCPcd configuration under RedHat 6.0+ is really easy. All you need to
  do is start the Control Panel by typing control-panel.

    * Select "Network Configuration"
    * Click on Interfaces
    * Click Add
    * Select Ethernet
    * In the Edit Ethernet/Bus Interface select "Activate interface at
      boot time" as well as select "DHCP" as "Interface configuration
      protocol"

  Please note that in RedHat 6.x Redhat as default includes a DHCP
  client called pump instead of above mentioned dhcpcd. CD-ROM does
  include dhcpcd RPM so if you have no luck with pump try with dhcpcd.
  After you install dhcpcd (e.g. rpm -i dhcpcd-1.3.17pl2-1.i386.rpm) you
  will have to make some [39]changes.

  Additional notes from Alexander Stevenson
  <[40][email protected]>:

  I had no luck with DHCPcd. What finally worked for me was "pump",
  which comes with Linux Mandrake 6.0 (and so I assume it is included
  with RedHat as well). The command I used was:

  pump -i eth0 -h hostname

  It didn't matter what "hostname" was, but without it the server would
  not respond.

  I then changed the line in my /sbin/ifup script to reflect the change;
  the default version does not have the -h switch, and so didn't work
  for me.

  Basically, if you're using linuxconf, and after setting the adapter to
  "DHCP" it still doesn't work, try adding a "-h hostname" to the pump
  line in the /sbin/ifup script. My script now looks like this:
..
if [ -n "$PUMP" ]; then
   echo -n "Determining IP information for $DEVICE..."
   if /sbin/pump -i $DEVICE -h hostname; then
       echo " done."
   else
       echo " failed."
       exit 1
   fi
else ...

  That is it. Reboot your machine or type /sbin/ifup eth0 on the command
  line.
    _________________________________________________________________

3.4. RedHat 5.x

  DHCPcd configuration under RedHat 5.0+ is really easy. All you need to
  do is start the Control Panel by typing control-panel.

    * Select "Network Configuration"
    * Click on Interfaces
    * Click Add
    * Select Ethernet
    * In the Edit Ethernet/Bus Interface select "Activate interface at
      boot time" as well as select "DHCP" as "Interface configuration
      protocol"

  When you are finished go the [41]last step.
    _________________________________________________________________

3.5. RedHat 4.x and Caldera OpenLinux 1.1/1.2

  DHCPcd is included in the standard RedHat distribution as an RPM and
  you can find it on your distribution's CD-ROM in RPMS directory or you
  can download it from:

  [42]ftp://ftp.redhat.com/pub/redhat/redhat-4.2/i386/RedHat/RPMS/dhcpcd
  -0.6-2.i386.rpm

  Install it with rpm -i dhcpcd-0.6-2.i386.rpm.

  Alternatively you can compile your own version by following the steps
  outlined in the [43]Slackware.

  The following information was provided to me by nothing
  <[44][email protected]>.

    Removed my static ip and name from /etc/resolv.conf. However, I did
    leave in the search line and my two nameserver lines (for some
    reason my dhcpcd never creates a /etc/dhcpc/resolv.conf, so I have
    to use a static /etc/resolv.conf).

    In /etc/sysconfig/network I removed the HOSTNAME and GATEWAY
    entries. I left the other entries as is (NETWORKING, DOMAINNAME,
    GATEWAYDEV).

    In /etc/sysconfig/network-scripts/ifcfg-eth0 I removed the IPADDR,
    NETMASK, NETWORK, and BROADCAST entries. I left DEVICE and ONBOOT
    as is. I changed the BOOTPROTO line to BOOTPROTO=dhcp.

    Save the file. Reboot your computer.

  When you are finished go the [45]last step.
    _________________________________________________________________

3.6. Debian

  There is a deb package of DHCPcd (make sure it starts with dhcpcd) at:

  [46]http://ftp.debian.org/debian/dists/slink/main/binary-i386/net/

  Or, follow the [47]Slackware installation instructions.

  To unpack the deb package type dpkg -i
  /where/ever/your/debian/packages/are/dhcpcd*deb.

  It appears that there isn't a need for any DHCPcd configuration
  because:


  The dhcpcd package installs it's startup script as usual for debian
  packages in /etc/init.d/package_name, here as /etc/init.d/dhcpcd, and
  links this to the various /etc/rc?.d/ directories.

  --From: Heiko Schlittermann <[48][email protected]>

  The contents of the /etc/rc?.d/ dirs is then executed at boot time.

  If you don't reboot after installing you should consider starting the
  daemon manually: /etc/init.d/dhcpcd start.

  When you are finished go the [49]last step.
    _________________________________________________________________

3.7. LinuxPPC and MkLinux

  Following section has been written by R. Shapiro

  As of the "1999" (R5) release, Linuxppc is now almost completely
  compatible with Redhat 6, with one caveat (see below). In general the
  instructions are exactly the same as for the current release of
  [50]RedHat 6.x and Mandrake 6.x.

  The remaining problem is that Redhat 6 uses the 'pump' client for dhcp
  by default, and 'pump' doesn't work reliably in Linuxppc. To get
  around this, you should install the latest dhcpcd from Sergei Viznyuk,
  and then edit /sbin/ifup to use dhcpcd instead of pump.

  Change
if [ "$BOOTPROTO" = bootp -o "$BOOTPROTO" = dhcp ]; then
    PUMP=true
fi

if [ -n "$PUMP" ]; then

  with
if [  "$BOOTPROTO" = bootp ]; then
      echo " done."
    else
      echo " failed."
      exit 1
    fi
elif [ "$BOOTPROTO" = dhcp ]; then
    echo -n "Determining IP information for $DEVICE..."
    if /sbin/dhcpcd -d $DEVICE ; then
      if [ -f /etc/dhcpc/dhcpcd-${DEVICE}.exe ]; then
          /etc/dhcpc/dhcpcd-${DEVICE}.exe
      fi

  and a coresponding changes for ifdown. Change
if [ "$BOOTPROTO" = bootp -o "$BOOTPROTO" = dhcp ]; then
...
fi

  with
if [ "$BOOTPROTO" = bootp ]; then
fi

if [ "$BOOTPROTO" = dhcp ]; then
     if [ -f /var/run/dhcpcd-${DEVICE}.pid ]; then
             kill `cat /var/run/dhcpcd-${DEVICE}.pid`
             rm -f /var/run/dhcpcd-${DEVICE}.pid
     fi
fi

  A working ppc rpm for dhcpcd is included on the Linuxppc 1999 cd; a
  slightly later rpm is available in the contrib directory on
  [51]ftp://ftp.linuxppc.org/. Sources, which compile out of the box in
  Linuxppc 1999, are available from
  [52]ftp://ftp.phystech.com/pub/dhcpcd-1.3.17-pl9.tar.gz.
    _________________________________________________________________

3.8. Tying it all together

  After your machine reboots your network interface should be
  configured. Type: ifconfig.

  You should get something like this:
         lo        Link encap:Local Loopback
         inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
         UP BROADCAST LOOPBACK RUNNING  MTU:3584  Metric:1
         RX packets:302 errors:0 dropped:0 overruns:0 frame:0
         TX packets:302 errors:0 dropped:0 overruns:0 carrier:0 coll:0

eth0      Link encap:Ethernet  HWaddr 00:20:AF:EE:05:45
         inet addr:24.128.53.102  Bcast:24.128.53.255  Mask:255.255.254.0
         ^^^^^^^^^^^^^^^^^^^^^^^
         UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
         RX packets:24783 errors:1 dropped:1 overruns:0 frame:1
         TX packets:11598 errors:0 dropped:0 overruns:0 carrier:0 coll:96
         Interrupt:10 Base address:0x300

  If you have some normal number under inet addr you are set. If you see
  0.0.0.0 don't despair, it is a temporary setting before dhcpcd
  acquires the IP address. If even after few minutes you are seeing
  0.0.0.0 please check out [53]Troubleshooting. DHCPcd is a daemon and
  will stay running as long as you have your machine on. Every three
  hours it will contact the DHCP server and try to renew the IP address
  lease. It will log all the messages in the syslog (on Slackware
  /var/adm/syslog, RedHat/OpenLinux /var/log/syslog).

  One final thing. You need to specify your nameservers. There are two
  ways to do it, you can either ask your provider to provide you with
  the addresses of your name server and then put those in the
  /etc/resolv.conf or DHCPcd will obtain the list from the DHCP server
  and will build a resolv.conf in /etc/dhcpc.

  I decided to use DHCPcd's resolv.conf by doing the following:

  Back up your old /etc/resolv.conf: mv /etc/resolv.conf
  /etc/resolv.conf.OLD

  If directory /etc/dhcpc doesn't exist create it: mkdir /etc/dhcpc

  Make a link from /etc/dhcpc/resolv.conf to /etc/resolv.conf: ln -s
  /etc/dhcpc/resolv.conf /etc/resolv.conf

  If that doesn't work try this (fix suggested by
  <[54][email protected]> with a little amendment by Henrik
  Stoerner):

  This last step I had to perform only because my dhcpcd doesn't create
  an /etc/dhcpc/resolv.conf. In /etc/sysconfig/network-scripts/ifup I
  made the following changes (which are a very poor hack, but they work
  for me):
elif [ "$BOOTPROTO" = dhcp -a "$ISALIAS" = no ]; then
   echo -n "Using DHCP for ${DEVICE}... "
   /sbin/dhcpcd -c /etc/sysconfig/network-scripts/ifdhcpc-done ${DEVICE}
   echo "echo \$$ > /var/run/dhcp-wait-${DEVICE}.pid; exec sleep 30" | sh

   if [ -f /var/run/dhcp-wait-${DEVICE}.pid ]; then
       ^^^^
       echo "failed."
       exit 1

  I changed to:
elif [ "$BOOTPROTO" = dhcp -a "$ISALIAS" = no ]; then
   echo -n "Using DHCP for ${DEVICE}... "
   /sbin/dhcpcd
   echo "echo \$$ > /var/run/dhcp-wait-${DEVICE}.pid; exec sleep 30" | sh

   if [ ! -f /var/run/dhcp-wait-${DEVICE}.pid ]; then
       ^^^^^^
      echo "failed."
      exit 1

    Note: Notice the ! (bang) in if [ ! -f
    /var/run/dhcp-wait-${DEVICE}.pid ];

  Now sit back and enjoy :-).
    _________________________________________________________________

3.9. Various notes

  Following step(s) are not necessary but might be useful to some
  people:

   a. If you need network connectivity only occasionally you can start
      dhcpcd from the command line (you have to be root to do this)
      with: /usr/sbin/dhcpcd.
      When you need to down (turn off) the network type /usr/sbin/dhcpcd
      -k.
    _________________________________________________________________

3.10. Troubleshooting

  If you have followed the steps outlined above and you are unable to
  access the network there are several possible explanations:
    _________________________________________________________________

3.10.1. Your network card is not configured properly

  During the boot up process your Linux will probe your network card and
  should say something along these lines:
eth0: 3c509 at 0x300 tag 1, 10baseT port, address  00 20 af ee 11 11, IRQ 10.
3c509.c:1.07 6/15/95 [email protected]

  If a message like this doesn't appear your ethernet card might not be
  recognized by your Linux system. If you have a generic ethernet card
  (a NE2000 clone) you should have received a disk with DOS utilities
  that you can use to set up the card. Try playing with IRQs until Linux
  recognizes your card (IRQ 9,10,12 are usually good).
    _________________________________________________________________

3.10.2. Your DHCP server supports RFC 1541/My DHCP server is Windows NT

  Try running dhcpcd by typing dhcpcd -r.

  Use ifconfig to check if your network interface is configured (wait
  few seconds for the configuration process, initally it will say
  Inet.addr=0.0.0.0)

  If this solves your problem add the "-r" flag to the boot up scripts,
  ie: instead of /sbin/dhcpcd you will have /sbin/dhcpcd -r.

  For example under RedHat edit script
  /etc/sysconfig/network-scripts/ifup and change the following:
       IFNAME=$[ {DEVICE} \
       "/sbin/dhcpcd -r -c /etc/"- etc etc.
    _________________________________________________________________

3.10.3. During bootup I get error message "Using DHCP for eth0 ... failed"
but my system works fine.

  You are most likely using RedHat and you haven't followed instructions
  carefully :-). You are missing the ! (bang) in one of the if
  statements. Jump [55]here and check how to fix it.
    _________________________________________________________________

3.10.4. My network works for few minutes and then stops responding

  There are some reports of gated (gateway daemon) screwing up routing
  on Linux boxes which results in problem described above. Check if
  gated is running with: ps -auxww | grep gate.

  If it is try removing it with RedHat's RPM manager or removing the
  entry in /etc/rc.d/.
    _________________________________________________________________

3.10.5. My ethernet card is recognized during boot up but I still get "NO
DHCPOFFER" message in my logs. I also happen to have a PCMCIA ethernet card.

  You need to make sure that you have the 10BaseT port ("phone" plug) on
  your network card activated. Best way to verify it is to check what
  kind of connector your card is configured for during bootup e.g.
eth0: 3c509 at 0x300 tag 1, 10baseT port, address  00 20 af ee 11 11, IRQ 10.
                           ^^^^^^^^^^^^
3c509.c:1.07 6/15/95 [email protected]

  I have received reports of laptop users having this kind of problems
  due to the PCMCIA utilities (specifically ifport) that would set the
  connector type to 10Base2 (thinnet). You have to make sure you use
  10BaseT for your connection. If you are not reconfigure the card and
  restart the computer.
    _________________________________________________________________

3.10.6. My DHCP client broadcasts requests but no one answers (Contributed
by Peter Amstutz)

  On some systems, you need to include some hostname for your machine as
  part of the request. With dhcpcd, do this with dhcpcd -h foohost
  Probably the hostname wanted will be your account username on the
  network.
    _________________________________________________________________

3.10.7. I have followed all the steps but still my machine is not able to
connect

  The cable modem will usually memorize the ethernet address of your
  network card so if you connect a new computer or switch network cards
  you will somehow have to "teach" your cable modem to recognize the new
  computer/card. Usually you can turn of the modem and bring it back up
  while computer is on or you will have to call tech support and tell
  them that you have changed a network card in the computer.

  You have firewall rules (ipfwadm rules) that disallow port 67/68
  traffic used by DHCP to distribute configuration info. Check your
  firewall rules carefully.
    _________________________________________________________________

3.10.8. I have MediaOne Express service and I still can't connect.

  It appears that MediaOne has been using adding some things to DHCP
  that shouldn't be there. Supposedly this is not a problem anymore but
  if you experience outages check for these things. If you are (un)lucky
  to have Windows NT on your machine if you go into Event Viewer you
  will see a warning like this:
DHCP received an unknown option 067 of length 005. The raw option data is
given  below.

0000: 62 61 73 69 63            basic

  If this is the problem go to [56]ftp://vanbuer.ddns.org/pub/ and
  either download a binary or get the source for the change.
    _________________________________________________________________

3.11. Alternative DHCP client (ISC dhclient)

  If you have not had success getting your Linux connection running with
  the dhcpcd you might want to try ISC dhclient. dhclient comes with the
  DHCP distribution from ISC which includes both a DHCP client and a
  DHCP server. Instructions on how to get and compile the DHCP
  distribution can be found [57]here. When you are done with it please
  return to this section to configure the client.

    Note: Following information has been provided by Ted Lemon
    <[58][email protected]> one of the authors of dhclient.

  With the current version of the DHCP client, you don't actually need a
  dhclient.conf. All you have to do is invoke dhclient e.g.:
  /sbin/dhclient.

  This will configure all broadcast interfaces. If this doesn't work or
  you want to specify only one interface create a /etc/dhclient.conf
  file with this example configuration.
interface "eth0" {
 send dhcp-client-identifier 1:xx:xx:xx:xx:xx:xx;
 send dhcp-lease-time 86400;
}

  Here we assume that the ethernet interface is eth0. If not change
  accordingly. Also replace xx:xx:xx:xx:xx with your ethernet address.
  This dhclient.conf makes the client look more like a Win95 client.
    _________________________________________________________________

4. DHCP Server Setup

4.1. DHCP server for UNIX

  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

  [59]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.
    _________________________________________________________________

4.2. DHCP server configuration

  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:
255.255.255.255 all-ones

  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.
    _________________________________________________________________

4.3. Options for DHCPd

  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 ( [60]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:

  [61]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.
    _________________________________________________________________

4.4. Starting the server

  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)
/usr/sbin/dhcpd

  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.
/usr/sbin/dhcpd eth1

  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
/usr/sbin/dhcpd -d -f

  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.
/etc/rc.d/rc.local
    _________________________________________________________________

4.5. Other interesting documents

  Linux Magazine has a pretty good article in their April issue called
  [62]Network Nirvana: How to make Network Configuration as easy as DHCP
  that discusses the set up for DHCP.

References

  1. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN17
  2. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN19
  3. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN24
  4. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN41
  5. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN45
  6. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN64
  7. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN69
  8. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN74
  9. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN77
 10. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#SLACKWARE
 11. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#REDHAT6
 12. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN162
 13. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN179
 14. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#DEBIAN
 15. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN226
 16. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#NAMESERVER
 17. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN289
 18. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#TROUBLESHOOTING
 19. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN351
 20. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN365
 21. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#DHCPSERVER
 22. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN378
 23. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN399
 24. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN418
 25. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#AEN436
 26. http://www.oswg.org/oswg-nightly/DHCP.html
 27. http://www.linux.org.tw/CLDP/mini/DHCP.html
 28. http://www.linux.or.jp/JF/JFdocs/DHCP.html
 29. ftp://cuates.pue.upaep.mx/pub/linux/LuCAS/DHCP-mini-Como/
 30. mailto:[email protected]
 31. http://www.opencontent.org/opl.shtml
 32. http://web.syr.edu/~jmwobus/comfaqs/dhcp.faq.html
 33. mailto:[email protected]
 34. ftp://ftp.phystech.com/pub/
 35. http://www.cps.msu.edu/~dunham/out/
 36. ftp://metalab.unc.edu/pub/Linux/system/network/daemons
 37. ftp://ftp.phystech.com/pub/
 38. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#NAMESERVER
 39. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#LINUXPPC-RH6
 40. mailto:[email protected]
 41. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#NAMESERVER
 42. ftp://ftp.redhat.com/pub/redhat/redhat-4.2/i386/RedHat/RPMS/dhcpcd-0.6-2.i386.rpm
 43. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#SLACKWARE
 44. mailto:[email protected]
 45. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#NAMESERVER
 46. http://ftp.debian.org/debian/dists/slink/main/binary-i386/net/
 47. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#SLACKWARE
 48. mailto:[email protected]
 49. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#NAMESERVER
 50. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#REDHAT6
 51. ftp://ftp.linuxppc.org/
 52. ftp://ftp.phystech.com/pub/dhcpcd-1.3.17-pl9.tar.gz
 53. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#TROUBLESHOOTING
 54. mailto:[email protected]
 55. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#ERROR3
 56. ftp://vanbuer.ddns.org/pub/
 57. file://localhost/export/sunsite/users/gferg/howto/00_DHCP.html#DHCPSERVER
 58. mailto:[email protected]
 59. ftp://ftp.isc.org/isc/dhcp/
 60. http://www.kde.org/
 61. ftp://ftp.us.kde.org/pub/kde/unstable/apps/network/
 62. http://www.linux-mag.com/2000-04/networknirvana_01.html

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