NAME    [Toc]    [Back]

     dhcp - configuring OpenBSD for DHCP

DESCRIPTION    [Toc]    [Back]

     The Dynamic Host Configuration Protocol (DHCP) allows  hosts
on a TCP/IP
     network to configure one or more network interfaces based on
information
     collected from a DHCP server in response to a DHCP  request.
This mechanism
 is often used, for example, by cable modem and DSL network providers
     to simplify network configurations  for  their  clients/customers.

     Information  typically  contained within a DHCP response includes an IP address
 for the interface,  subnet  mask,  broadcast  address,
router (gateway)
     listing,  domain  name  server  listing, and the interface's
MTU.

     To set up OpenBSD as a DHCP client:

           1.   For each interface that is to be  configured  via
DHCP, create a
                /etc/hostname.XXX  file  (where XXX is the interface's identifier,
  e.g.,  ep1)  that  starts  with   the   word
``dhcp'', optionally
                followed  by  additional  interface options.  See
hostname.if(5)
                for more  information  on  the  format  of  these
files.

                The  /etc/netstart  script  reads  each  of these
hostname files at
                boot-time and runs the  dhclient(8)  program  for
each interface
                that is to be configured via DHCP.

           2.      [Optional]    To    tweak    settings,    edit
/etc/dhclient.conf.  This
                file   is   shipped   with   the   system.    See
dhclient.conf(5) and
                dhclient(8) for details.

     To set up OpenBSD as a DHCP server:

           1.    Edit /etc/dhcpd.conf.  This file is shipped with
the system.
                See dhcpd.conf(5) and dhcpd(8) for details.

           2.   Edit  /etc/dhcpd.interfaces.   This  file  should
contain a list
                of  interfaces you wish to serve by dhcpd(8).  If
you have only
                one broadcast network interface or  you  wish  to
serve all interfaces,
  this step is not required.  Be sure to
leave this
                file empty (or even delete it)  if  this  is  the
case.

           3.   Edit /etc/rc.conf.local and set dhcpd_flags="-q".
This will
                cause OpenBSD to start  the  dhcpd(8)  daemon  at
boot-time and
                listen  for  DHCP  requests on the local network.
To start it
                manually, execute the following commands:

                      # touch /var/db/dhcpd.leases
                      # /usr/sbin/dhcpd -q [netif1 netif2 ...]

           4.   Ensure the kernel  has  been  compiled  with  BPF
(Berkeley Packet
                Filter)  support  and at least one /dev/bpf* file
exists per
                broadcast network interface that is  attached  to
the system.
                This is almost always the case and should only be
considered
                if all other troubleshooting options have failed.

     See  dhcpd(8)  for  information  on other available options.
Note, however,
     that most of the flags are useful only for debugging purposes.

FILES    [Toc]    [Back]

     /etc/dhcpd.conf        DHCP server configuration file
     /etc/dhcpd.interfaces   list of network interfaces served by
dhcpd(8)
     /etc/rc.conf.local     configuration file where  dhcpd_flags
must be set
     /etc/dhclient.conf     DHCP client configuration file
     /etc/hostname.XXX         interface-specific   configuration
files

SEE ALSO    [Toc]    [Back]

     dhclient.conf(5),       dhcpd.conf(5),       hostname.if(5),
dhclient(8), dhcpd(8)

OpenBSD      3.6                           July      8,      1999