dhcrelay(8) - NetBSD Manual Pages

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dhcrelay(8)                                           dhcrelay(8)



NAME

       dhcrelay - Dynamic Host Configuration Protocol Relay Agent


SYNOPSIS

       dhcrelay [ -p port ] [ -d ] [ -q ] [ -i if0 [ ...  -i  ifN
       ] ] server0 [ ...serverN ]


DESCRIPTION

       The  Internet Software Consortium DHCP Relay Agent, dhcre-
       lay, provides a means for relaying DHCP and BOOTP requests
       from  a  subnet  to  which no DHCP server is directly con-
       nected to one or more DHCP servers on other subnets.


SYSTEM REQUIREMENTS

       You must have the Berkeley Packet Filter (bpf)  configured
       in  your  NetBSD  kernel.    You  must  have  at least one
       /dev/bpf* file for each broadcast network  interface  that
       is attached to your system.


OPERATION

       The  DHCP  Relay  Agent  listens  for DHCP requests on all
       interfaces attached to a host, unless one or  more  inter-
       faces  are specified on the command line with the -i flag.

       When a query is received, dhcrelay forwards it to the list
       of  DHCP  servers  specified on the command line.   When a
       reply is received, it is broadcast or unicast on the  net-
       work from whence the original request came.

       It  is  possible  to  specify a set of interfaces on which
       dhcrelay will listen, so that  if  dhcrelay  is  connected
       through  one  interface  to a network on which there is no
       DHCP server, but is connected on another  interface  to  a
       network on which there is a DHCP server, it will not relay
       DHCP and BOOTP requests from  the  network  on  which  the
       server exists to that server.   This is an imperfect solu-
       tion.


COMMAND LINE

       The names of the network interfaces that  dhcrelay  should
       attempt  to configure may be specified on the command line
       using the -i option.  If no interface names are  specified
       on  the  command  line  dhcrelay will identify all network
       interfaces, elimininating non-broadcast interfaces if pos-
       sible, and attempt to configure each interface.

       If  dhcrelay  should  listen  and transmit on a port other
       than the standard (port 67), the -p  flag  may  used.   It
       should  be  followed  by the udp port number that dhcrelay
       should use.  This is mostly useful for debugging purposes.
       If the -p flag is specified, the relay agent will transmit
       responses to clients at a port number that is one  greater
       than  the one specified - i.e., if you specify -p 67, then
       the relay agent will listen on port  67  and  transmit  to



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dhcrelay(8)                                           dhcrelay(8)


       port  68.    Transmissions  to servers will be sent to the
       same port number that it specified in the -p flag.

       Dhcrelay will normally run in the foreground until it  has
       configured  an  interface, and then will revert to running
       in the background.  To run force dhcrelay to always run as
       a  foreground  process,  the  -d flag should be specified.
       This is useful when running dhcrelay under a debugger,  or
       when running it out of inittab on System V systems.

       Dhcrelay  will normally print its network configuration on
       startup.  This can be annoying in a system startup  script
       - to disable this behaviour, specify the -q flag.

       The  name  of  at  least one DHCP server to which DHCP and
       BOOTP requests should be relayed must be specified on  the
       command line.



SEE ALSO

       dhclient(8), dhcpd(8), RFC2132, RFC2131.


AUTHOR

       dhcrelay(8)  has  been  written  for the Internet Software
       Consortium by Ted Lemon <mellon@fugue.com> in  cooperation
       with  Vixie Enterprises.  To learn more about the Internet
       Software Consortium, see http://www.vix.com/isc.  To learn
       more about Vixie Enterprises, see http://www.vix.com.





























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