

dhcrelay(8)                                           dhcrelay(8)


NNAAMMEE
       dhcrelay - Dynamic Host Configuration Protocol Relay Agent

SSYYNNOOPPSSIISS
       ddhhccrreellaayy [ --pp _p_o_r_t ] [ --dd ] [ --qq ] [ --ii _i_f_0 [ ......  --ii  _i_f_N
       ] ] _s_e_r_v_e_r_0 [ _._._._s_e_r_v_e_r_N ]

DDEESSCCRRIIPPTTIIOONN
       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.

OOPPEERRAATTIIOONN
       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.

CCOOMMMMAANNDD LLIINNEE
       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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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p 67,  then
       the  relay  agent  will  listen on port 67 and transmit to
       port 68.   Transmissions to servers will be  sent  to  the
       same port number that it specified in the --p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


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dhcrelay(8)                                           dhcrelay(8)


       a foreground process, the --d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.


SSEEEE AALLSSOO
       dhclient(8), dhcpd(8), RFC2132, RFC2131.

AAUUTTHHOORR
       ddhhccrreellaayy((8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 hhttttpp::////wwwwww..vviixx..ccoomm//iisscc..  To learn
       more about Vixie Enterprises, see hhttttpp::////wwwwww..vviixx..ccoomm..


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