dhcp relay - not working.

[Glenn Satchell]

>Date: Tue, 8 Aug 2006 17:09:31 -0700 (PDT)
>From: foomail123 <foomail123 at yahoo.com>
>Subject: dhcp relay - not working.
>To: dhcp-users at isc.org
>
>Hi,
>
>This is using rel: 3.0.4 on Redhat Linux: 6.x/x86
>
>I see select() being invoked but.. relay(..) routine
>is not being invoked. I am running through debugger 
>and get following output:
>
>
>omapi_one_dispatch (wo=0x0, t=0x0) at
>src/omapip_dispatch.c:399
>399             for (io = omapi_io_states.next; io; io
>= io -> next) {
>(gdb) p /x io
>$4 = 0x54430
>(gdb) p /x omapi_io_states
>$5 = {type = 0x535a8, refcnt = 0x1, handle = 0x0,
>outer = 0x0, inner = 0x0, next = 0x54430, readfd =
>0x0, writefd = 0x0, 
>  reader = 0x0, writer = 0x0, reaper = 0x0}
>(gdb) 
>(gdb) p /x io
>$4 = 0x54430
>(gdb) p /x omapi_io_states
>$5 = {type = 0x535a8, refcnt = 0x1, handle = 0x0,
>outer = 0x0, inner = 0x0, next = 0x54430, readfd =
>0x0, writefd = 0x0, 
>  reader = 0x0, writer = 0x0, reaper = 0x0}
>(gdb) b relay
>Breakpoint 5 at 0x17154: file src/dhcrelay.c, line
>363.
>(gdb) c
>Continuing.
>
>
>Any suggestions ?
>
>Thanks !

What are the command line parameters you are starting dhcrelay with?

Note there is a potential trap with specifying the interfaces to listen
on. You *must* specify not only the interface to listen for dhcp
requests but *also* replies from the dhcp server if that happens to be
a different interface. Usually the default behaviour (listen on all
interfaces) is the correct one.

This is from the dhcrelay man page:

     The -i flag can be used to specify the network interfaces on
     which  the  relay agent should listen.   In general, it must
     listen not only on those network interfaces to which clients
     are  attached, but also on those network interfaces to which
     the server (or  the  router  that  reaches  the  server)  is
     attached.

Also dhcrelay only works for interfaces like ethernet, token ring and
fddi (and a few others) but it does not work on PPP and other
non-broadcast interface types.

regards,
-glenn