dhcp subnet, different network relay.

[Simon Collyer]

This is what I see from dhcpdump

I assume I'll have to do something from the circuit-id option 82?

---------------------------------------------------------------------------

   TIME: 2013-04-09 14:27:01.858
     IP: 58.xxx.xxx.194 (b4:14:89:0:70:0) > 203.xxx.xxx.19 (0:c:29:41:32:53)
     OP: 1 (BOOTPREQUEST)
  HTYPE: 1 (Ethernet)
   HLEN: 6
   HOPS: 1
    XID: 4a36a5df
   SECS: 65535
  FLAGS: 7f80
CIADDR: 0.0.0.0
YIADDR: 0.0.0.0
SIADDR: 0.0.0.0
GIADDR: 58.xxx.xxx.194
CHADDR: a4:b1:e9:6c:10:34:00:00:00:00:00:00:00:00:00:00
  SNAME: .
  FNAME: .
OPTION:  53 (  1) DHCP message type         1 (DHCPDISCOVER)
OPTION:  55 (  6) Parameter Request List      1 (Subnet mask)
                                              51 (IP address leasetime)
                                              58 (T1)
                                              59 (T2)
                                               3 (Routers)
                                               6 (DNS server)

OPTION:  82 ( 17) Relay Agent Information
                   Circuit-ID    41:56:43:30:30:30:30:30:30:35:37:39:38:37:31
---------------------------------------------------------------------------



Quoting Simon Collyer <simon at collyer.id.au>:

> Hi all,
>
> Having a few issues with getting the dhcp server to act as a "proper" relay.
>
> Current setup or process is as follows:
>
>
> (home user) -> (wholesale) -> **DHCP transaction** --> (our DHCP server)
>    ^^---------------------------DHCP REPLY-----------------------^^
>
> So the endpoint customer, is trying to get a DHCP address which is passed
> through our wholesaler.  We then want to route a different range to  
> the customer than what we have seen the address as:
>
> Currently the config sits at:
>
>
> subnet 203.***.***.0 netmask 255.255.255.0 {
> }
> subnet 58.***.***.0 netmask 255.0.0.0 {
>         ## dhcp start  and end IP range ##
>         range 14.***.***.2 14.***.***.253;
>         option subnet-mask 255.255.255.0;     ## subnet
>         option broadcast-address 14.***.***.255; ## broadcast
>         option routers 14.***.***.254; ## router IP
>
> }
>
> subnet 14.***.***.0 netmask 255.255.255.0 {
>         ## dhcp start  and end IP range ##
>         range 14.137.118.2 14.137.118.253;
>         option subnet-mask 255.255.255.0;     ## subnet
>         option broadcast-address 14.137.118.255; ## broadcast
>         option routers 14.137.118.254; ## router IP
> }
>
> Obviously this does not work and we are seeing the dhcp request being proxied
> through to us from a different subnet than the one we want to lease out.
>
>
> DHCPDISCOVER from a4:b1:e9:6c:10:34 via 58.***.***.194: network  
> 58.***.***.0/24: no free leases
>
> I've change the configuration around and removed the 58.*** range,  
> but get the following:
>
> DHCPDISCOVER from a4:b1:e9:6c:10:34 via 58.***.***.194: unknown  
> network segment
>
>
> What do I need to change or do to allow any request coming through  
> to hand out what range I specify?
>
> Any thoughts, help would be appreciated.
>
> Have been through google, but their is nothing that matches *  
> similar* to what I need to do.  Perhaps I may not have had enough  
> coffee yet as well :-)
>
> //Simon
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