[c-nsp] DHCP Proxy

[Peter Rathlev]

On Tue, 2015-01-20 at 09:06 +0100, Peter Rathlev wrote:
> On Tue, 2015-01-20 at 10:09 +0530, Ambedkar wrote:
> > I want to send the Proxy settings includes IP address, port number through
> > DHCP in cisco routers and switches.
> > 
> > Is it possible to send ?
> > If yes, How ??
> 
> Can you be a bit more precise? Do you want to forward DHCP requests on a
> non standard port, i.e. not 67/UDP? [...]

Sorry, misread your question. :-) Joshua seems to have it right.

According to Microsoft Technet:

  http://technet.microsoft.com/en-us/library/cc940962%28v=ws.10%29.aspx

the option 252 is a string in the format:

  http://<SecurityServerName>:<PortNumber>/wpad.dat

Configuration like this could thus work:

  ip dhcp pool 192.0.2.0/24
    [ other options and parameters ]
    option 252 ascii "http://192.0.2.50:1234/wpad.dat"
    exit
  !

Beware that some clients aren't asking for option 252 during the DORA
sequence and instead sends INFORMs some time after, as this message
seems to imply:

  https://lists.isc.org/pipermail/dhcp-users/2013-September/017193.html

As far as I know, in IOS you can't send options the client isn't asking
for in the REQUEST. (That is: You can't modifWhich means your clients
might not pick up the WPAD option at all.

-- 
Peter