[clug] detecting rogue dhcp servers

[Kim Holburn]

Yeah, I have been looking at dhcping (debian c version, not the perl 
version <http://c3rb3r.openwall.net/dhcping/>).

What I need is a simple program that sends out a broadcast, just like a 
machine waking up, a : "Uhhh, where am I, who am I, please someone, 
anyone give me an IP" type request.

I can't get dhcping to do this.

I have to specify server IP, the client IP before I get an answer.  I'm 
not sure why.  Perhaps putting in an IP of 255.255.255.255 doesn't 
cause dhcping to send a broadcast.  I haven't done much c programming 
of interfaces at this level, so I think I have to set some option to 
make it broadcast.

It has :
flag=1;
setsockopt(dhcp_socket,SOL_SOCKET,SO_BROADCAST,(char *)&flag, sizeof 
flag) < 0

but maybe I have to set something somewhere else.

Any of you guys a socket guru?

Kim

On 2005 Jan 19, , at 10:25 AM, Paul Hampson wrote:

> On Tue, Jan 18, 2005 at 04:02:03PM +1100, Kim Holburn wrote:
>> Does anyone know of software that detects "rogue" dhcp servers?
>
> Something like dhcpping (I think) can probably send out a
> DHCP request, and see what responses you get.
>
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