Re: dhcp script!

[Ron <ron () skullsecurity net>]

On 09/08/2009 08:26 AM, jah wrote:
> Hi Ron,
>
> I tried your script with the command above against a DrayTek Vigor 2800G
> and was surprised to find that it doesn't respond to DHCP Information.
> I then used --script-args dhcptype=DHCPREQUEST and got the following:
>
> Interesting ports on vigor (192.168.1.1):
> PORT   STATE SERVICE REASON
> 67/udp open  dhcps   script-set
> |  dhcp-inform:
> |   DHCP Message Type: DHCPACK
> |   Server Identifier: 192.168.1.1
> |   Renewal Time Value: 1090126080
> |   Rebinding Time Value: 4034200320
> |   IP Address Lease Time (client): 2163475200
> |   Subnet Mask: 255.255.255.0
> |   Router: 192.168.1.1
> |_  Domain Name Server: 212.159.6.9, 212.159.6.10
> MAC Address: 00:50:7F:D5:5E:30 (DrayTek)
>
> So it didn't respond with all the items of info requested of it, but
> there is at least some useful info.  Maybe the DHCPREQUEST should be the
> default request?
> Nice script.
>
> jah

Interesting. My Linksys router didn't have an issue with DHCPINFORM, but 
I think that's part of a newer standard. Maybe a lot of residential 
routers don't like it?

My concern about DHCPREQUEST is side effects -- does it reserve that IP 
address?

Can you try using DHCPDISCOVER instead of DHCPREQUEST and see if that works?

Another option is, I can send out DHCPINFORM by default, then try 
DHCPDISCOVER/DHCPREQUEST if that fails.

Ron

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