dhcpcd-discuss

On 16/02/2010 09:50, Roy Marples said the following:

Hi

> Hi
>
> On Tuesday 16 February 2010 06:12:00 Duncan Webb wrote:
> > My ISP is not replying to DHCP_DISCOVER messages from a 5.1.3 (and
> > 5.1.5) client.
> >
> > I first tried connecting the client to the ISPs cable modem but didn't
> > get an IP.
> >
> > Then the machine was connected to a DHCP server on the LAN and this
> > worked fine.
> >
> > Then a Windows machine was connected to the modem and it got an IP
> > address (this was the first time this machine was connected to the modem)
> >
> > Then I started to use tcpdump to trace what was happening and it showed
> > that the dhcpcd-5.1.3 client only sent four DHCP_DISCOVER packets. On
> > the other hand the Windows machine sent a discover, received an offer
> > sent a request and received an ACK.
> >
> > After much searching and trial and error I have not yet found a solution
> > for this problem. I suspect that the problem lies in the configuration
> > and an older dhcpcd client on another Linux box works correctly.
> >
> > Does anyone have any ideas what to try?
>
> You could use wireshark to work out what the difference is between dhcpcd and 
> Windows. Aside from a few options here and there, the main difference is that 
> Windows will send a ClientID and dhcpcd will not by default.
>
> You can enable ClientID in dhcpcd by putting the word clientid on it's own 
> line in /etc/dhcpcd.conf


I have tried this but without success.

I would not expect this to be important as the Linux box running ipcop 
works using the 1.3 version of dhcpcd.

The options I see in from the Windows box are:
message type = DHCP Discover
DHCP Auto-Configuration
Client identifier
Host Name
Vendor Class identifier = "MSFT 5.0"
Parameter Request List:
1 = Subnet Mask
15 = Domain Name
3 = Router
6 = Domain Name Server
44 = NetBIOS over TCP/IP Name Server
46 = NetBIOS over TCP/IP Node Type
44 = NetBIOS over TCP/IP Scope
31 = Perform Router Discover
33 = Static Route
249 = Private/Classless Static Route (Microsoft)
43 = Vendor-Specific Information
Option: (43) Vendor-Specific Information

What I see in the packet from the dhcpcd-5.1.3 is:
message type = DHCP Discover
Client identifier
Maximum DHCP Message Size = 1492
Vendor class identifier = "Linux 2.4.36 i686"
Host Name
Parameter Request List:
1 = Subnet Mask
33 = Static Route
3 = Router
6 = Domain Name Server
12 = Host Name
15 = Domain Name
28 = Broadcast Address
51 = IP Address Lease Time
58 = Renewal Time Value
59 = Rebinding Time Value

Other than the Maximum DHCP Message Size I don't see anything that is 
significant. The Vendor class identifier was copied from the ipcop box 
that I'm currently using as a firewall.

I'm seeing other DHCP messages in the tcpdump trace, so I reckon that 
the server is seeing my messages.

Any more ideas?

Thanks,
Duncan