Hi,
I setup the dnsmasq in debian squeeze as dhcp and dns server, for the debian host i assigned the static ip addresses, and configured the xp for dhcp.
Windows XP network can't acquire DHCP address from debian squeeze with this error:
this is the tcpdump output in debian for the xp network:

As this is a forum and walking you through the install process is long I suggest you look at the Debian sarge tutorial for DHCP and ask any questions you have then.
I will help you get it running.

Click here for the guide

The 254.169 address in your out put is APIPA Automatic Private IP Addressing. What computer has this mac -> Request from 00:07:e9:a8:ea:93 The command ifconfig -a will show the mac on Linux.
IF you have added the Linux DHCP server to your network that has a router then you should rest your router and turn DHCP off in your router if you are using one.
What does your network consist of ? Router ? Switch ?
On your XP clients run ipconfig /flushdns
Then ipconfig /Registerdns
On your windows clients you can check if your getting your address using ipconfig /release and ipconfig /renew.
Let me know how your doing.

Since you don't mention whether you have established network connectivity between server and client, I would check the firewall on the windows box and then on the server.

Can you set a static IP on the Windows system w/ the requisite default route and DNS server and see if that works?

That, and do you have anything else that connects via DHCP?

I imagine that tcpdump capture was taken from the DHCP server, which, of course, would indicate the request is getting there. Determining if your DHCP server is functional is paramount.

Thanks for the replies, the 00:07:e9:a8:ea:93 is the xp pc adapter MAC address, the two pc's network adapters are directly connected with each other with a network cable and i didn't use any router or switch, this is the dnsmasq.conf for the dnsmasq to work as dhcp server:
The 192.168.1.1 is the debian static ip address.
i did the ipconfig/fulshdns, then registerdns then realse and renew but the result was same above errors the xp show the message of " limited or no connectivity" and the ipconfig result is:
i did the static ip for the xp pc but the xp cannot share the internet connection from the debian, and the share folders with samba some how works. but i want i can plug any xp pc to the network cable and that can get the ip from the dhcp server and share the internet connection from the debian.
The windows firewall is disabled and debian shorewall firewall is configured for two interfaces.

Straight out of the dnsmasq Debian Wiki page:

From what I can tell from that little blurb, it should be listening on both interfaces of your Debian system without defining the interface. I'd define the interface you want to use anyhow.

Which leads us back to the question as to why this DHCP server isn't answering. It sounds like your Debian system is connected to whatever internet source you are using, which I'd imagine is providing a public IP address, thus shouldn't be a conflict.

Something I'd do to eliminate the firewall as the issue, is disconnect the ethernet cable on the public interface, and drop the firewall. If the DHCP lease is provided then, you'll know you need to look at your firewall.

I doubt it is a Windows related issue, but to check you could boot your Windows system off a Linux live CD to see if the problem persists.

Thanks again for the reply, The problem solved with the specifying the interface as:
Ok now the xp can get an ip from the Debian dhcp as:
but still the web browser in windows cannot open the web pages:
this is the dnsmasq log from the /var/log/syslog for the windows xp the web browser want to open the google website:
and this is the dnsmasq log from the /var/log/syslog for the debian that can open the google.com:
In the windows pc the quey just stopping in the:

Shams you said "the two pc's network adapters are directly connected with each other with a network cable and i didn't use any router or switch"
Are you using a cross over cable ?
If you are Using a regular networking cable it will not work.

Heh. You might want to reread the analysis of the activity shams has seen thus far then reconsider your question. Auto-MDIX tends to solve issues such as this.

Hint: it is impossible to get a tcpdump capture showing layer 3 traffic where layer 2 connectivity hasn't been established.

shams:

I'd recommend using nslookup on the Windows system to determine if it is resolving DNS requests properly. From what it looks like there is a request sent and a response received -- and it appears that an answer was sent. DNS resolution is the first thing I check as well when troubleshooting issues such as these because without it, nothing else will work properly. It does not, however, establish that proper routing has been established for traffic. Even if your Debian system has its DNS service configured properly, it might not be forwarding traffic.

Check the Windows system with nslookup, see if it is getting a response. Caching/forwarding DNS servers are rather simple, and there really isn't very much to define in order to set them up.

Once you establish that DNS resolution is working, you should see if you can ping google. Use tcpdump to see if it is reaching the connected interface on the Debian system. Use this:

If you see it arriving at that interface, then go to the public facing interface and run tcpdump on it, or just fire up two tcpdump sessions simultaneously in two terminals. If you see traffic exiting the public interface, but it is exiting at the 192.168.x.x address, you're not natting the traffic properly, and the problem resides with your firewall rules/configuration. If you don't see the traffic exit the public interface, you might not have packet forwarding set up:

Although I would think that Shorewall would handle setting the system up for ip forwarding. I really doubt you will have to set that manually.

My impression is that for whatever reason, Shorewall isn't forwarding the traffic. We'll see if that is the case when you report back.

Oh yeah - double check you're getting a default gateway on the Windows machine with the DHCP lease.

thanks for the reply devwatchdog, i enabled the packet forwarding in the shorewall.conf:
as well in the kernel from the /etc/sysctl.conf:
and as well now i did echo 1 > /proc/sys/net/ipv4/ip_forward.
The nslookup is working from windows:
but ping is not working:
and this is the tcpdump output from debian when pinging from windows:
locally can open the debian web server from the windows, with the web browser.
I disable the shorewall and this is the iptables policy:
but still cannot ping the google from the windows there is timedout as above.

I'd enable Shorewall and attempt to ping google.com again, but this time capture traffic on the public/external interface. It is established you're getting traffic on eth0. We need to check that it is attempting to exit on the other interface. If it isn't, your firewall is not configured correctly. If the traffic exits as the originating 192.168.1.x address, your NAT rules are not working.

As for Shorewall, I don't use it although believe I installed it a few years ago for a short while. At a glance, I would start looking at what it logs, and enable logging if it isn't doing it now.

This should help provide some direction as to where your problem might lie:

Taken from here.