Can I prevent IP Spoofing attacks with wireless WRTGs router?

Question

I think i'm under attack.
I have a WRTGs linksys router, which routes port 80 traffice to an apache webserver running bugzilla.
Scanning through the apache logs see a bunch of errors resulting from un-allowed accesses to bugzilla.  The odd thing is that the source ip address logged in these errors are all internal addresses which have been statically assigned.
For instance, a typical error in the errorlog looks like:
[Wed Jan 31 04:17:05 2007] [error] [client 192.168.1.49] client denied by server configuration: C:/Bugzilla/
The above entry was from just this morning, and was part of a cluster of about 200 errors.  At the time the log entry was made, I know there was nobody on the machine.
So, I think someone must be trying to hack my bugzilla from the outside using IP Spoofing.
I did a bit of research, which indicates that this sort of thing can be prevented by configuring the firewall to discard any packets coming in from the WAN that have internal LAN source or destination addresses.
And so my question.  Can I configure the WRTGS router to do this?  I took a look through the admin screens, and did not see anything like "get rid of all the packets that look like this". 
thanks in advance
dmc_lat47

Answer 1

You cannot modify the firewall rules with standard Linksys firmware. What you could do is install a third party firmware. Then you have direct access to Linux on the router and can configure firewall rules with iptables.
For 3rd party firmwares, which projects exists and on which hardware versions of the WRT54G they will work please read the wikipedia article on "wrt54".