Strange routing table.

[Gordon Messmer]

Erik P. Olsen wrote:
> My main box is an FC3 linux box wire coupled to a Linksys router WRT54G. 
> I have two laptops wireless coupled to the router. One laptop runs 
> Windows 2000 the other Windows XP. The laptops can ping all boxes but 
> the linux box can't ping the laptops.


Is your router assigning IPs from the same network to both the Linux 
host and the wireless-attached hosts?  If so, you can use tcpdump 
(install it if you need to) and make sure that the Windows hosts are 
responding to ARP requests.

As an example, if I want to observe the arp and ping to 172.20.111.6 
from my workstation (wanderlust), I might use this command:

# tcpdump arp or host 172.20.111.6

I could be more specific, but that will work.  Now, if I ping that host 
in another terminal, I see these three lines printed from tcpdump:

14:29:47.317821 arp who-has 172.20.111.6 tell wanderlust
14:29:47.317975 arp reply 172.20.111.6 is-at 00:11:11:74:ca:7b
14:29:47.317986 IP wanderlust > 172.20.111.6: icmp 64: echo request seq 0

The first two are examples of what you should see.  If you ping another 
host in the same IP network, your workstation should request the MAC 
address of the remote host.  If it doesn't reply, it's possible that 
your router isn't bridging broadcast traffic between the wired and 
wireless attached networks.  If *that* is the case, the best solution is 
to configure the router to assign different IP networks to hosts in each 
of the wired and wireless attached nets.