[ILUG] Routing problem

[Kevin]

I am having problems with my Debian/Lenny firewall/routing box. The 
internet connection runs really, really slow. It does work - but its 
very slow.

My internal lan is 192.168.100.*
My DSL router is 192.168.1.254
My external nic (wireless) is 192.168.1.1
My internal nic is 192.168.100.1

I checked the routing table:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use 
Iface
192.168.100.0   *               255.255.255.0   U     0      0        0 eth0
192.168.1.0     *               255.255.255.0   U     0      0        0 
wlan0
default         192.168.1.254   0.0.0.0         UG    0      0        0 
wlan0


Ifconfig/iwconfig look OK. However if I run traceroute I get some odd 
results:

traceroute to an internal LAN address completes in 1 hop

traceroute to the DSL router 192.168.1.254 from the firewall box fails 
after about 30 hops - it should be 1 hop.

Running tracepath on the DSL box gives me:

server:/home/kevinphilp# tracepath 192.168.1.254
 1:  192.168.1.1 (192.168.1.1)                              1.218ms pmtu 
1500
 1:  no reply
 2:  no reply

On google I get the same
server:/home/kevinphilp# tracepath www.google.com
 1:  192.168.1.1 (192.168.1.1)                              0.950ms pmtu 
1500
 1:  no reply
 2:  no reply

Any thoughts welcome

Kevin.