networking problem

I have two computers. Sheaf (192.168.0.2) runs Mandriva 2006, Porter
(192.168.0.3) runs Ubuntu 5.10.

They are connected to a NetGear Wireless ADSL router (model DG834G)
(192.168.0.3), by ethernet cables.

I can ping from sheaf to porter, but not from porter back to sheaf.

Both machines can go through the router to the internet.

Here are the routing tables:

root@porter:~# netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth0
(netstat on porter doesn't list lo, but the interface is configured OK)

[root@sheaf ~]# netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth1


I spent hours looking for traceroute on Ubuntu, before finding tracepath:

[root@sheaf ~]# tracepath porter
1: 192.168.0.2 (192.168.0.2) 0.348ms pmtu 1500
1: porter (192.168.0.3) 0.590ms reached
Resume: pmtu 1500 hops 1 back 1

root@porter:~# tracepath sheaf
1: 192.168.0.3 (192.168.0.3) 0.437ms pmtu 1500
1: no reply
2: no reply
3: no reply

I think that the problem is with routing through the router, not really on
the computers themselves.

I tried creating static routes on the router from one machine to the
other, and this changed nothing.

Can anybody explain to me what is wrong, so I can fix it, please?


Beef.

Are both Linux personal firewall working