UPDATE: This problem is solved. The only thing I had to do was to run this on Ubuntu: echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp


Original problem:

  1. Amiga can ping Ubuntu
  2. Ubuntu can ping Amiga
  3. When Amiga tries to ping anything else, the packets are forwarded correctly to the destination.
  4. When the ping packets are to travel back, it doesn't work. In Wireshark it shows that the other computer asks "Who has 10.10.10.7? Tell 10.10.10.x".
  5. If I manually add Ubuntu as a route/gateway for Amiga at that other computer, it works: * route add -host 10.10.10.7 gw 10.10.10.207
  6. If this manual route is added on Router, the Amiga can now ping the rest of the intertubes.
  7. I have to add this route manually on each machine on the LAN that I want my Amiga to communicate with.

So, what I want to know is:

Can I somehow make a change on any of the machines Amiga, Ubuntu, or Router, that will make routing work for all machines on the LAN? Basically: When someone asks "Who has 10.10.10.7?", I want Ubuntu or Router to say "10.10.10.207 has that!".