The problem is as follows:
I have two computers. In the first computer there are two ethernet-cards (A:eth0 and A:eth1). In the second computer ther is one ethernet-card (B:eth0). Interface A:eth1 is connected two a LAN, A:eth0 is connected to B:eth0. Each of these interfaces have different IP-numbers (10.10.5.15,10.10.5.16,10.10.5.17). The problem is that I want computer A two "bridge" eth0 to eth1 so computer B can talk to the LAN.
It might be possible to use the bridging utilities but I don't want that. The problem seems to be that my IP-numbers are in the same segment. Note that I'm not allowed two use IP-numbers other than thos given above.