Yes, I'm sure that they are good, I get a connection with these cables
from my machine.
Unfortunately I don't have any hub or something like that.
It does light up on the switch with both cables, with both cables
the light on the switch does flicker a bit... don't know if this is 
important.

I really know the difference between a crossover and a patch cable :)

You said, pinging is disabled by default. If my machine is connectet to 
the m0n0 by crossover cable, then I get a ping to it. Browsing to the 
webinterface doesn't work at all with both cables...

Seth Rothenberg wrote:

>Are you sure that all the cables you tried are good?
>
>Do you have any other test equipment available?
>eg, a hub, with or without an uplink....
>
>the PC engines should light up a port on the hub
>with one cable or the other.
>
>You didn't mention if you are knowledgable about
>cables.  You can check by eye if it is a crossover.
>If the orange and/or green are reversed from one
>end to the other, it is crossover.
>
>You can test 2 crossover cables with a coupler
>on a regular cable run.
>
>
>These are just some ideas to try...
>
>
>
>
>  
>