Patric, please elaborate what you have in mind by "subnet is wrong".
I'm typing this from another PC which has the subnet mask 255.255.255.0 and the same static IP, ISP gateway, DNS that I was trying to use with OpenBSD, and as this message proves, it routes fine. Is it the case that Mac OS X, Windows, Linux are too lax with "incorrect" subnet masks, while OpenBSD needs it to be more specific or what? Puzzled.