Knoppix and nessus

I ran nessus against Knoppix last night and noted this:
. Warning found on port general/tcp

    The remote host uses non-random IP IDs, that is, it is
    possible to predict the next value of the ip_id field of
    the ip packets sent by this host.

    An attacker may use this feature to determine if the remote
    host sent a packet in reply to another request. This may be
    used for portscanning and other things.

Nessus scans against a SuSE box and a Red Hat box did not yield this
message. Is this characteristic of Debian or did Knopper make a mistake
in building his kernal?

George