Very short background info:

    ipfirewall is an IP packet filtering tool which is analogous to the
    packet filtering facilities provided by most commercial routers.
    Once the facility has been installed on a host computer, the system
    administrator defines a set of blocking filters and a set of forwarding
    filters.  The blocking filters determine which packets are to be accepted
    by the host.  The forwarding filters determine which packets are to
    be forwarded by the host.

There is a bug in ipfirewall v2.0 (and v2.0a) that can, in certain
circumstances, result in filters not being applied to packets as intended
by the system administrator.  User's of ipfirewall v2.0 (and v2.0a) should
seriously consider upgrading to this new version.

This version can be found in

    ftp://ftp.bsdi.com/contrib/networking/security/ipfirewall_v2.0b.shar.gz

or

    ftp://ftp.nebulus.net/pub/bsdi/security/ipfirewall_v2.0b.shar.gz

Alternatively, if you send me a request via e-mail, I can send it back to
you as a set of shar files (my e-mail address is danny@bouletfermat.ab.ca).

N.B. If you are a registered user of ipfirewall v2.* then I e-mailed the
bug fix to you on the day after the bug was reported.  This note is intended
for users of ipfirewall v2.0 (and v2.0a) who haven't registered themselves
(ipfirewall v2.* is distributed on a shareware basis).

-Danny

P.S. The v2.0b release also contains patches for installing ipfirewall on
a FreeBSD 2.0 system.  The release now includes patches for installing it
on BSD/OS v1.*, BSD/OS v2.0, NetBSD-current and FreeBSD 2.0.

P.P.S. I'm posting this to the NetBSD current-users mailing list because the
original ipfirewall v2.0 announcement was posted here and I'm trying to reach
as many unregistered users as practical.