All networking stops!

[John Rowe <rowe@excc.ex.ac.uk>]

I am attempting to run ipfilter 4.1.14 on Scientific Linux 4.3 (a Redhat
Enterprise clone) with kernel 2.6.9. Ipfilter installed fine just as the
instructions and there's a loadable module. My ipf.conf file is just:

        block out quick from any to 144.173.229.6
        pass in all
        pass out all

If I run the command ipf -v -f /etc/ipf.conf before loading the ipfilter
module it complains:

        open device: No such device or address
        User/kernel version check failed
        2:ioctl(add/insert rule): Bad file descriptor
        3:ioctl(add/insert rule): Bad file descriptor
        1:ioctl(add/insert rule): Bad file descriptor
        block out quick from any to 144.173.229.6/32
        pass in all
        pass out all

The ipfilter module is not loaded and nothing happens.

If I manually load the ipfilter module ("modprobe ipfilter"), all
networking stops, even ping. If I then run the above ifp command I get:

        2:ioctl(add/insert rule): Bad address
        3:ioctl(add/insert rule): Bad address
        1:ioctl(add/insert rule): Bad address
        block out quick from any to 144.173.229.6/32
        pass in all
        pass out all
        
Networking is still dead until I use modprobe -r to remove the ipfilter
module.

FWIW worth, I have two ethernet cards and at the moment I am just trying
to ssh into the machine (which is fine when ipfilter is not running).

Any help would be enormously appreciated!

Thanks

John