Device Busy

[Peter Clark]

Hello,

   I am installing a FreeBSD 6.1 i386 machine and using IPF. When I 
apply some variables to sysctl for IPF I end up with a device busy 
response.

the variables in question are:
net.inet.ipf.fr_tcpclosed=1
net.inet.ipf.fr_tcpclosewait=60
net.inet.ipf.fr_tcphalfclosed=300
net.inet.ipf.fr_tcpidletimeout=7200
net.inet.ipf.fr_tcplastack=20
net.inet.ipf.fr_tcptimeout=120
net.inet.ipf.fr_udptimeout=120

The problem occurs both on startup with these in sysctl.conf and if I 
try do enter it manually:

imap# sysctl net.inet.ipf.fr_tcpclosed=1
net.inet.ipf.fr_tcpclosed: 120
sysctl: net.inet.ipf.fr_tcpclosed: Device busy


These are the same variables that I have been using successfully on 
other versions of FreeBSD (5.x and 4.x) so I am inclined to think that I 
am missing something obvious in this latest version.
I am running: FreeBSD 6.1-RELEASE-p2
with: ipf: IP Filter: v4.1.8 (416)

Any pointers?


Thanks,

Peter