Hi,

Steps to duplicate:

1.) In an ipf.rules file you can place the following rule exactly as typed (with typo):

block in quick proto tcp from8.8.8.8/32 to any 


2.) load ipf with 'ipf -F -a -f /etc/ipf.rules' or similar:

# ipfstat -hi
empty list for ipfilter(in)
# ipfstat -ho
empty list for ipfilter(out)

# ipf -F -a -f /etc/ipf.rules 
syntax error error at "/", line 1


Expected result:  

ipf correctly reports a syntax error and does reload rules until the error is corrected.

Actual result: 

# ipfstat -hi 
2 block in quick proto tcp from any to any 
 

At this point the box is deaf to the world until the rule is removed, corrected, or ipf is flushed via console.