ipfw subnetting

[Ian Smith]

In freebsd-questions Digest, Vol 416, Issue 1, Message: 26
On Mon, 21 May 2012 10:06:12 +0100 Paul Macdonald <paul at ifdnrg.com> wrote:

 > can anyone suggest what i'm doing wrong here.
 > 
 > Desired:    drop everything from 180.0.0.0 to 180.255.255.255
 > 
 > ipfw -q add 137 deny all from 180.0.0.0/8 to any

t23# ipfw -q add 137 deny all from 180.0.0.0/8 to any
t23# ipfw show 137
00137    0       0 deny ip from 180.0.0.0/8 to any

So what doesn't work?  (apart from scattergun removal of small pieces of 
a whole lot of Asian countries, incl. Japan, Indonesia, Australia, .. :)

cheers, Ian