ipfw IP ranges

Darek Milewski darek at nyi.net
Wed Mar 9 08:16:39 PST 2005


Hi there,

trying to specify IP ranges in ipfw.  The man page is pretty brief in 
this respect, but I understand that I should be able to specify

allow tcp from any to 1.2.3.0/25{14-24} 3389

which should apply the rule to IP block of 1.2.3.14 through 1.2.3.24.  
However, I was just closing down 1.2.3.127 and noticed that a port that 
was closed was accessible.  Turns out the rule above was matching 
traffic going to 1.2.3.127:3389.

When running 'ipfw show' the allow from above is listed as

allow tcp from any to 1.2.3.0/25 3389

So it looks like my original syntax enabled the rule for the whole /25 
subnet.  Am I doing this wrong?  If so, how can I specify ranges 
explicitly, meaning not using smaller subnets.  IE: 1.2.3.14-27 instead 
of 1.2.3.14/28, which would not be very precise of a match.  Perhaps I 
should be using /24 istead of /25?

Thanks!


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