Strange thing with iptables

Alexey Toptygin alexeyt at
Thu Sep 9 16:33:06 CEST 2004

On Thu, 9 Sep 2004, Martin Josefsson wrote:

>> which looked like:
>> iptables -A FORWARD -s $machine/ -j ACCEPT
>> What I was surprised on is the netmask. Is this a feature or a bug? I mean
>> this is quite strange netmask for me.
> It's a feature :)
> It doesn't make the current code any more complicated.
> And ther are actually people using it to do weird stuff...

Do you mean that one can use arbitrary bitmasks wherever netfilter wants a 
netmask value?
So, one might select all IPs with the LSB set with


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