How about this. Put your subnets in a hash table of the following form: 
%subnets = ( "$subnet1/$prefix_length1" => undef, "$subnet2/$prefix_le
+ngth2" => undef, ... );

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Then for each IP address, build a list of "$subnet/$prefix_length" pairs covering all the subnets it could theoretically belong to.

In reply to Re: finding if an ip is in a subnet by hazylife
in thread finding if an ip is in a subnet by AltGrendel

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