[benou]

Very good idea!

And I love bloom filter too (and their more modern successor cuckoo filter) but I'd challenge the usecase you mention though: 1 million IPv4 is 4MB, and 16MB for IPv6. That's tiny, you're better off using some kind of hashtable, unless you have a fast and small memory, and then a slow and big memory (say embedded processor with small CPU cache and some DRAM).

Bloom filters are useful when your working set cannot fit in your fast memory, to allow you to go to the slow memory only for a small number of requests.

[IanCal]

The other use is when the cost of checking the set is high due to something like accessing a remote system. You can pull a small representation of the full set and only do a network request after when it's likely to succeed.