When I once used mod_asn on a host with IPv6 connectivity, I ran into a problem
with the PostgreSQL database server eating memory. The ip4r data type, implanted
throuth the postgresl-ip4r contrib extension, is IPv4 only, and I believe that it
has a bug when it gets queries with IPv6 addresses. What happened was that the
server ran fine for some time, but after a while it complained about an out of
memory situation. The kind of memory that it claimed to have ran out of was not
clearly identifiable; the error message didn't seem to make sense to me 100%.
Since the ASN database is Ipv4-only, I will commit a fix to mod_asn that will stop
it to send IPv6 addresses to the database. That should avoid the issue.
The issue should be (reported and) debugged separately with postgresql-ip4r. Also,
ways to extend postgresql-ip4r for Ipv6 would be interesting to discuss. Finally,
there might be an ASN database for IPv6 addresses in the future; and 32-bit AS
numbers are also coming soon (which is another change). 32-bit AS will supercede
(or supplement, first) the current 16-bit AS numbers.