core/Common.php getIp() uses ip2long(). This only works for ipv4 addresses.
ipv6 addresses result in 0 (and are converted back as "0.0.0.0").
Unit tests should ensure these formats are handled:
MySQL bigint is 8 bytes and won't accommodate a 128 bit ipv6 address. So... we'll defer comment:2 for post-1.0.
The current proposal is:
(In ) fixes #1110 - warn if IPv6 address detected during Installation; handle IPv4 mapped addresses