Invalid increment in DHCP6 server address range check
When computing the start IP for the 'available range' field, services_dhcpv6.php attempts to increment a colon-formatted v6 address:
$range_from = gen_subnetv6($ifcfgip, $ifcfgsn);
Since increment on a non-numeric value fails, range_from retains the un-incremented value.
#1 Updated by Daniel Becker over 5 years ago
Note that this is actually matches the behavior of the range checks that services_dhcpv6.php performs: The actual check uses the range from gen_subnetv6() to gen_subnetv6_max(), which does include the first (= all-zeroes host part) v6 address in the prefix.