Configure IPv6 Privacy Extensions for SLAAC, described in RFC4941.
If enabled, it makes the kernel generate a temporary IPv6 address in addition to the public one generated from MAC address via modified EUI-64. This enhances privacy, but could cause problems in some applications, on the other hand. The permitted values are: -1: unknown, 0: disabled, 1: enabled (prefer public address), 2: enabled (prefer temporary addresses).
Having a per-connection setting set to "-1" (unknown) means fallback to global configuration "ipv6.ip6-privacy".
If also global configuration is unspecified or set to "-1", fallback to read "/proc/sys/net/ipv6/conf/default/use_tempaddr".
Note that this setting is distinct from the Stable Privacy addresses that can be enabled with the "addr-gen-mode" property's "stable-privacy" setting as another way of avoiding host tracking with IPv6 addresses.