autoconf

file: /proc/sys/net/ipv6/conf/interface/autoconf
variable: net.ipv6.conf.interface.autoconf
Official reference

Autoconfigure addresses using Prefix Information in Router Advertisements.

Functional default: enabled if accept_ra_pinfo is enabled. disabled if accept_ra_pinfo is disabled.

Nb: per interface setting (where “interface” is the name of your network interface); “all” is a special interface: changes the settings for all interfaces.

source