radvd - 1:2.19-2.1 main

IPv6 has a lot more support for autoconfiguration than IPv4. But
for this autoconfiguration to work on the hosts of a network, the
routers of the local network have to run a program which answers
the autoconfiguration requests of the hosts.
.
On Linux this program is called radvd, which stands for Router
ADVertisement Daemon. This daemon listens to router solicitations (RS)
and answers with router advertisement (RA). Furthermore unsolicited
RAs are also sent from time to time.