Man Linux: Main Page and Category List


       rdnssd - IPv6 Recursive DNS Server discovery Daemon


       rdnssd [-f] [-H merge-hook] [-r resolv-file] [-p pidfile] [-u username]


       rdnssd is a  daemon  program  providing  client-side  support  for  DNS
       configuration  using  the  Recursive  DNS  Server  (RDNSS)  option,  as
       described in RFC 5006.  Its purpose is to  supply  IPv6  DNS  resolvers
       through  stateless autoconfiguration, carried by Router Advertisements.

       rdnssd parses RDNSS options and  keeps  track  of  resolvers  to  write
       nameservers entries to a resolv.conf(5) configuration file. By default,
       it writes its own separate file, and may call an external hook to merge
       it  with the main /etc/resolv.conf. This is aimed at easing coexistence
       with   concurrent   daemons,    especially    IPv4    ones,    updating
       /etc/resolv.conf too.

       On Linux, since version 2.6.24, rdnssd takes advantage of a new netlink
       interface,  forwarding  RDNSS  options  validated  by  the  kernel   to
       userland.  Otherwise, it merely listens to all ICMPv6 traffic through a
       raw socket.


       -f or --foreground
              Do  not  detach  from  the  console.  Run  the  program  in  the

       -H merge-hook or --merge-hook merge-hook
              Execute  this  hook  whenever  resolv.conf  is  updated. If this
              option is not specified, then no hook will be called.

       -h or --help
              Display some help and exit.

       -p pidfile or --pidfile pidfile
              Override the location of the pidfile.

       -r resolv-file or --resolv-file resolv-file
              Set the path to the generated resolv.conf file.

       -u username or --user username
              Override the user that the program will run as. By  default,  it
              runs as nobody.

       -V or --version
              Display program version and license and exit.


              A basic merge hook shipped with rdnssd, to be called with the -H

              The  default  resolv.conf(5)  file  that   rdnssd   writes   its
              configuration to.

              The process-id file.


       rdnssd  does  not keep track of the lifetimes of the routers associated
       with some DNS resolvers, whereas it should to strictly comply with  RFC

       When  rdnssd uses a raw socket instead of the netlink kernel interface,
       it does not validate received Neighbor Discovery traffic  in  any  way.
       For  example,  it  will  always  consider Router Advertisement packets,
       whereas it should not if the host is configured as a router.  When  the
       netlink interface is used, such validation is done by the kernel.


       resolv.conf(5), rdisc6(8), ipv6(7)


       Pierre Ynard <linkfanel at>

       $Id: rdnssd.8-in 575 2007-12-29 21:55:43Z linkfanel $