Fixing nss-mdns for IPv6 linklocal scoped addresses

  Deuxième Année    Informatique 

The configuration

We are running FreeBSD 8.2-RELEASE with GENERIC kernel

nss_mdns is a port of nss-mdns for FreeBSD. It adds support for mDNS address resolution system-wide through the use of a name service switch plugin. Here is the simplest configuration:

• install avahi (mDNS implementation) and nss-mdns using ports

     # cd /usr/ports/net/avahi
     # make install
     # cd /usr/ports/dns/nss_mdns
     # make install

and make appropriate configuration changes

• in /etc/rc.conf

    # dbus_enable="YES"
    # avahi_daemon_enable="YES"

• in /etc/nsswitch.conf

    #hosts: files dns mdns

The problem

IPv6 is configured on all interfaces and no global prefix is defined. We only have linklocal addresses. mDNS resolution works fine, but ping6 fails miserably, even when specifying the outgoing interface.

   bsd1# RES_OPTIONS=inet6 getent hosts bsd2.local
   fe80::a00:27ff:fef4:c55d  bsd2.local
   bsd1# ping6 bsd2.local
   ping6: UDP connect: Device not configured
   bsd1# ping6 -I em0 bsd2.local
   ping6: UDP connect: Device not configured

Actually, this is not a routing problem, but a scope id problem.