Don't send RAs on interfaces without a link-local address.

Since the source address of the RAs must be the link-local address.

src/radv.c

@@ -288,7 +288,10 @@ static void send_ra_alias(time_t now, int iface, char *iface_name, struct in6_ad
       context->netid.next = &context->netid;
     }
 
-  if (!iface_enumerate(AF_INET6, &parm, add_prefixes))
+  /* If no link-local address then we can't advertise since source address of
+     advertisement must be link local address: RFC 4861 para 6.1.2. */
+  if (!iface_enumerate(AF_INET6, &parm, add_prefixes) ||
+      parm.link_pref_time == 0)
     return;
 
   /* Find smallest preferred time within address classes,