Bug 28902

 >  <<On Thu,  8 Jun 2000 14:06:27 +0200 (CEST), sam@inf.enst.fr said:
 > 
 >  >      A FreeBSD box on a private network with IPv4 routes to local
 >  >      network only. No default route has been set, nor any route for
 >  >      the 224.0.0.0/8 addresses.
 > 
 >  Then your configuration is broken.  If you want to send multicasts,
 >  you MUST configure a route for them, end of story.
 > 
 >  This requirement has existed throughout the entire history of IP
 >  multicast under UNIX.
 
 Many bugs existed throughout the entire history of <whatever> under Unix
 until they get fixed. RFC1112 says:
 
  Second, for hosts that may be attached to more than one network, the
  service interface should provide a way for the upper-layer protocol
  to identify which network interface is be used for the multicast
  transmission.  Only one interface is used for the initial
  transmission; multicast routers are responsible for forwarding to any
  other networks, if necessary.  If the upper-layer protocol chooses
  not to identify an outgoing interface, a default interface should be
                                         +++++++++++++++++++++++++++++
  used, preferably under the control of system management.
  ++++
 
 (If I were dark side-inclined, I'd suggest lo0 :)
 
 Also, you mention "send". Let me further point out that the PR
 description begins with:
 
 >        When trying to join a multicast group with a
 >        IPPROTO_IP/ADD_MEMBERSHIP ioctl call on a IPv4 socket, FreeBSD
 
 That's not sending (even though what the PR originator really wants is
 to send). That's what RFC1112 describe as:
 
  However, before any datagrams destined to a particular
  group can be received, an upper-layer protocol must ask the IP module
  to join that group.  
 
 It goes on to say that
 
  The interface argument may be omitted on
  hosts that support only one interface.    
 
 and
 
  It is permissible to join the same group on more than one interface,
 
 >  Note that it would be an error for packets to be multicast out
 >  multiple interfaces simultaneously.  The definition of the multicast
 >  service model says that hosts MUST NOT do this; only a multicast
 >  router is permitted to send the same packet in multiple directions at
 >  once.
 
 It doesn't say "must not", though this is clearly the intent.
 
 -- 
 Daniel C. Sobral			(8-DCS)
 dcs@newsguy.com
 dcs@freebsd.org
 capo@the.secret.bsdconspiracy.net
 
 	wow regex humor... I'm a geek