Subject: Re: IPv4 multicast set/getsockopt, specifying interface index
To: None <>
From: Jason R Thorpe <>
List: tech-net
Date: 01/12/2001 20:01:34
On Sat, Jan 13, 2001 at 12:53:17PM +0900, wrote:

 > 	IPv4 multicast set/getsockopt uses interface address to identify
 > 	the interface.  this causes problem when you have the same IPv4
 > 	address on multiple interfaces (example: "unnumbered" p2p interface).
 > 	we need a way to specify interface by interface index instead.
 > 	also, if interface address changes after setsockopt(a, IP_MULTICAST_IF),
 > 	getsockopt(IP_MULTICAST_IF) will return the new address and it will
 > 	be harder for user program to guess which interface it is.

Oh, thank you!  This is something I need for some changes I've been
working on for mrouted(8).

        -- Jason R. Thorpe <>