Re: IPv6 has trouble assigning an interface

From: Pekka Savola
Date: Mon Apr 25 2005 - 16:05:11 EST

On Mon, 25 Apr 2005, Felix von Leitner wrote:
Here is an strace of some piece of code of mine:

setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [12884901889], 4) = 0
bind(3, {sa_family=AF_INET6, sin6_port=htons(8002), inet_pton(AF_INET6, "::", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 0
setsockopt(3, SOL_IPV6, IPV6_MULTICAST_LOOP, "\1", 1) = 0
sendto(3, "ncp-lowfat-1.2.2", 16, 0, {sa_family=AF_INET6, sin6_port=htons(8002), inet_pton(AF_INET6, "ff02::6e63:7030", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = -1 EADDRNOTAVAIL (Cannot assign requested address)

ff02 is a link-local multicast address. I've bound to ::. How can this
fail? link-local should always work, even if no routes are set and no
router has been found.

Umm.. link-local unicast and multicast both require that you specify the interface, because otherwise it's ambiguous -- how could the kernel know which interface should be used to send the packet?

Pekka Savola "You each name yourselves king, yet the
Netcore Oy kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
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