Re: Exim and IPv6 Help

[itojun@iijlab.net]

>So we are again in the area of IPv4-mapped addresses not supported under
>OpenBSD. NetBSD has a sysctl switch to enable this if I remember your
>previous mail right. What's wrong with this approach?

	- kernel code gets more complex and we cannot audit kernel code.
	- applications can still be tricked to do bad things. (think of FTP
	  bounce attacks on active mode FTP, with more complexity with IPv4
	  mapped address).  for more complete attack scenarios see my recent
	  posting to bugtraq.

	actually, I don't really like the switch we have in NetBSD.  it has
	certain brokenness in places like in6_pcbbind(), as well as possibility
	to get abused.

itojun