> From: itojun@iijlab.net
> Date: 1999-10-07 20:13:23 -0700
> To: der Mouse <mouse@Rodents.Montreal.QC.CA>
> Subject: Re: PPPoE?
> Cc: tech-net@netbsd.org
> In-reply-to: "07 Oct 1999 22:42:49
> -0400."<"199910080242.WAA00693"@Twig.Rodents.Montreal.QC.CA>
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>
>
> >And related to that, given an interface name, what API should I use to 
> >find its MAC address?  (I'm perfectly willing, for the moment, to 
> >assume it's an Ethernet interface, though it'd be nice to get an error 
> >rather than garbage if not.)  I'd really *like* to do an AF_LINK
> >SIOCGIFADDR, but it appears to be impossible to create an AF_LINK (or 
> >AF_UNSPEC) socket, and SIOCGIFADDR seems to get the address  
family from
> >the socket the ioctl is done on.
>
> 	I do not really recommend SIOCGIFADDR these days as there can be 
> 	multiple address assigned to an interface in a family
> 	(for AF_LINK it may be safe to assume that there's only one,  
but...)
>
> 	I think SIOCGIFCONF (then loop through the chain of addresses) 
> 	is the best one.

There is (?) also the sysctl() approach, documented in Stevens'  
UNPV12E tome (and code on his web site - www.kohala.com).   It  
depends on support in your particular kernel, but it's an alternative  
(and "more modern"?).

The mib setup is roughly

        mib[0] = CTL_NET;
        mib[1] = AF_ROUTE;
        mib[2] = 0;
        mib[3] = family;                /* only addresses of this  
family */
        mib[4] = NET_RT_IFLIST;
        mib[5] = flags;                 /* interface index, or 0 */


Regards,

Justin

--
Justin C. Walker, Curmudgeon-At-Large *
Institute for General Semantics       |
Manager, CoreOS Networking            | When crypto is outlawed,
Apple Computer, Inc.                  | Only outlaws will have crypto.
2 Infinite Loop                       |
Cupertino, CA 95014                   |
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