Date: Fri, 04 Aug 2006 18:15:47 +0200 From: Michal Mertl <mime@traveller.cz> To: Mario Lobo <mario.lobo@ipad.com.br> Cc: freebsd-hackers@freebsd.org Subject: Re: getting interface MAC addr from C Message-ID: <1154708147.3222.15.camel@genius.i.cz> In-Reply-To: <200608040759.49390.mario.lobo@ipad.com.br> References: <200608040759.49390.mario.lobo@ipad.com.br>
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Mario Lobo wrote:
> Hi;
>
> Would anyone have a tip on how to get the MAC from a C program?
>
> I tried:
>
> struct ifreq ifreq;
> unsigned char *hw;
>
> strcpy(ifreq.ifr_name, "rl0");
> ioctl(fd, SIOCGIFMAC, &ifreq);
> hw = ifreq.ifr_ifru.ifru_data; ????
This is probably very far from what you want. MAC stands here for MAC(4)
- e.g. security related stuff as opposed to something network (did you
read MAC as Media Access Control?).
I don't know it that is the easiest/right way to get this information
but you can use getifaddrs(3). Attached find a simple program which
prints out the interfaces and their MAC addresses using getifaddrs().
The code for getting the printable address is taken from function
fmt_sockaddr() from src/usr.bin/netstat/route.c.
You can also probably use SIOCGIFADDR with the right socket passed in as
fd or with sysctl(3) (int mib[] = { CTL_NET, AF_ROUTE, 0, AF_LINK,
NET_RT_IFLIST, 0}).
> but i don't know if this is right or, if it is, where to get the MAC from the
> structure. I doesn't issue any error compiling or running though.
>
> In linux i used:
>
> struct ifreq ifreq;
> unsigned char *hw;
>
> strcpy(ifreq.ifr_name, "rl0");
> ioctl(fd, SIOCGIFHWADDR, &ifreq);
> hw = ifreq.ifr_hwaddr.sa_data;
>
> Thanks,
>
> Mario
>
HTH
Michal
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