Re: kernel network device interface/link encap
From: Bernd Eckenfels
Date: Tue Apr 12 2005 - 20:50:52 EST
In article <51c8a7be05041217453244f225@xxxxxxxxxxxxxx> you wrote:
> I need an explanation of what exactly the 'link encap' field returned
> by ifconfig means in relationship to an interface. Information about
> how to change it and where it comes from would be a tremendous help.
It returns the hardware family of the Interface. See:
if (ioctl(skfd, SIOCGIFHWADDR, &ifr) < 0)
memset(ife->hwaddr, 0, 32);
memcpy(ife->hwaddr, ifr.ifr_hwaddr.sa_data, 8);
ife->type = ifr.ifr_hwaddr.sa_family;
Normally you can't change it. Or only in some limited way (different
ethernet oncoding styles).
In case of tun interfaces it is IMHO changed by attaching it. Normally in
tun-mode the device is set up as PPP, in TAP mode it is set up as Ethernet.
In the unspec case I guess it is set up wrong, and this ImHO means the user
mode program is not matching the kernel version (i.e. expecting another
ioctl or device).
There is also a tunctl command, not sure if it helps you.
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