[PLUG] localhost

Terry Griffin griffint at pobox.com
Thu Dec 18 17:24:04 UTC 2008


On Thursday 18 December 2008 7:28 am, linux-yug wrote:
> On Wed, 2008-12-17 at 23:39 -0800, Terry Griffin wrote:
> > On Wednesday 17 December 2008 11:22 pm, linux-yug wrote:
> > > On Wed, 2008-12-17 at 23:00 -0800, drew wymore wrote:
> > > > You want to ping 127.0.0.1 which is the local loopback on the nic
> > >
> > > Well, I think you said the magic word loopback....  I do associate
> > > loopback with localhost.. but, does it loopback through the nic or not?
> > >
> > >
> > > Wondering.
> >
> > No physical NIC is associate with the loopback address. It goes through
> > a separate logical NIC named "lo", not the "eth0" or "wlan0" associated
> > with your physical NIC.
> >
> > Side point - With Linux, when pinging the host's own IP address, even
> > one that is associated with a physical NIC, the packets do not actually
> > go though the NIC. The kernel is smart enough to realize that the IP
> > address is it's own, and it shortcuts the packet's route.
> >
> > Terry
>
> I had to do an ifconfig  and actually look at lo, after you brought it
> up, to see it......After ignoring it for years.....
>
>
> I hate to ask but, is there something similar in Windows??
>

All operating systems with a TCP/IP stack have some means to support
the loopback IP address of 127.0.0.1 but they don't necessarily implement
it the same way as in Linux. But in no case should it involve or require a
physical NIC. That would be a bug.

Terry



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