Hostname funniness

Dmitriy Kropivnitskiy nigde at
Thu Nov 18 15:46:38 CST 2004

>From the RFC 3300 - This block is assigned for use as the Internet host
   loopback address.  A datagram sent by a higher level protocol to an
   address anywhere within this block should loop back inside the host.
   This is ordinarily implemented using only for loopback,
   but no addresses within this block should ever appear on any network
   anywhere [RFC1700, page 5].

This means, that in order to be RFC compliant, lo interface DOES do some IP magic and answers on any address from the block. 
This is not a normal behavior for a network interface though, and no evidence for it can be seen in ifconfig output.

On Thu, 2004-11-18 at 16:36 -0500, Dmitriy Kropivnitskiy wrote:

> Netmask of doesn't mean that an interface listens on the whole
> A class, just means that only the first 8 bits of the address is the
> network number and the rest is the host number. In this case the host
> number is 1 and network number is 127. For example if your eth0
> interface has address and netmask it is not
> going to listen on the whole /24 but only on the .1 address. So, I
> suppose there is some magic in the lo interface making it answer on any
> address from 127. A class. I will go read RFCs now.

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