Hostname funniness

[Dmitriy Kropivnitskiy]

>From the RFC 3300 

   127.0.0.0/8 - 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 127.0.0.1/32 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 127.0.0.0 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 255.0.0.0 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 192.168.0.1 and netmask 255.255.255.0 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.
> 
>