Problem: RFC1166 addressing

Date: Mon Sep 16 2002 - 11:50:36 EST

RFC 1166 states that:

 The class A network number 127 is assigned the "loopback"
         function, that is, a datagram sent by a higher level protocol
         to a network 127 address should loop back inside the host. No
         datagram "sent" to a network 127 address should ever appear on
         any network anywhere.

 Linux does not enforce this. I have uncovered some users using this
function to attempt to circumvent the firewall. I am able to "create" 127
network traffic as follows:

Machine 1: ifconfig eth0:1 [ running kernel 2.2.14 ]

Machine 2: ifconfig eth0:1 [ running kernel 2.4.19 ]

Machine 2: ping

Packets move between the hosts. Also seems to work on Macintosh.


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This archive was generated by hypermail 2b29 : Mon Sep 23 2002 - 22:00:17 EST