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SubjectProblem: RFC1166 addressing
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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