Messages in this thread |  | | Subject | Problem: RFC1166 addressing | From | tomc@teamics ... | Date | Mon, 16 Sep 2002 11:50:36 -0500 |
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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 eth0:1 127.1.2.3 [ running kernel 2.2.14 ]
Machine 2: ifconfig eth0:1 127.1.2.4 [ running kernel 2.4.19 ]
Machine 2: ping 127.1.2.3
Packets move between the hosts. Also seems to work on Macintosh.
tc
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