Security Incidents mailing list archives

Re: Private networks and home.{net|com}


From: peak () ARGO TROJA MFF CUNI CZ (Pavel Kankovsky)
Date: Thu, 10 Feb 2000 12:35:50 +0100


On Wed, 9 Feb 2000, Rasmus Andersson wrote:

It's perfectly legal (and in many ways good) to use those addresses on
link networks, and filtering out ALL traffic from such addresses is a
therefore a Bad Idea(tm). In particular, you MUST let ICMP Unreachable -
Fragmentation Needed through to not damage path-MTU discovery. IMHO you
should let any ICMP Unreachables through as well as Time Exceeded.

I might have a very good reason not to allow any RFC-1918-address
originated datagrams from outside: I might be using these addresses
myself in my internal network. Why should I allow anyone to spoof
internal traffic of any kind?

IMHO, it is a Bad Idea(tm) to allow a PRIVATE address to appear in a
PUBLIC network! And people who do it are messing things up themselves.

--Pavel Kankovsky aka Peak  [ Boycott Microsoft--http://www.vcnet.com/bms ]
"Resistance is futile. Open your source code and prepare for assimilation."


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