AS Leakage (filter)

Robbie Harrell robbie.harrell at
Thu Apr 5 16:10:59 UTC 2001

Is there a published list of best practice filters out there?  

-----Original Message-----
From: owner-nanog at [mailto:owner-nanog at]On Behalf Of
Christian Nielsen
Sent: Wednesday, April 04, 2001 9:42 PM
To: John Fraizer
Cc: nanog at
Subject: Re: AS Leakage (filter)

On Thu, 5 Apr 2001, John Fraizer wrote:

> How many ways can I say "I didn't realize that Christian was speaking
> about Exodus?

I try to speak about networks in general. I hope that many people on the
list understand peering and filtering.

For example. If I peer with any provider, from Sprint to the provider
sending me 1 route I will filter _701_ from all of them. I will also
filter _1239_ from _701_ and all other peers. Please be aware, that I used
the term PEER and not Transit provider.

I would filter the RFC1918 from peers and transit providers. I would
filter IANA-RESERVED. I would filter my own IP space (no reason to see
someone else deagg towards me)

People have emailed me privately about filtering and I have given some
examples of filtering.

At the end of Feb, Steve Meuse and I talked about filtering at the LINX
meeting. If people would have followed some of the information given, they
might not have had a problem when an internet provider leaked the linx IP

access-list 1 deny
access-list 1 deny

Here is the URL if anyone would like to look at some of the filtering
Exodus does


> I _DID_NOT_KNOW_ that Christian worked for Exodus.
> I _DID_NOT_KNOW_ that Christian worked for Exodus.
> I _DID_NOT_KNOW_ that Christian worked for Exodus.

btw, i still work for Exodus...

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