[AusNOG] Bogon Update

Martin - StudioCoast martin.sinclair at studiocoast.com.au
Thu Aug 25 19:02:57 EST 2011

Below is a basically summary of the steps involved, rest assured its not 
for the faint hearted and I lost a couple of weeks working on it!

Inspired by http://www.anchor.com.au/blog/2009/05/testing-your-connectivity/

1. Retrieve a copy of the full routing table (I used 

2. Wrote a vb.net program to extract the first subnet for each ASN.

For example our subnet appears as:
*             0      0      0 8492 3356 
24130 24473 24473 i

The ASN we use is 24473

3. Once I had the subnet list (approximately 38000 entries) I wrote 
another program to ping the first 50 ip addresses of every subnet on my 
ADSL connection trying to find a pingable address.
Using multithreading and a 1mbit upload, this took around a couple of hours.

4. The final list of 28000 entries is on our website 
http://www.studiocoast.com.au/downloads/asn-reach-test.txt (as always, 
use at own risk)
The test was completed last weekend from an Internode ADSL connection, 
many of the IP addresses may no longer be reachable.

5. The final list was then pinged simultanously from both 
and another debogoned range on the same network.

6. The result was about 400 ASNs that could not be accessed. I then used 
the various IP whois servers to retrieve the technical email contacts 
and send them an email requesting the prefix be de-bogoned.
Only around 250 ASNs had contact emails that I could find.
In the email I referenced http://www.ris.ripe.net/cgi-bin/debogon.cgi, 
Cymru and the IETF draft.

7. Around 120 ASNs responded and fixed their filters.


Martin Sinclair

On 25/08/2011 12:15 PM, Martin - StudioCoast wrote:
> Hi,
> Just thought I would let everyone know that the bogon filtering issues 
> on the block are now resolved amongst australian isps.
> As far as I can tell, visibility is 100% in Australia now that Three 
> have removed their filter.
> I have also completed an ASN scan of the greater internet (all 38000 
> of them!) and identified 300 ASNs that may be blocking the prefix.
> Each ASN owner was contacted and so far 130 or so have removed the filter.
> If anbody would like some further information on how the tests were 
> conducted let me know.
> Regards,
> Martin Sinclair
> StudioCoast
> _______________________________________________
> AusNOG mailing list
> AusNOG at lists.ausnog.net
> http://lists.ausnog.net/mailman/listinfo/ausnog
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