BLS FastAccess internal tech needed


- ferg


not exactly... though most likely 2827 would have helped. Our abuse folks
called it 'fantasy mail' ... Spammer signs up for 'fast' link with
someone, uses a farm of juno dial (or netzero or... you get the point)
accounts to make a large number of machines dial out and start sending
email as the dial-up IP out the 'fast' link.

This was painful for a while, radius applied filters fix it now.



The problem is that an ISP can do all the source filtering it wants,
but if it only blocks SYNs to port 25 all it takes is one unfiltered
dial-up to spoof that ISP's addresses.

    --Steven M. Bellovin,

On the subject of filtering and IP spoofing...

In the past year, our spoofer project has collected nearly 1200 unique
reports from across the Internet and we have an interesting, if not
wholly representative, dataset. The latest version of our spoofer
tester includes a number of new features that may be interesting to
the community.

One particular new feature is the ability to determine where along a
tested path filtering is employed with what we're calling a "reverse
traceroute" mechanism [1]. Knowing the "filtering depth" is of
particular interest to us since there is an operational tension
between the specificity of router-level filters and the ability to
properly maintain them. We also test fun stuff such as how far into
the adjacent neighbor address space the client can spoof, filtering
inconsistencies, etc.

We'd appreciate any runs of the spoofer tester to help us gather
additional data. The client, details of the reverse traceroute as
well as our "State of IP spoofing" summary results are all the web



[1] The idea for the reverse traceroute arose from a fruitful
    discussion with John Curran.