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Re: Lazy Engineers and Viable Excuses
From: Iljitsch van Beijnum <iljitsch () muada com>
Date: Tue, 26 Aug 2003 17:39:28 +0200

On dinsdag, aug 26, 2003, at 17:03 Europe/Amsterdam, Leo Bicknell wrote:

Now, the customer, over their two T1 transit circuits does the

as-path access-list 1 deny .*

neighbor verio filter-list 1 in

ip route sprint

Should the customer have to register a route with Sprint to make
this work?  How does UUNet, who only received a route from Verio,
know incoming packets from Sprint aren't spoofed?

You're not saying anything about outgoing route advertisements here so these questions are unanswerable.

My position is that if you want to use certain source addresses, you should announce and register the route that goes with those addresses. Expecting the whole world to forego uRPF just because that makes your life easier isn't realistic.

However, maybe we're spending too much effort on the whole source address spoofing issue, as stopping this doesn't really solve the core problem, which is how to shut up undesired incoming traffic.

Looking up the unspoofed source address in a registry and then email or phone the listed contact isn't exactly a sure fire way to do this.



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