nanog mailing list archives

Re: identify hostname


From: Pete Kruckenberg <pete () kruckenberg com>
Date: Tue, 1 Dec 1998 12:29:15 -0700 (MST)

On Tue, 1 Dec 1998, Alex P. Rudnev wrote:

UUnet uses ascend TNT's which they claim you cant filter 
directed-broadcast on. Ive ranted at them since October 20 to get this
serious security hole closed.
If they can't turn this off on ascend access server, they anyway can 
filter out broadcast addresses in their border routers (CISCO's) 
forwarding traffic to this access servers. The result is (almost) the 
same.

Filtering broadcast addresses is pretty ugly. Consider that a single Class
C broken down into /30's can have 64 broadcast addresses. Maybe if it was
just filtering your own assigned subnets, it would be possible, but this
also applies to customer-subnetted broadcast addresses, so you'd have to
coordinate your filter with every one of your customers, every time they
change subnets. Not impossible, but pretty close.

Pete.




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