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RE: Blackhole Routes

  • From: Matt Ryan
  • Date: Fri Oct 01 05:00:55 2004

Something like http://www.cisco.com/en/US/products/ps5888/index.html?


Matt.

-----Original Message-----
From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of
Bill Stewart
Sent: 01 October 2004 08:23
To: Eric Germann; nanog@merit.edu
Subject: Re: Blackhole Routes



On Thu, 30 Sep 2004 10:35:36 -0400, Eric Germann <ekgermann@cctec.com>
wrote:
> What I would to see (and have never researched in depth) is a way to apply
> the blackhole routes on a community to port basis (i.e. we set up a
specific
> BGP community to filter mail, and that community goes to a route map that
> kills only port 25, another community applies to a map that kills port 80,

A not particularly scalable method of doing that, which should be ok
for small data flows,
is to set up routers port25killer.example.net, a port80killer.example.net,
etc.,
with ACLs that block those ports regardless of  address, use BGP or
OSPF to advertise
whichever IP address spaces should be routed there, and set up those
machines in
whatever sort of firewalling location makes sense.  It's more of an
enterprise solution
than an ISP solution, but if you're a small ISP or dealing with a
relatively specific
set of problem sites you could probably do it.  You may need to burn some
CPE on
GRE tunnels, depending on your topology, but if you're trying to solve
a limited problem
like letting your users access Korean web sites while blocking Korean
email, it may work.

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