Re: TCP RST attack

On Tue, Apr 20, 2004 at 01:45:20PM -0700, Matthew Dillon wrote:
>     On the other hand, BGP can be trivially protected.  You don't need
>     ingress or egress filtering at all (by which I mean IP block filtering),
>     you simply disable the routing of any packet to or from port 179.
>     99.9% of all BGP links are direct connections (meaning that they
>     terminate at a router rather then pass through one).  No packet to
>     or from port 179 has any business being routed from one network to
>     another in virtually all BGP link setups so the fix is utterly trivial.

most multi-router, multi-link setups use peering with a multihop address
of some other router (or route server) to provide equal cost balancing.
RFC3682 describes something along the same vein of what you suggest, but
handles non-directly connected cases (multihop, tunnels, etc) better.

vendor J lets you dynamically build your firewall rules such that you
can actually just create a term "allow from all bgp neighbors in the
config AND port 179 AND protocol tcp". vendor C would do well to provide
something similar. those running freebsd bgp daemons should consider
building something similar that feeds ${freebsd_packet_filter} from a
${freebsd_routing_daemon} configuration file.

-- 
- bill fumerola / [e-mail] / [e-mail]


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