Access to the Internic Blocked

Vadim Antonov avg at
Fri Aug 23 05:22:03 UTC 1996

Curtis Villamizar wrote:

> Not at all.  LSRR is a nice tool to mount practically untraceable
> flooding attack (hint -- just forge source address and spread
> intermediate points evenly across the network).  Shutting you
> down may be exactly what the attacker wants.

>Oh come on.  Like they're not going to get caught stuffing an entire
>T1 with LSRR packets.  Face it.  You're grabbing at straws.

Ugh.  To kill multiple DS-3s you don't even need a full T-1
(you need one LS address for every loop), and you can kill multiple
DS-3s and an IXP to boot, with the single stream of bogons routed
in a loop with many hops.  And there's a lot of big name Us with
DS-3 connectivity and no security whatsoever.

Now, throw in randomized first hop and forged source address,
and i'll wish you good luck catching the perpetrator.  A careful
attacker would also randomize destinations and make it to look like
regular TCP traffic.

(And did anybody think of IP stacks which reverse the source
routes, just to make things funnier).

>Besides the fact that with your suggestion of traceroute using ICMP
>echo requests they'd just send a T1s worth of ICMP echo requests with
>LSRR and accomplish the same thing.

Ok, with only one intermediate point allowed.  _That_ should
take care of all diagnostic needs.

>LSRR is just too useful for diagnosing network problems to shut down
>on a backbone.

I sometimes wonder if the threat of hackers is exaggregated.
They certainly missed a nice opportunity to crash the Internet
with TCP resets on iBGPs.  Now nobody cares about the creative
potential of LSRR-anonymized denial of service attacks.  They
must be stupid or something.

Should i write a backbone-crasher and post it to USENET just to
make a point about LSRRs?  Note that a provider which won't
shut LSRR will be the threat to others...


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