Re: IDS, IPS and encrypted traffic

[Alexander Klimov <alserkli () inbox ru>]

On Thu, 2 Dec 2004, Daniel Hamburg wrote:
> Does anybody know some products or papers which deal with the problem of
> analyzing encrypted traffic?

It depends on encrypted by what protocol, e.g., for IPSec if you know current
secret key you can use tcpdump:

    -E     Use  spi@ipaddr  algo:secret  for  decrypting  IPsec  ESP  packets
           that  are addressed to addr and contain Security Parameter Index
           value spi.

In other situations it is more difficult to arrange (MitM) or even impossible so
it is better to avoid encryption where it is not needed. For example, if you
want to make IDS which checks SSL-protected input to your web server you should
consider inserting the IDS between SSL-processor (server-side proxy, e.g.,
stunnel) and actual http engine.

-- 
Regards,
ASK

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