[strongSwan] Is a trusted man in the middle possible with ipsec ike v2 tunnel mode?

Martin Willi martin at strongswan.org
Thu Apr 24 10:37:11 CEST 2014


> question is the keys for the ESP/AH ...  are they static? if so, where
> are they in the Security gateway.. if they are dynamic(change from time
> to time), where are they in the security gateway?  and the dynamic ones,
> how are they changing?? is that a function of the IPsec IKEv2 stuff?

The CHILD_SA encryption and integrity keys are derived from the
Diffie-Hellman exchange done in IKE, mixed with some additional data.
They get periodically refreshed using rekeying.

If you set the loglevel of "chd" to 4 to get them printed to your log,
see [1]. You may even automate the process of extracting keys with a
plugin if you register a listener on the bus and use the child_keys()
hook [2] to intercept the key material for key derivation. You'd have to
do that manually to get the final encryption keys, but should be doable

Once you extracted these keys, you may forward them to your MITM box to
snoop traffic, for example with Wireshark.



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