[strongSwan] Decryption of ESP packets with Wireshark

Martin Willi martin at strongswan.org
Tue Aug 10 13:30:53 CEST 2010

Hi Jessie,

> Is it correct to fill the two fields with CK and IK?

If you are referring to the encryption and integrity keys CK/IK from
EAP-AKA authentication, definitely not.

> If not, what should I fill out to get ESP packets decrypted?

IKE uses a Diffie-Hellman exchange to derive keys used for IKE and ESP
with perfect forward secrecy. You can increase the debug level of the
IKE daemon to log the key derivation process. But it is probably simpler
to use the "ip" utility to extract the keys from the kernel. Try "ip
xfrm state".


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