This article describes the Perfect Forward Secrecy (PFS) support for SSLVPN.
In cryptography, perfect forward secrecy (PFS), is a property of secure communication protocols in which compromise of long-term keys does not compromise past session keys. Forward secrecy protects past sessions against future compromises of secret keys or passwords.
SSLVPN does not use any DH (Diffie-Hellman) or ECDHE (Elliptic-Curve Variant) system hence the Perfect Forward Secrecy (PFS) is not an available option for UTM SSLVPN.