strongSwan is a complete IPsec and IKEv1 implementation for Linux 2.4 and 2.6 kernels. It also fully supports the new IKEv2 protocol with Linux 2.6 kernels. It interoperates in both IKEv1 and IKEv2 mode with most other IPsec-based VPN products. The focus of the strongSwan project is on strong authentication mechanisms using X.509 public key certificates and optional secure storage of private keys on smartcards through a standardized PKCS#11 interface. A unique feature is the use of X.509 attribute certificatesto implement advanced access control schemes based on group memberships.License: GNU General Public License (GPL)Changes:
The IKEv2 keying daemon has become modular and thus more extensible. Plugins for MySQL and SQLite allow you to store configurations and user credentials in a relational database. All cryptographic algorithms have been implemented as plugins, so that any software or hardware-accelerated crypto module can be attached during runtime.

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