Core issue
The PIX Firewall needs to be configured to communicate with a TACACS+ or RADIUS server.
Resolution
To resolve this issue, perform these steps:
- Configure Authentication, Authorization and Accounting (AAA) on the PIX Firewall and AAA server.
- Re-enable extended authentication (Xauth).
- Retry the client VPN connection.
For more information, refer to these documents:
PIX Software Version
PIX version 5.x
PIX version 6.x
VPN Tunnel Initialization
Cannot pass phase I (Internet Security Association and Key Management Protocol [ISAKMP])