The Cisco WSA supports two main authentication protocols: LDAP and NTLM. LDAP is a protocol for accessing and managing directory information over a network. NTLM is a Windows proprietary protocol that uses a challenge-response mechanism for authentication. The Cisco WSA can use both LDAP and NTLM to authenticate users and apply policies based on their identity. The Cisco WSA does not support WCCP, TLS, or SSL as authentication protocols, although it can use them for other purposes, such as traffic redirection or encryption. References:
* User Guide for AsyncOS 11.0 for Cisco Web Security Appliances, Chapter: Acquire End-User Credentials
* Cisco Web Security Appliance Best Practices Guidelines, Section: Active authentication
* Cisco WSA Authentication, Blog post by Kareem CCIE
* Authentication and Authorization, PDF document by Cisco