Reference Guide
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HTTP Proxy
Auto-Login for Kron PAM HTTP P...
Auto-Login with Encoded Credential
The HTTP basic authentication is a simple challenge and response mechanism with which a server can request authentication information (a user ID and password) from a client. The client passes the authentication information to the server in an Authorization header. The authentication information is sent in base-64 encoding format.

To use the auto-login feature, the http.auto.login.username.matcher.template and http.auto.login.password.matcher.template must have the same value as CastleAuthorization=Basic%20$$value$$(&|$). The "username:password" content will be encoded with Base64 and the matched pattern within the request body will be replaced with the encoded content.