Silverfort Authentication Firewall is an identity-based access control solution that enforces deny and segmentation policies at the authentication protocol level. The product connects directly to identity infrastructure to monitor and control authentication requests across all environments without requiring agents, proxies, or application modifications. The solution provides real-time blocking of suspicious authentication attempts based on risk, behavior, and context. It monitors authentication protocols including NTLM, Kerberos, and LDAP to detect and prevent unauthorized access. The platform enforces identity-based segmentation by restricting each identity to only authorized systems, preventing lateral movement even in flat or unmanaged networks. The product extends access policies to AD-managed resources including legacy systems, infrastructure, and applications. It enables security teams to dynamically restrict, isolate, or cut off access during active incidents through one-click deny policies. The solution includes a "freeze mode" capability for containing ransomware and lateral movement. Organizations can enforce least-privilege policies across user groups and systems through granular access controls. The platform integrates with existing IAM infrastructure for deployment without architectural changes or workflow disruption. It provides centralized policy enforcement across hybrid and multi-environment deployments.