Login Host Protocol

TACACS (Terminal Access Controller Access-Control System) is a protocol used to provide centralized authentication, authorization, and accounting (AAA) services for users accessing network devices. It is commonly used in enterprise environments to manage user access and ensure security. TACACS operates over TCP port 49.

What is Login Host Protocol

TACACS, or Terminal Access Controller Access-Control System, is a protocol developed to provide centralized authentication, authorization, and accounting (AAA) services for users accessing network devices. Originally developed by BBN Technologies for ARPANET, TACACS has evolved over the years, with TACACS being the most recent and widely used version. TACACS offers enhanced security features, including encryption of the entire packet body, making it more secure than its predecessors.

In enterprise environments, TACACS is commonly used to manage user access to routers, switches, and other network devices. By centralizing the AAA functions, TACACS simplifies the management of user credentials and permissions, ensuring that only authorized users can access critical network infrastructure. This centralization also allows for detailed logging and auditing of user activities, which is essential for maintaining security and compliance.

TACACS operates over TCP port 49, providing reliable and secure communication between the client and the TACACS server. The protocol's flexibility and robustness make it a preferred choice for organizations looking to implement strong access control measures. Despite the availability of other AAA protocols like RADIUS, TACACS remains popular due to its granular control over authorization and its ability to handle complex network environments.

Login Host Protocol runs on TCP and UDP port 49 and is official IANA port.

Security risk

If port 49 is open and the TACACS service is running, it could be a target for unauthorized access attempts. Attackers could exploit vulnerabilities in the TACACS implementation to gain access to network devices, potentially compromising the entire network. Ensuring that TACACS is properly configured and secured is essential to mitigate these risks.

In our UFW tutorial you can follow instructions how you can configure UFW to close port 49. Use StackChanges to monitor if the Login Host Protocol port is closed and stays closed. StackChanges will send an alert if port 49 is open again.