Port 902 (VMware)

TCP port 902 is primarily associated with VMware products, specifically the VMware Authentication Daemon (vmware-authd). This daemon is responsible for authenticating users and managing sessions for various VMware applications, including vSphere Client, vCenter Server, and ESXi hosts. At a technical level, when a user attempts to connect to a VMware environment, the application communicates with vmware-authd on port 902 to verify the user's credentials and establish a secure session. The authentication process typically involves a challenge-response mechanism to prevent unauthorized access. The protocol used is a proprietary VMware protocol, often encapsulated within SSL/TLS for added security during authentication and subsequent communication. The vmware-authd service then grants the connecting client the necessary permissions to interact with the ESXi host or vCenter server.

The history of port 902's association with VMware dates back to the early days of VMware's virtualization platform. Its purpose was to provide a dedicated and consistent port for handling authentication across different VMware products, simplifying network configuration and management. The daemon handles authentication requests, validates user credentials against configured authentication sources (e.g., local users, Active Directory), and authorizes access to virtual machines and other resources. The design of vmware-authd is intended to be modular and extensible, allowing it to support different authentication mechanisms and integrate with various identity management systems. The service is crucial for maintaining security and controlling access to virtualized environments.

## Firewall Recommendations

It is generally recommended to restrict access to port 902 to only authorized IP addresses or networks. If possible, place the vCenter Server and ESXi hosts behind a firewall and only allow connections from trusted sources. Implement strong authentication mechanisms, such as multi-factor authentication, to prevent unauthorized access. Always use SSL/TLS to encrypt communication between clients and the vmware-authd service. Regularly patch and update VMware products to address known vulnerabilities. Consider using network segmentation to isolate the VMware environment from other parts of the network. Monitor network traffic for suspicious activity, such as unusual connection patterns or brute-force attempts. If the VMware environment is not directly exposed to the internet, blocking port 902 from external access is a prudent security measure. Ensure proper access control lists (ACLs) are in place to restrict which users and systems can access the VMware environment. Regularly review and update firewall rules to reflect changes in the network environment and security policies.