502
Modbus
Critical RiskTCP — Other
Port Overview
Port Number
502
Service Name
Modbus
Transport Protocol
TCP
Category
Other
Security Risk
Critical
Port Range
Well-Known (0-1023)
What is Port 502?
Port 502 is assigned to Modbus, widely used in industrial control systems (ICS), SCADA systems, and PLCs. No built-in authentication. Internet exposure is extremely dangerous.
TCP
Other
Commonly Used
Security Considerations
Port 502 (Modbus) is classified as critical risk. This port should not be exposed to the public internet. The service transmits data without encryption, making it vulnerable to eavesdropping, credential theft, and man-in-the-middle attacks.
Recommendation: Block this port at the firewall. Use encrypted alternatives (SSH, SFTP, HTTPS) instead.