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Port 1521: Oracle Database Listener

Port 1521 is the default port for the Oracle TNS (Transparent Network Substrate) database listener.

Protocol
TCP
Category
Databases
Common Services
Oracle Database 11g/12c/19c/21c

What is Port 1521 and How Does It Work?

Port 1521 is the default port for the Oracle TNS (Transparent Network Substrate) database listener.

Security Vulnerabilities & Attack Vectors on Port 1521

Protect Oracle listener against TNS poisoning attacks by isolating it behind internal networks.

Auditing & Scanning Port 1521 with Nmap

Run the following command to check if Port 1521 is reachable and determine service fingerprints:

nmap -p 1521 --script oracle-tns-version

Frequently Asked Questions

How do I check if Port 1521 is open?
Use cyber-tool.org diagnostic tools or run 'nc -zv 1521' in your terminal to verify open socket connections.
Is it safe to leave Port 1521 open to the internet?
Exposing Port 1521 (Oracle Database Listener) publicly introduces potential exposure. Protect it with IP whitelisting, firewalls, and encryption.