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TCP
Vulnerable
1521 Oracle Database
Oracle listeners use port 1521 for client connectivity, service discovery, and administration handshakes.
Security Context
Port 1521 is high-risk when broadly exposed. Treat it as an attack-surface decision, not just a connectivity setting, and confirm whether the listener truly needs to be reachable.
- !Directly exposed database listeners expand attack surface substantially.
Nmap Check
Use a version probe first so you confirm whether the expected service is really what is listening on this port.
nmap -sV -p 1521 <host>Firewall Commands
UFW
sudo ufw allow 1521/tcpiptables
sudo iptables -A INPUT -p tcp --dport 1521 -j ACCEPT