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Port 1521 Details

known port assignments and vulnerabilities
threat/application/port search:
Port(s) Protocol Service Details Source
1521 tcp oracle Oracle database default listener. Oracle Database Management uses the following ports:
1521 TCP - Oracle SQL Net Listener and Data Guard
1832 TCP - Oracle Enterprise Management Agent HTTP (range 1830-1849)
49896 TCP - Oracle Clusterware (CRS daemon)

Transparent Network Substrate (TNS) Listener in Oracle 9i allows remote attackers to cause a denial of service (CPU consumption) via a single malformed TCP packet to port 1521.
References: [CVE-2002-0509], [BID-4391]

Port is also IANA registered for nCube License Manager
1521 tcp nCube License Manager (official) Wikipedia
1521 tcp Oracle database default listener, in future releases (officialport 2483) Wikipedia
1521 tcp oracle Oracle 8 SQL (default) SANS
1521 tcp oracle Oracle Database Nmap
1521 udp ncube-lm nCube License Manager Nmap
1521 tcp oracle-tns TNS Listener Neophasis
1521 tcp,udp threat Oracle SQL defaults to listening at this port (SQL*Net v2.x) Bekkoame
1521 tcp,udp ncube-lm nCube License Manager IANA
9 records found
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Related ports: 1159  1526  1527  1830  1831  1832  2621  3872  7777  7778  49896  

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External Resources
SANS Internet Storm Center: port 1521

Port numbers in computer networking represent communication endpoints. Ports are unsigned 16-bit integers (0-65535) that identify a specific process, or network service. IANA is responsible for internet protocol resources, including the registration of commonly used port numbers for well-known internet services.
Well Known Ports: 0 through 1023.
Registered Ports: 1024 through 49151.
Dynamic/Private : 49152 through 65535.

TCP ports use the Transmission Control Protocol, the most commonly used protocol on the Internet and any TCP/IP network. TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and that packets will be delivered in the same order in which they were sent. Guaranteed communication/delivery is the key difference between TCP and UDP.

UDP ports use the Datagram Protocol. Like TCP, UDP is used in combination with IP (the Internet Protocol) and facilitates the transmission of datagrams from one computer to applications on another computer, but unlike TCP, UDP is connectionless and does not guarantee reliable communication; it's up to the application that received the message to process any errors and verify correct delivery. UDP is often used with time-sensitive applications, such as audio/video streaming and realtime gaming, where dropping some packets is preferable to waiting for delayed data.

When troubleshooting unknown open ports, it is useful to find exactly what services/processes are listening to them. This can be accomplished in both Windows command prompt and Linux variants using the "netstat -aon" command. We also recommend runnig multiple anti-virus/anti-malware scans to rule out the possibility of active malicious software. For more detailed and personalized help please use our forums.

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