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Network Port Information
| Port | Protocol | Service Name | Description |
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A Guide to Network Ports, TCP/UDP, and Firewall Security
Instantly look up any common network port to understand its purpose with our searchable Port Information Tool. This guide is an essential resource for network administrators, cybersecurity professionals, and students to identify services associated with TCP/UDP ports, understand their function, and make informed decisions when configuring firewalls and troubleshooting network connectivity.
About the Port Information Tool
The Network Port Information tool is a quick reference guide that helps you identify the services associated with common TCP and UDP port numbers. In TCP/IP networking, ports are used to differentiate between multiple applications or services running on a single device. When data arrives at a computer's IP address, the port number tells the operating system which application should receive the data. Our tool provides a live search of a comprehensive list of well-known and registered ports, so you can quickly find the protocol, service name, and description for any port number.
How to Use the Tool
Using the tool is fast and intuitive.
Using the Port Lookup
- Enter a Search Term: In the search box, you can type a port number (e.g., `3389`), a service name (e.g., `RDP` or `Remote Desktop`), or a protocol (e.g., `TCP`).
- View Live Results: The table will filter instantly as you type, showing all entries that match your search query. There is no need to press enter or click a button.
- Find Your Information: The table provides the port number, the protocol(s) it uses, its common service name, and a clear description of its function.
The Fundamentals of Network Ports
Network ports are a foundational concept in computer networking, acting as virtual doorways on a computer that allow it to sort incoming and outgoing traffic for specific services.
TCP vs. UDP: The Two Main Protocols
Ports are used by the two primary transport layer protocols:
- TCP (Transmission Control Protocol): This is a connection-oriented protocol. It establishes a reliable connection and ensures that all data arrives in the correct order without errors. It is used for applications where data integrity is paramount, like web Browse (HTTP/HTTPS), email (SMTP), and file transfers (FTP).
- UDP (User Datagram Protocol): This is a connectionless protocol. It is much faster and has less overhead than TCP, but it does not guarantee that packets will arrive or that they will be in the right order. It is used for real-time applications like video streaming, online gaming, and DNS lookups, where speed is more critical than perfect reliability.
Port Number Ranges
The 65,536 available ports are divided into three ranges by the Internet Assigned Numbers Authority (IANA):
| Port Range | Name | Description |
|---|---|---|
| 0 - 1023 | Well-Known Ports | These are reserved for common, standardized system services (e.g., HTTP on port 80, SSH on port 22). On Unix-like operating systems, root privileges are typically required to run a service on these ports. |
| 1024 - 49151 | Registered Ports | These ports are registered with IANA for specific applications (e.g., Microsoft SQL Server on 1433, MySQL on 3306). They can also be used by other applications without registration. |
| 49152 - 65535 | Dynamic / Private / Ephemeral Ports | This range is used for temporary, outbound connections. When your web browser connects to a web server on port 443, it uses a random port from this range as its source port for the session. |
Ports and Firewall Security
One of the primary functions of a firewall is to control which ports are open and accessible on a network or device. The principle of "least privilege" is a core security concept: by default, all ports should be closed, and only the specific ports required for legitimate business functions should be explicitly opened.
For example, a web server should only have ports 80 (HTTP) and 443 (HTTPS) open to the internet. All other ports should be blocked by the firewall to minimize the server's "attack surface" and prevent unauthorized access to other services.
This tool is a reference for identifying the *intended* use of a port. For security auditing, a network professional would use a port scanning tool (like Nmap) to determine which ports are *actually* open on a system, and then use that information to validate firewall rules and system configurations.
Frequently Asked Questions about Network Ports
What is a network port?
A network port is a numerical identifier from 0 to 65535 that serves as an endpoint for communication in a host's operating system. It allows a single IP address to handle multiple conversations with different services simultaneously. For example, your computer can browse a website (using port 443) while also sending an email (using port 25).
What is the difference between TCP and UDP?
TCP (Transmission Control Protocol) is a connection-oriented protocol that guarantees reliable, ordered data delivery. It's used for applications where data integrity is crucial, like web Browse (HTTP/HTTPS) and email. UDP (User Datagram Protocol) is a connectionless protocol that is faster but does not guarantee delivery. It's used for real-time applications like video streaming and online gaming where speed is more important than perfect reliability.
How do I use this port information tool?
Simply type a port number, service name, or protocol into the search box. The table will instantly filter to show you the relevant information for any matching entries.
What is port 80 used for?
Port 80 is the standard port for HTTP (Hypertext Transfer Protocol), which is the protocol used for unencrypted web traffic.
What is port 443 used for?
Port 443 is the standard port for HTTPS (HTTP Secure), which is the encrypted and secure version of HTTP used by all modern websites.
Why would a port be 'open'?
A port is 'open' on a server or device if there is an application or service actively listening for incoming connections on that port. For example, a web server must have port 443 open to accept HTTPS connections from visitors.
Is an open port a security risk?
An open port is only a security risk if the service listening on that port is vulnerable, misconfigured, or unpatched. However, a core security principle is to close all ports that are not absolutely necessary to minimize the 'attack surface' of a device.
What is a firewall?
A firewall is a network security device that monitors and filters incoming and outgoing network traffic based on a set of security rules. It acts as a barrier between a trusted internal network and an untrusted external network, like the internet. You can use our ACL Generator to create basic firewall rules.
What are 'well-known ports'?
Ports 0 through 1023 are designated as 'well-known ports' by IANA (Internet Assigned Numbers Authority). They are reserved for common, standardized services like HTTP (80), FTP (21), and SSH (22).
What is port forwarding?
Port forwarding is a technique used on a router to direct incoming traffic from the internet on a specific port to a specific device on the internal, private network. For example, you might forward port 3389 to your desktop computer's IP to allow for Remote Desktop access from outside your home.
What port does RDP use?
RDP (Remote Desktop Protocol) uses TCP port 3389 by default.
What port does SSH use?
SSH (Secure Shell) uses TCP port 22 by default for secure remote command-line access.
Can I check if a port is open on a remote computer with this tool?
No, this is a port information lookup tool, not a port scanner. It tells you what a port is *typically* used for. To check if a port is actually open on a specific server or IP address, you would need a port scanning tool.
What are registered ports?
Ports 1024 through 49151 are known as 'registered ports'. They can be registered with IANA for specific services, but are also commonly used by applications for ephemeral (temporary) connections.
What are ephemeral ports?
Ephemeral (or dynamic/private) ports, from 49152 to 65535, are used by a client's operating system as a temporary source port when initiating a connection to a server. For example, when your browser connects to a web server on port 443, it uses a random ephemeral port as its source.
Why does FTP use two ports (20 and 21)?
In its classic 'active mode', FTP uses port 21 for the command and control channel (sending commands like 'get' or 'put') and port 20 for the separate data channel where the actual file is transferred.
What is the difference between POP3 and IMAP?
Both are protocols for retrieving email. POP3 (Port 110) typically downloads emails from the server to a single device and then deletes them from the server. IMAP (Port 143) syncs emails with the server, allowing you to access the same mail from multiple devices.
What is DNS and what port does it use?
DNS (Domain Name System) translates domain names into IP addresses. It typically uses UDP port 53 for fast queries. Our DNS Lookup tool can be used to check DNS records.
What is SMB and what port does it use?
SMB (Server Message Block) is a protocol used for file sharing, printer sharing, and other network services, primarily in Windows environments. It uses TCP port 445.
Should I change default ports for services like SSH or RDP?
Changing the default port of a service is a security practice known as 'security through obscurity'. While it can reduce the number of automated attacks and scans against the default port, it is not a substitute for strong passwords, two-factor authentication, and proper firewall rules.
How many network ports are there?
There are a total of 65,536 possible port numbers for both TCP and UDP, ranging from 0 to 65535.
What is the purpose of the Syslog port?
Syslog uses UDP port 514 to allow network devices (like routers, switches, and firewalls) and servers to send event log messages to a central logging server. This is crucial for network monitoring and security analysis.
What is SNMP and what port does it use?
SNMP (Simple Network Management Protocol) is used by network administrators to monitor and manage network devices. It typically uses UDP port 161 for queries and UDP port 162 for receiving asynchronous traps (alerts).
Can two services use the same port at the same time?
On the same IP address, two services cannot use the same port and protocol combination at the same time. For example, you cannot have two web servers both listening on TCP port 80 on the same machine. However, a TCP service and a UDP service can both use the same port number.
Do I need a network professional to manage firewall ports?
For a business network, yes. Properly configuring firewall rules to open only necessary ports and block all others is a critical security task. An IT or security professional is needed to assess which ports are required for business operations and to implement the rules securely to protect the network from external threats.