Here are some commonly used port numbers:
- 20, 21: FTP (File Transfer Protocol)
- 22: SSH (Secure Shell)
- 23: Telnet
- 25: SMTP (Simple Mail Transfer Protocol)
- 53: DNS (Domain Name System)
- 80: HTTP (Hypertext Transfer Protocol)
- 110: POP3 (Post Office Protocol version 3)
- 143: IMAP (Internet Message Access Protocol)
- 443: HTTPS (HTTP Secure)
- 3306: MySQL
- 3389: Remote Desktop Protocol (RDP)
- 8080: Alternate HTTP port (commonly used for web proxies and caching)
Note that this is just a small selection of the many port numbers in use.
20, 21: FTP (File Transfer Protocol):
FTP (File Transfer Protocol) is a standard network protocol used to transfer files between a client and a server over a TCP-based network such as the Internet. FTP uses two channels, one for commands and one for data transfer. It typically operates in a client-server architecture, where a client program establishes a connection to an FTP server to send and receive files.
To use FTP, a user needs to log in to an FTP server using their username and password, and then navigate through the server's directory structure to locate the files they wish to transfer. FTP supports various file transfer modes, including ASCII and binary, to ensure that files are transferred correctly and without corruption. FTP also includes commands for managing files on the server, such as renaming, deleting, and creating directories.
FTP has been widely used for many years as a way to transfer files, but it is gradually being replaced by more secure file transfer protocols such as SFTP (Secure File Transfer Protocol) and FTPS (FTP over SSL/TLS).
22: SSH (Secure Shell)
SSH (Secure Shell) is a secure network protocol used to establish a secure and encrypted connection between two devices over an unsecured network. SSH is commonly used for remote login and to securely transfer files.
SSH provides strong encryption and authentication, protecting against eavesdropping and tampering by attackers. It uses public-key cryptography to authenticate the client and server, and to negotiate a symmetric encryption algorithm to be used for the session. This provides a secure channel over which users can securely log in to a remote server or transfer files.
SSH typically operates on TCP port 22, but it can be configured to use a different port if necessary. SSH is commonly used in Unix and Linux systems, but there are also SSH clients and servers available for other operating systems, including Windows and macOS.
SSH is a powerful and flexible tool that is widely used in the IT industry for various purposes, including remote administration, tunneling, and transferring files securely.
23: Telnet:
Telnet is a network protocol used for remote access to a computer or server. It provides a command-line interface, allowing users to log in to a remote system and execute commands. Unlike SSH, Telnet does not provide encryption, making it less secure for transmitting sensitive data over the network. Due to its security vulnerabilities, Telnet is generally not recommended for use in modern networks, and SSH is typically used as a more secure alternative.
SMTP (Simple Mail Transfer Protocol):
SMTP (Simple Mail Transfer Protocol) is a network protocol used for sending and receiving email messages over the internet. It is responsible for the transfer of email messages from a mail client or server to a recipient's mail server. SMTP uses a store-and-forward mechanism to route email messages between mail servers, and it also provides error reporting and message queue management. SMTP is a key component of the email infrastructure and is widely used by email clients and servers for sending and receiving emails.
53: DNS (Domain Name System):
DNS (Domain Name System) is a hierarchical system that translates human-readable domain names, such as www.example.com, into machine-readable IP addresses, such as 192.0.2.1, which are used by computers to identify and communicate with each other on the internet. DNS is critical to the functioning of the internet, as it allows users to access websites and other online resources by their familiar names, rather than having to remember numerical IP addresses. DNS operates through a distributed network of servers that collectively store and maintain a database of domain names and their associated IP addresses, allowing queries to be quickly and efficiently resolved.
80: HTTP (Hypertext Transfer Protocol):
HTTP (Hypertext Transfer Protocol) is an application-layer protocol used for transmitting data over the internet. It is the foundation of data communication on the World Wide Web and enables the transfer of text, images, videos, and other multimedia files between web servers and clients. HTTP uses a client-server model, where the client sends a request to the server, and the server responds with the requested data. The protocol uses a request-response structure, where requests from clients contain methods such as GET, POST, and PUT, and responses from servers contain status codes such as 200 OK and 404 Not Found.
110: POP3 (Post Office Protocol version 3):
POP3 (Post Office Protocol version 3) is a standard email protocol used for retrieving email messages from a mail server. It is one of the most commonly used email retrieval protocols, along with IMAP and Exchange ActiveSync. With POP3, email clients connect to the mail server and download email messages to the local device. After downloading, the messages are usually deleted from the server, although some email clients can be configured to keep a copy of the messages on the server. POP3 uses TCP port 110 for plain text, and port 995 for SSL-encrypted connections. POP3 is a simple and widely supported protocol, but it lacks some of the advanced features offered by IMAP, such as server-side searching and mailbox synchronization across multiple devices.
143: IMAP (Internet Message Access Protocol):
IMAP (Internet Message Access Protocol) is an email protocol used for accessing and managing email messages on a remote mail server. Unlike POP3, which downloads email messages to a local device and then typically deletes them from the server, IMAP allows email clients to view and manipulate email messages directly on the server. This means that email messages are accessible from multiple devices, and changes made on one device are reflected on all devices that access the same email account. IMAP uses TCP port 143 for plain text, and port 993 for SSL-encrypted connections. IMAP offers advanced features such as server-side searching, mailbox synchronization across multiple devices, and support for multiple folders or labels. However, because IMAP requires more server resources than POP3, some email providers may charge extra for IMAP access or impose limitations on mailbox size.
443: HTTPS (HTTP Secure):
HTTPS (HTTP Secure) is a protocol for secure communication over the internet, commonly used to protect sensitive data such as login credentials, financial transactions, and personal information. HTTPS is essentially the same as HTTP (Hypertext Transfer Protocol), but with an added layer of security provided by SSL/TLS encryption. SSL/TLS (Secure Sockets Layer/Transport Layer Security) is a protocol that establishes an encrypted connection between a web server and a client, ensuring that data is protected from interception or tampering by unauthorized parties. HTTPS uses TCP port 443, and is often indicated in web browser addresses by a padlock icon and/or the "https://" prefix. HTTPS is increasingly important for website owners and online businesses, as it can help to build trust with users and improve search engine rankings.
3306: MySQL:
MySQL is a popular open-source relational database management system. It is widely used for creating and managing databases for various applications and websites. MySQL supports a wide range of programming languages, including PHP, Python, Java, and C++, and can be used on various operating systems, including Windows, Linux, and macOS. MySQL uses Structured Query Language (SQL) to manage and manipulate data. Some of its features include support for multiple storage engines, scalability, high availability, security, and compatibility with various web technologies. MySQL is used by many large organizations, including Facebook, Google, and Amazon, as well as by many small and medium-sized businesses and individual developers. It is free to download and use, with paid support and commercial licensing options available from the vendor.
3389: Remote Desktop Protocol (RDP):
Remote Desktop Protocol (RDP) is a proprietary protocol developed by Microsoft that allows a user to connect to and control a remote computer or virtual machine over a network connection. With RDP, a user can access a remote computer as if they were sitting in front of it, using their own keyboard, mouse, and display. RDP is commonly used for remote administration, remote access, and telecommuting, as well as for virtualization and cloud computing environments. RDP uses TCP port 3389, and can be used on various operating systems, including Windows, Linux, and macOS. RDP sessions can be secured using various authentication and encryption methods, and can be customized with various settings and policies to meet specific security and usability requirements.
8080: Alternate HTTP port (commonly used for web proxies and caching):
Port 8080 is an alternate HTTP (Hypertext Transfer Protocol) port used to bypass network restrictions that may block the standard HTTP port (port 80). It is commonly used for testing and debugging web applications or for running web servers on non-standard ports. When a web server is configured to listen on port 8080, clients can access the web server by specifying the port number in the URL (e.g., http://example.com:8080). Port 8080 is not a reserved port and can be used for any purpose, although it is commonly associated with HTTP proxy servers and various web development tools. In some cases, network administrators may block access to port 8080 in the same way they would block access to port 80, so it may not always be a reliable alternative.
- #Network communication
- #Transport layer
- #Socket
- #Endpoint
- #TCP/IP
- #Internet Assigned Numbers Authority (IANA)
- #Well-known ports
- #Registered ports
- #Dynamic ports
- #Port forwarding
