Ports

Port 53

Domain Name Service (DNS) Protocol = TCP and UDP Application layer The Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.

Port 67

Dynamic Host Configuration Protocol (DHCP) - Server Protocol = UDP Application layer DHCP (Dynamic Host Configuration Protocol) is a network management protocol used to dynamically assign an Internet Protocol (IP) address to any device, or node, on a network so they can communicate using IP. DHCP automates and centrally manages these configurations rather than requiring network administrators to manually assign IP addresses to all network devices. DHCP can be implemented on small local networks, as well as large enterprise networks.

Port 68

Dynamic Host Configuration Protocol - Client Protocol = UDP Application layer Clients configured with DHCP broadcast a request to the DHCP server and request network configuration information for the local network to which they're attached. A client typically broadcasts a query for this information immediately after booting up. The DHCP server responds to the client request by providing IP configuration information previously specified by a network administrator.

Port 80

Hypertext Transfer Protocol (HTTP) Protocol = TCP Application layer he Hypertext Transfer Protocol (HTTP) is the foundation of the World Wide Web, and is used to load web pages using hypertext links. HTTP is an application layer protocol designed to transfer information between networked devices and runs on top of other layers of the network protocol stack. A typical flow over HTTP involves a client machine making a request to a server, which then sends a response message.

Port 443

Hypertext Transfer Protocol Secure (HTTPS) Protocol = TCP Application layer Hypertext transfer protocol secure (HTTPS) is the secure version of HTTP, which is the primary protocol used to send data between a web browser and a website. HTTPS is encrypted in order to increase security of data transfer. This is particularly important when users transmit sensitive data, such as by logging into a bank account, email service, or health insurance provider.

Port 143

Internet Message Access Protocol (IMAP) Protocol = TCP Application layer IMAP was designed with the goal of permitting complete management of an email box by multiple email clients, therefore clients generally leave messages on the server until the user explicitly deletes them. An IMAP server typically listens on port number 143. IMAP over SSL/TLS (IMAPS) is assigned the port number 993 Internet Message Access Protocol (IMAP) is a protocol for accessing email or bulletin board messages from a (possibly shared) mail server or service. IMAP allows a client e-mail program to access remote message stores as if they were local. Email stored on an IMAP server can be manipulated from a workstation at the office, a desktop computer at home or a notebook computer while traveling, without requiring the transfer of messages or files back and forth between these computers.

Port 110

Post Office Protocol version 3 (POP3) Protocol = TCP Application layer The Post Office Protocol provides access via an Internet Protocol (IP) network for a user client application to a mailbox (maildrop) maintained on a mail server. The protocol supports download and delete operations for messages. POP3 clients connect, retrieve all messages, store them on the client computer, and finally delete them from the server. POP version 3 (POP3) is the version in common use

Port 20

Protocol = TCP File Transfer Protocol (FTP) Data Application Layer is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client-server model architecture using separate control and data connections between the client and the server. FTP users may authenticate themselves with a clear-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it

Port 21

Protocol = TCP File Transfer Protocol (FTP) - Control Application layer After the correct FTP username and password are entered through FTP client software, the FTP server software opens port 21 by default. This is sometimes called the command or control port by default. Then the client makes another connection to the server over port 20 for file transfers to take place.

Port 22

Secure Shell (SSH) Protocol = TCP Application layer Secure Shell ( SSH ) is a network protocol for accessing network services and systems over a secure connection, it does this by providing a secure channel over an unsecured network such as the internet in a client-server relationship. The most common application of this protocol would be for a user at their computer to use an SSH Client to access a SSH Server on a remote system, such a Unix/Linux based server, or a networking device such as a Cisco router SSH operates as a layered protocol suite comprising three principal hierarchical components: the transport layer provides server authentication, confidentiality, and integrity; the user authentication protocol validates the user to the server; and the connection protocol multiplexes the encrypted tunnel into multiple logical communication channels

Port 25

Simple Mail Transfer Protocol (SMTP) Protocol = TCP Application layer Simple Mail Transfer Protocol (SMTP) is a TCP/IP protocol used in sending and receiving e-mail. It is typically used with POP3 or Internet Message Access Protocol to save messages in a server mailbox and download them periodically from the server for the user.

Port 161

Simple Network Management Protocol (SNMP) Protocol = UDP Application layer In typical uses of SNMP, one or more administrative computers called managers have the task of monitoring or managing a group of hosts or devices on a computer network. Each managed system executes a software component called an agent which reports information via SNMP to the manager. SNMP is widely used in network management for network monitoring. SNMP exposes management data in the form of variables on the managed systems organized in a management information base (MIB) which describe the system status and configuration. These variables can then be remotely queried (and, in some circumstances, manipulated) by managing applications. Three significant versions of SNMP have been developed and deployed. SNMPv1 is the original version of the protocol. More recent versions, SNMPv2c and SNMPv3, feature improvements in performance, flexibility and security.

Port 23

Telnet Protocol = TCP/IP Application layer Telnet (also known as Terminal Network) is a networking protocol used to provide delivery of text between two network attached terminals or computers, typically this is for a client machine to interface with the Command Line Interface (CLI) of another machine, a piece of equipment or a server. The interface was commonly used in networking equipment (Cisco, Juniper etc.) such as routers and switches for an administrative command line interface, however more recently protocols such as SSH are becoming more popular.

Port 69

Trivial File Transfer Protocol (TFTP) Protocol = UDP Application layer Trivial File Transfer Protocol (TFTP) is a simple lockstep File Transfer Protocol which allows a client to get a file from or put a file onto a remote host. One of its primary uses is in the early stages of nodes booting from a local area network. TFTP has been used for this application because it is very simple to implement.