* **FTP - Data** (File Transfer Protocol - Data) : **TCP Port 20** - FTP Data is used to transfer data from a server or transfer data to a server (e.g., uploading a Web page file to a server).

  * **FTP - Control** (File Transfer Protocol - Control) : **TCP Port 21** - FTP Control is used to open a connection to the FTP server.

  * **SSH** (Secure Shell) : **TCP Port 22** - SSH is a network protocol that allows data to be exchanged over a secure channel between two computers.

  * **Telnet** (Telecommunication Network) : **TCP Port 23** - A terminal emulation program to remotely control Web servers.

  * **SMTP** (Simple Mail Transfer Protocol) : **TCP Port 25** - SMTP is a protocol used for sending e-mail messages between servers.

  * **DNS** (Domain Name Service) : **Port 53** - An Internet service that translates domain names into IP addresses.

  * **DHCP** (Dynamic Host Configuration Protocol) : **udp/67** - Automatically assigns IP addresses and network configuration information. The client computer requesting the address from the DHCP server sends the DHCP request to the server over udp/67 using a source of udp/68.

  * **HTTP** (Hypertext Transfer Protocol) : **TCP Port 80** - HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to commands.

  * **POP3** (Post Office Protocol 3) : **TCP Port 110** - POP3 is a protocol used to retrieve e-mail from a mail server.

  * **IMAP** (Internet Message Access Protocol) : **TCP Port 143** - Used for retrieving e-mail messages. Successor to POP3, IMAP4 is similar, but supports  server-based repositories of sent mail and other specialized folders.

  * **HTTPS** (Hypertext Transfer Protocol over Secure Socket Layer) : **TCP Port 443** - HTTPS is a Web protocol that encrypts and decrypts page requests and pages returned by the server.

  * **RDP** (Remote Desktop Protocol) : **Port 3389**