Ports and protocols
20, 21 - FTP - File Transfer Protocol
Provides insecure file transfers between a client and a server. Data is transmitted in clear, there is no encryption.
22 - SSH - Secure Shell
Provides secure remote control of another machine using a text-based environment (a command shell). It is best known for its remote logging capability and its use as an encrypted graphic network protocol. It uses encryption. It is safe to use over insecure networks.
22 - SFTP - Secure File Transfer Protocol
Provides secure file transfers. Essentially, it is tunnelling of FTP over SSH.
23 - Telnet
Same as SSH, but insecure. Provides by-directional interactive text-oriented communication usig virtual terminal connections. All data is sent in clear, without any encryption.
25 - SMTP - Simple Mail Transfer Protocol
Provides an ability to send emails over the network. It is an Internet standard for sending electronic messages over the network.
53 - DNS - Domain Name Service
Converts domain names to IP addresses and IP addresses to domain names.
67, 68 - DHCP - Dynamic Host Control Protocol
Automatically provides network parameters to clients, such as their assigned IP addresses, subnet mask, default gateway, and the DNS server they should use. Helps simplify network administration.
69 - TFTP - Trivial File Transfer Protocol
Used as a lightweight file transfer method for sending configuration files from a router or switch or for network booting of an OS. Used to transfer files in both directions of a client-server application. Does not provide any authentication. Basically, it is a simplified version of FTP.
80 - HTTP - Hypertext Transfer Protocol
Used for insecure web browsing.
110 - POP3 - Post Office Protocol v3
Used for receiving incoming emails by local email clients from remote servers over a TCP/IP connection. It is used only for inbound connections. Uses store-and-forward method of communication.
123 - NTP - Network Time Protocol
Used to keep accurate time for clients on a network. Synchronisation over packed switched variable latency data networks.
139 - NetBIOS - Network Basic Input/Ouptup System
Used for file or printer sharing over a Windows network.
143 - IMAP - Internet Mail Application Protocol
A newer method of retrieving incoming emails over a TCP/IP connection. IMAP improves upon the older POP3. Allows user to manipulate email messages on a remote server as if they are on a local machine. Keeps email status (like read/unread) synchronised across all the devices with client applications.
161, 162 - SNMP - Simple Network Management Protocol
Used to collect data about network devices and monitor their statuses (like uptime or downtime) over an IP network. Includes such devices as routers, switches, VoIP phones etc.
389 - LDAP - Lightweight Directory Access Protocol
Used to provide distributed information directory services to the network. Also, LDAP can store information about users and groups.
443 - HTTPS - Hypertext Transfer Protocol - Secure
Used for secure web browsing. Same as HTTP, but operates via an end-to-end encrypted tunnel between a client and a server which uses either SSL (Secure Socket Layer) or TLS (Transport Layer Security), TLS being a newer and more secure method.
445 - SMB - Secure Message Block
Used for Windows file and printer sharing services. Often operates in conjunction with NetBIOS. NetBIOS provides authentication, while SMB - actual data transfers.
514 - Syslog - System Logging Protocol
Used to send logging data back to a centalized server.
587 - SMTP TLS - Simple Mail Transfer Protocol Transport Layer Security
Secure and encrypted way to send emails. Essentially, encryption is added to SMTP traffic sent over port 25.
636 - LDAPS - Lightweight Directory Access Protocol - Secure
Provides secure directory services.
993 - IMAP over SSL - Internet Message Access Protocol over SSL
Secure and encypted way to receive emails.
995 - POP3 over SSL - Post Office Protocol v3 over SSL
Secure and encypted way to receive emails.
1433 - SQL - Structured Query Language Server Protocol
Used for communication from a client to a MS SQL Server.
1521 - SQLnet Protocol
Used for communication of a client to an Oracle database server.
3306 - MySQL
Used for communication of a client to a MySQL database engine.
3389 - RDP - Remote Desktop Protocol
Provides graphical remote control over another client or server. Proprietary protocol developed by Microsoft.
5060, 5061 - SIP - Session Initiation Protocol
Used to initiate VoIP and video calls. Provides signalling and controlling for media communication sessions. Used in VoIP, video, voice calls, as well as instant messaging.