Protocols and Ports

Secure Shell (SSH)

Encrypted remote login protocol, typically on TCP port 22.

Secure File Transfer Protocol (SFTP)

File transfer protocol that runs over SSH (port TCP/22), providing secure transfers.

Telnet

Remote terminal protocol that transmits in plaintext; insecure and largely deprecated.

Simple Mail Transfer Protocol (SMTP)

Protocol for sending email between servers; TCP port 25 (plaintext) and 587 (TLS encryption).

Domain Name System (DNS)

Translates domain names into IP addresses; typically uses UDP port 53 (TCP for zone transfers).

Dynamic Host Configuration Protocol (DHCP)

Assigns IP addresses and network settings automatically to devices; uses UDP ports 67/68.

DHCP Reservation

A DHCP feature that ensures a device always receives the same IP address.

Dynamic DHCP

Standard DHCP operation where Ips are leased temporarily from a pool.

Trivial File Transfer Protocol (TFTP)

Simplified, unsecured file transfer protocol using UDP port 69.

Hypertext Transfer Protocol (HTTP)

Protocol for transferring web pages and content; TCP port 80.

Hypertext Transfer Protocol Secure (HTTPS)

Encrypted version of HTTP, using TLS/SSL; TCP port 443.

Network Time Protocol (NTP)

Protocol for synchronizing clocks across systems; UDP port 123.

Simple Network Management Protocol (SNMP)

Used for managing and monitoring devices on a network; UDP ports 161/162.

Lightweight Directory Access Protocol (LDAP)

Protocol for accessing and managing directory services; TCP/UDP port 389.

Lightweight Directory Access Protocol Secure (LDAPS)

Encrypted LDAP using SSL/TLS; TCP port 636.

Server Message Block (SMB)

Protocol for sharing files, printers, and other resources on Windows networks; TCP port 445.

Syslog

Standard for logging system and network messages; typically UDP port 514.

Microsoft SQL Server

Database server protocol; commonly TCP port 1433.

Remote Desktop Protocol (RDP)

Protocol for remote graphical access to Windows desktops; TCP port 3389.

Session Initiation Protocol (SIP)

Protocol for initiating, managing, and ending VoIP calls and multimedia sessions; TCP ports 5060/5061

Internet Control Message Protocol (ICMP)

Protocol used for network diagnostics and error reporting (e.g., ping, traceroute).

Generic Routing Encapsulation (GRE)

A tunneling protocol that encapsulates packets for transport across networks, often used with VPNs.

VPN Concentrator

A dedicated device that manages and secures VPN connections for multiple users.

Site-to-Site VPN

A VPN that securely connects entire networks (e.g., branch office) over the internet.

Internet Protocol Security (IPSec)

A suite of protocols that secures IP communications using encryption and authentication.

Authentication Header (AH)

An IPSec component that provides authentication and integrity, but not encryption.

Encapsulation Security Payload (ESP)

An IPSec component that provides authentication, integrity, and encryption of data.

Transport Mode

IPSec mode that encrypts only the payload of an IP packet, leaving the header intact.

Tunnel Mode

IPSec mode that encrypts the entire IP packet and adds a new header for routing.

Internet Key Exchange (IKE)

Protocol used in IPSec to establish secure keys and negotiate security associations.

Unicast

One-to-one communication between a single sender and a single receiver.

Multicast

One-t0-many communication where data is routed to the nearest device in a group.

Anycast

One-to-one-of-many communication where data is routed to the nearest device in a group.

Broadcast

One-to-all communication where data is sent to every device in a network segment.

802.11

IEEE standard for wireless LAN networking (Wi-Fi).