Computer Protocols

By Jo Blitz Escotal

Protocol -Set of rules or language use by computer and networking devices to communicate with one another.

Service – A service is use by computer and networking devices such as DNS, DHCP, Fax, file and print services. A service is software that performs tasks, respond to computer events, or listen to data requests from other software.

Here are the most well-known computer protocols

Networking Protocols

TCP/IP – Abbreviation for Transmission Control Protocol/Internet Protocol, the suite of communications protocols used to connect hosts on the Internet. TCP/IP uses several protocols, the two main ones being TCP and IP. TCP/IP is built into the UNIX operating system and is used by the Internet, making it the de facto standard for transmitting data over networks. TCP/IP uses an IP address a series of numbers divided by a dot example  TCP/IP is a connection oriented protocol.

UDP – User Datagram Protocol is a streamline economy class version of TCP which is connectionless but is very unreliable compared with TCP which is connection oriented protocol.

IPX/SPX – Internet Network Packet Exchange/Sequential Packet Exchange the Native protocol use by an older Novell Netware Networks

NetBEUI– Pronounced net-booey, NetBEUI is short for NetBios Enhanced User Interface. It is an enhanced version of the NetBIOS protocol used by network operating systems such as LAN Manager, LAN Server, and Windows for Workgroups, Windows 9 xs and Windows NT. NetBEUI does not support routing and thus cannot communicate in the Internet.

Apple Talk – Protocols use by older Apple computers

DLC Short for Data Link Control, an older protocol use to communicate with Mainframe computers and some older HP network laser printers.

NWLINK– Netware Link developed by Microsoft to communicate with Older Novell Netware networks

Dial Up and Remote Access Networking Protocols

PPP Short for Point-to-Point Protocol, a method of connecting to a computer to the Internet PPP is more stable than the older SLIP protocol and provides error-checking features.

SLIP-Short for Serial Line Internet Protocol, a method of connecting to the Internet another more common method is PPP (Point-to-Point Protocol). SLIP is an older and simpler protocol, but from a practical perspective, there’s not much difference between connecting to the Internet via SLIP or PPP. In general, service providers offer only one protocol although some support both protocols.

RAS – Dial up Protocol service use for connecting to a Microsoft Remote Access Server

RRAS – Routing and Remote Access Protocol

PPPoE– Point to Point Protocol over Ethernet used for connecting multiple network users on an Ethernet LAN to a remote site through a common device. Very popular with DSL and wireless

Transferring File Protocols

FTP – Abbreviation of File Transfer Protocol, the protocol used on the Internet for connection oriented transferring of files. Popular protocol for uploading and downloading pages

SFTP – Secure File Transfer Protocol use for transferring files in a secure manner

TFTP – Trivial File Transfer Protocol is a connectionless FTP as opposed to FTP which is connection oriented

World Wide Web Protocol

HTTP – Short for Hypertext Transfer Protocol, the underlying protocol used by the World Wide Web. It lets the browser communicate with the web server.

HTTPS – HTTP Secure with built in SSL/TLS (Encryption)

Newsgroup Protocols

NNTP – Short for Network News Transfer Protocol, the protocol used to post, distribute, and retrieve USENET, BBS or newsgroup materials

Directory protocols

LDAP – Short for Lightweight Directory Access Protocol, a set of protocols for accessing information directories. LDAP is based on the standards contained within the X.500 standard but is significantly simpler.

SLDAP – Secure Lightweight Directory Access Protocol

E-Mail Protocols

POP3– Short for Post Office Protocol version 3, the protocol used for receiving incoming e-mail.

POP3/S – POP3 Secure

SMTP – Short for Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers.

SMTP/S – SMTP Secure

IMAP4 – Internet Messaging Protocol version 4 use by mail clients to retrieve e-mail from a mail server

IMAP4/S – IMAP4 Secure

Host Management Protocols

DHCPDynamic Host Configuration Protocol a method for automatically assigning IP addresses to client computers on a network

BOOTP– Short for Bootstrap Protocol, an Internet Protocol that enables a diskless workstation to discover its own IP address, the IP address of a BOOTP server on the network, and a file to be loaded into memory to boot the machine

Name Translation Protocols

DNSDomain Name Service– A protocol that translates HOST names to IP address


WINS-Windows Internet Name Service a TCP/IP network service for MS Networks that resolves Net BIOS names and facilitates browsing across sub networks the manual file is called LMHOSTS

Routing Protocols

RIP – Routing Information Protocol (RIP) is one of the most commonly used routing protocols on internal networks (and to a lesser extent, networks connected to the Internet) which helps routers dynamically adapt to changes of network connections by communicating information about which networks each router can reach and how far away those networks are

OSPF – The Open Shortest Path First (OSPF) protocol is a link state hierarchical interior gateway protocol (IGP) for network routing. Algorithm is used to calculate the shortest path first. It uses cost as its routing metric. A link state database is constructed of the network topology which is identical on all routers in the area

IS-IS – Intermediate system to intermediate system (IS-IS), is a link state protocol used by network devices (routers) to determine the best way to forward data-grams through a packet-switched network, a process called routing.

BGP – Border Gateway Protocol when two systems are using BGP, they establish a TCP connection, and then send each other their BGP routing tables. BGP uses distance vectoring.

EGP – Exterior Gateway Protocol is used between routers of different systems.

IGP – Interior Gateway Protocol The name used to describe the fact that each system on the internet can choose its own routing protocol. RIP and OSPF are interior gateway protocols.

EIGRP – Enhanced Interior Gateway Routing Protocol is a Cisco proprietary routing protocol. EIGRP is an advanced distance-vector routing protocol, with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of bandwidth and processing power in the router.

Networking Management Protocols

SNMP – Simple Network Management Protocol (service protocol use for managing and monitoring networks) Supports SNMP Management Systems, Provides SNMP agents and MIB. SNMP V3 supports authentication and encryption.

ICMP – Internet Control Messaging Protocol which is a suite use to PING another host

ARP – Address Resolution Protocol is a network layer protocol that resolves network IP address into MAC addresses

RARP – Reverse Address Resolution Protocol is a network layer protocol that resolves MAC addresses to IP addresses

Multicasting Protocol

IGMP – Internet Group Multicast Protocol is use to send multicast group membership to adjacent routers. Multicast is communication between a single sender and multiple receivers on a network. Typical uses include the updating of mobile personnel from a home office and the periodic issuance of online newsletters.

Networking Service Protocols

Telnet – Telecommunication Network is a terminal emulation service use to connect to another host

SSH – Secure Shell is an application program use to log into another computer over a network

NTP – Network Time Protocol is a standard application protocol that sets computer clocks to a standard time source.

LPD/LPR – Line Printer Daemon/Line Printer Remote Protocol originally developed for and used on UNIX systems. This is a printer service/protocol that uses TCP/IP to establish connections between printers and computers on the network

 – Internet Connection Sharing is a method for connecting multiple computers in a LAN to the Internet through a single connection utilizing a single IP address

SCP – Secure Copy Protocol is a program that copies files between hosts on a network

NAT – Network Address translation is used in computer networking, NAT is also known as network masquerading or IP-masquerading) is a technique in which the source and/or destination addresses of IP packets are rewritten as they pass through a router or firewall. It is most commonly used to enable multiple hosts on a private network to access the Internet using a single public IP address. Variations of NAT includes PAT (Port Address Translation and SNAT Static Network Address Translation)

SMB – Server Message Block is an application-level network protocol mainly applied to shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an authenticated Inter-process communication mechanism.

AFP – Apple File Protocol is use by Non-Apple networks to access data on an Apple Talk Server

Samba – Provides file and print services to SMB clients. An open source version of the SMB file sharing protocol originally developed for UNIX also runs on Linux

RDP – Remote Desktop Protocol use in conjunction with terminal services provides a way for a client system to connect to a server

MPLS – Multiprotocol Label Switching is a mechanism in high-performance telecommunications networks which directs and carries data from one network node to the next. MPLS makes it easy to create “virtual links” between distant nodes. It can encapsulate packets of various network protocols.

Zeroconf or Zero Configuration Networking is a set of techniques that automatically create a usable IP network without configuration or special servers.

Voice IP Protocols

RTP – The Real-time Transport Protocol (RTP) defines a standardized packet format for delivering audio and video over the Internet.

SIP – The Session Initiation Protocol (SIP) is a signaling protocol, widely used for controlling multimedia communication sessions such as voice and video calls over Internet Protocol (IP).

H.323 – H.323 defines the protocols to provide audio-visual communication sessions on any packet network. The H.323 standard addresses call signaling and control, multimedia transport and control, and bandwidth control for point-to-point and multi-point conferences

Secure Protocols

SSL – Short for Secure Sockets Layer, a protocol developed by Netscape for transmitting private documents via the Internet. SSL works by using a public key to encrypt data that’s transferred over the SSL connection.

TLS – Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide security for communications over networks such as the Internet.

IPSec – IP Security protocol is designed to provide secure communications between systems.

PPTP Short for Point-to-Point Tunneling Protocol, a new technology use for creating a Virtual Private Networks (VPN’s)

L2TP Short for Layer Two (2) Tunneling Protocol, an extension to the PPP protocol that enables ISP’s to operate Virtual Private Networks (VPN’s)

WEP – WEP stands for Wired Equivalent Privacy. This is a security protocol for Wi-Fi networks. WEP was designed to provide the same level of security that a wired network provides. It provides security by encrypting data over the radio waves.

WPA – Stands for “Wi-Fi Protected Access.” WPA is a security protocol designed to create secure wireless networks. It is similar to the WEP protocol but offers improvements in the way it handles security keys, and the way users are authorized. WPA use Temporary Key Integrity Protocol TKIP and
WPA2/WPA3 uses Advanced Encryption Standards, AES the most popular encryption in wireless.

WTLS – Wireless Transport Layer Security is a component in the Wireless Application Protocol (WAP) protocol stack. It sits between the WTP and WDP layers in the WAP communications stack.

Authentication Protocols

CHAP – Challenge Handshake Authentication Protocol – CHAP is a weak one way authentication protocol use in RAS and some PPP connections

MS-CHAP – MS Challenge Handshake Authentication Protocol – Offers more security than CHAP use by Microsoft it supports version v1 and v2.

PAP – Password Authentication Protocol –PAP is the weakest authentication protocol that sends username and password in clear text form with no encryption over RAS.

SPAP- Shiva Password Authentication Protocol – A proprietary version of PAP used to connect to RAS servers manufactured by the Shiva Corporation

RADIUS – Remote Authentication Dial-In User Services – Industry standard authentication protocol that provides authorization, authentication and accounting services. NPS – Network Policy Server is RADIUS in a Windows Server Environment.

TACACS – Terminal Access Controller Access-Control System is a remote authentication protocol that is used to communicate with an authentication server commonly used in UNIX networks.

EAP – Extensible Authentication Protocol a general protocol that provides support for several different authentication protocols often use by wireless devices. (EAP-TLS) uses certificates for user authentication such as smart cards often use with laptops.

Kerberos – is a strong secure network authentication protocol designed and created at MIT that creates a TGS – Ticket Granting Service.

PKI – The Public Key Infrastructure (PKI) is a set of hardware, software, people, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates.

AAA – In computer security, AAA commonly stands for “authentication, authorization and accounting”. This is a misnomer, and should have been “authentication, access control and accounting”.

ISAKMP – Internet Security Association and Key Management Protocol is a protocol for establishing security in cryptographic systems.  This provides a framework for authentication and key exchange and is designed to be key independent.