Introduction to Networking

As an information security professional, a firm grasp of networking fundamentals and the required components is necessary. Without a strong foundation in networking, it will be tough to progress in any area of information security. Understanding how a network is structured and how the communication between the individual hosts and servers takes place using the various protocols allows us to understand the entire network structure and its network traffic in detail and how different communication standards are handled. This knowledge is essential to create our tools and to interact with the protocols.

Introduction

Networking Overview

Network - enables two computers to communicate with each other
/24 - allows computers to talk to each other as long as the first three octets
/25 - divides this range in half
Work From Home setup:

Networking - delivery of mail or packages sent by one computer and received by the other
Uniform Resource Locator (URL)/Fully Qualified Domain Name (FQDN) - website address which we enter into our browser
- URL - (https://www.hackthebox.eu/example?floor=2&office=dev&employee=17)
- FQDN - (www.hackthebox.eu)

Printer should not have been able to talk to the internet
Workstation should not have been able to communicate to the printer over port 445
Printer should not be able to initiate connections to workstations. In some cases, printer/scanner combinations should be able to communicate to a mail server to email scanned documents.

Networking Structure

Network Types

Network Type

Description

Wide Area Network (WAN)

Internet

Local Area Network (LAN)

Internal Networks (Ex: Home or Office)

Wireless Local Area Network (WLAN)

Internal Networks accessible over Wi-Fi

Virtual Private Network (VPN)

Connects multiple network sites to one LAN

Wide Area Network (WAN) - address that is generally accessed by the internet. Also, a large number of LANs joined together. It uses BGP.
Local Area Network (LAN)/Wireless Local Area Network (WLAN) - typically assigned IP addresses for local use.
Virtual Private Network (VPN)
- Site-To-Site VPN - share entire network ranges. Use to join network over the internet as same as local.
- Remote Access VPN - creating a virtual interface that behaves as if it is on a client's network
- SSL VPN - Typically these will stream applications or entire desktop sessions to your web browser

Network Type

Definition

Global Area Network (GAN)

Global network (the Internet)

Metropolitan Area Network (MAN)

Regional network (multiple LANs)

Wireless Personal Area Network (WPAN)

Personal network (Bluetooth)

Networking Topologies

Network Topology - is a typical arrangement and physical and logical connection of devices in a network

Computers are hosts, such as clients and servers, that actively use the network
They also include network components such as switches, bridges, and routers

Transmission Medium Layout - used to connect devices in the physical topology of the network e.g. for glass fiber media, this is cabling plan
Physical Topology - placement of nodes, how they connect using physical cables
Logical Topology - how signals act on the network media or how the data will be transmitted from one device to another
3 Areas of network topology
- Connections
Wired Connections
Wireless Connections
Coaxial cabling
Wi-Fi
Glass fiber cabling
Cellular
Twisted-pair cabling
Satellite
- Nodes - Network Interface Controller (NICs) - are the transmission medium's connection points to transmitters and receivers of electrical, optical, or radio signals in the medium.
  - Repeaters
  - Hubs
  - Bridges
  - Switches
  - Router/Modem
  - Gateways
  - Firewalls
- Classifications
  - Point-To-Point Topology - simplest topology of device. Direct and straightforward physical link exists between two host
  - Bus Topology - all hosts are connected in transmission medium. There is no central network component that control and process it, using coaxial cable
  - Star Topology - maintains a connection to all hosts. Each host is connected to a central network component via a separate link. And the central component will handle the forwarding function to pass the data to the destination
  - Ring Topology - is such that each host or node is connected to the ring with two cables. 1 for incoming and 1 for outgoing. Typically, the transmission medium is accessed sequentially from station to station using a retrieval system from the central station or a token. A token is a bit pattern that continually passes through a ring network in one direction, which works according to the claim token process
  - Mesh Topology - have no fixed topology.
    Fully Meshed - This means that the hosts are meshed with each other. used by WAN and MAN for reliability.
    Partially Meshed - the endpoints are connected by only one connection.
  - Tree Topology - is an extended star topology that more extensive local networks have in this structure.
  - Hybrid Topology - combination of two or more topologies that are interconnected
  - Daisy Chain Topology - multiple hosts are connected by placing a cable from one node to another. Used by CAN

Proxies

Proxy - when a device or service sits in the middle of a connection and acts as a mediator. It is on the Layer 7 of OSI model
Mediator - critical piece of information it means that the device sits in the middle and must be able to inspect the content of the traffic

Without a mediator, device is not a proxy. It is gateway.

Proxy Types
- Dedicated Proxy/Forward Proxy - is when a client makes a request to a computer, and that computer carries out the request. Filtering the outgoing requests. e.g. BurpSuite
- Reverse Proxy - reverse of Forward Proxy. Filtering incoming response. The most common goal with a Reverse Proxy, is to listen on an address and forward it to a closed-off network. e.g. ModSecurity, WAF
- (Non-) Transparent Proxy -
  - Transparent Proxy - the client doesn't know about its existence. Intercepts the client's communication requests to the Internet and acts as a substitute instance.
  - Non-transparent Proxy - we must be informed about its existence.

Networking Workflow

Networking Models

Communications has two networking model (ISO model and TCP/IP model)

OSI (Open Systems interconnect) Model - reference that can be describe and define as the communication between systems
TCP/IP (Transmission Control Protocol/Internet Protocol) Model - responsible for switching and transport of data packets on the internet

TCP/IP - is a communication protocol that allows hosts to connect to the internet and used by application
OSI - communication gateway between the network and end-users
Printer should not be able to initiate connections to workstations. In some cases, printer/scanner combinations should be able to communicate to a mail server to email scanned documents.

PDU (Protocol Data Unit) - In a layered system, devices in a layer exchange data in a different format

Encapsulation - During the transmission each layer adds header to PDU, which controls and identifies packet

OSI Model

The goal in defining the ISO/OSI standard was to create a reference model that enables the communication of different technical systems via various devices and technologies and provides compatibility

Layer

Description

Application

Among other things, this layer controls the input and output of data and provides the application functions.

Presentation

The presentation layer's task is to transfer the system-dependent presentation of data into a form independent of the application.

Session

The session layer controls the logical connection between two systems and prevents, for example, connection breakdowns or other problems.

Transport

Layer 4 is used for end-to-end control of the transferred data. The Transport Layer can detect and avoid congestion situations and segment data streams.

Network

On the networking layer, connections are established in circuit-switched networks, and data packets are forwarded in packet-switched networks. Data is transmitted over the entire network from the sender to the receiver.

Data Link

The central task of layer 2 is to enable reliable and error-free transmissions on the respective medium. For this purpose, the bitstreams from layer 1 are divided into blocks or frames.

Physical

The transmission techniques used are, for example, electrical signals, optical signals, or electromagnetic waves. Through layer 1, the transmission takes place on wired or wireless transmission lines.

Layers 2-4 - transport-oriented
Layers 5-7 - appication-oriented
To pass the data between devices, layers 7-1 (client) and layers 1-7 (server)

TCP/IP Model

IP is located in network layer or layer 3
IP is located in transport layer or layer 4

Application

The Application Layer allows applications to access the other layers' services and defines the protocols applications use to exchange data.

Trransport

The Transport Layer is responsible for providing (TCP) session and (UDP) datagram services for the Application Layer.

Internet

The Internet Layer is responsible for host addressing, packaging, and routing functions.

Link

The Link layer is responsible for placing the TCP/IP packets on the network medium and receiving corresponding packets from the network medium. TCP/IP is designed to work independently of the network access method, frame format, and medium.

IP ensures that the data packet reaches the destination IP
TCP ensures the the connection of data stream
To pass the data between devices, layers 7-1 (client) and layers 1-7 (server)

Task

Protocol

Description

Logical Addressing

Due to many hosts in different networks, there is a need to structure the network topology and logical addressing. Within TCP/IP, IP takes over the logical addressing of networks and nodes. Data packets only reach the network where they are supposed to be. The methods to do so are network classes, subnetting, and CIDR.

Routing

For each data packet, the next node is determined in each node on the way from the sender to the receiver. This way, a data packet is routed to its receiver, even if its location is unknown to the sender.

Error & Control Flow

TCP

The sender and receiver are frequently in touch with each other via a virtual connection. Therefore control messages are sent continuously to check if the connection is still established.

Application Support

TCP

TCP and UDP ports form a software abstraction to distinguish specific applications and their communication links.

Name Resolution

DNS

DNS provides name resolution through Fully Qualified Domain Names (FQDN) in IP addresses, enabling us to reach the desired host with the specified name on the internet.

Addressing

Network Layer

Network Layer/Layer 3 - controls exchange of data packets
Layer 3 responsible for these functions:
- Logical Addressing
- Routing
Protocols - represent a collection of rules for communication in the respective layer
- IPv4/IPv6
- IPsec
- ICMP
- IGMP
- RIP
- OSPF

IPv4 Addresses

Addressing network is done via IPv4/IPv6 address
IPv4/IPv6 - is the unique postal address and district of the receiver building
MAC - exact floor and apartment of receiver

It is possible for single IP address to address multiple receivers (broadcasting)

IPv4 - consists of 32-bit binary number combined into 4 bytes consisting 8-bit groups (octets) ranging from 0-255

Notation

Presentation

Binary

0111 1111.0000 0000.0000 0000.0000 0001

Decimal

127.0.0.1

Each network interface (network cards, network printers, or routers) is assigned through unique IP address
IPv4 allows 4,294,967,296 unique addresses
IPv4 has its own part, the network and host part

Class

Network Address

First Address

Last Address

Subnet Mask

CIDR

Subnets

IPs

1.0.0.0

1.0.0.1

127.255.255.255

255.0.0.0

127

16,777,214 + 2

128.0.0.0

128.0.0.1

191.255.255.255

255.255.0.0

/16

16, 384

65,534 + 2

192.0.0.0

192.0.0.1

223.255.255.255

255.255.255.0

/24

2, 097, 152

254+2

224.0.0.0

224.0.0.1

239.255.255.255

Multicast

240.0.0.0

240.0.0.1

255.255.255.255

reserved

Subnetting - separation of classes into small network
Subnet Mask - describes but positions which IP address act as network part or host part
Default Gateway - name of router in IPv4 addresses, common to the default gateway name the first or last assignable to IPv4 address
Broadcast Address - connect all devices to in a network with each other
Broadcast - message in a network transmitted to all participants, last IPv4 address is used for that
Binary system - system that uses only 1 and 0

IPv4 is divided into 4 octets and each octet contains 8 bits. eg. 192.168.10.39

Example IP address: 192.168.10.39
1st Octet Value: 192

Values:         128  64  32  16  8  4  2  1
Binary:           1   1   0   0  0  0  0  0

2nd Octet Value: 168
3rd Octet Value: 10
4th Octet Value: 39

Octet

Values

Sum

1st

128 + 64 + 0 + 0 + 0 + 0 + 0 + 0

192

2nd

128 + 0 + 32 + 0 + 8 + 0 + 0 + 0

168

3rd

0 + 0 + 0 + 0 + 8 + 0 + 2 + 0

4th

0 + 0 + 32 + 0 + 0 + 4 + 2 + 1

IPv4 Binary Notation - 192.168.10.39

Octet:             1st         2nd         3rd         4th
Binary:         1100 0000 . 1010 1000 . 0000 1010 . 0010 0111
Decimal:           192    .    168    .     10    .     39

IPv4 - Decimal to Binary of Class C

Values:         128  64  32  16  8  4  2  1
Binary:           1   1   1   1  1  1  1  1

Octet

Values

Sum

1st

128 + 64 + 32 + 16 + 8 + 4 + 2 + 1

255

2nd

128 + 64 + 32 + 16 + 8 + 4 + 2 + 1

255

3rd

128 + 64 + 32 + 16 + 8 + 4 + 2 + 1

255

4th

0 + 0 + 0 + 0 + 0 + 0 + 0 + 0

Subnet Mask

Octet:             1st         2nd         3rd         4th
Binary:         1111 1111 . 1111 1111 . 1111 1111 . 0000 0000
Decimal:           255    .    255    .    255    .     0

Classless Inter-Domain Routing (CIDR) - is a method of representation and replaces the fixed assignment between IPv4 address and network classes (A, B, C, D, E)
CIDR suffix - division is based on subnet mask
IPv4: 192.168.10.39
Subnet Mask: 255.255.255.0
CIDR: 192.168.10.39/24

Octet:             1st         2nd         3rd         4th
Binary:         1111 1111 . 1111 1111 . 1111 1111 . 0000 0000 (/24)
Decimal:           255    .    255    .    255    .     0

Subnetting

Subnetting - division of an address range in IPv4 addresses into smaller address range
Subnet - logical statement of a network that uses IP addresses with same network addresses

We can create a subnet from these outlines:

Network address
Broadcast address
First host
Last host Number of hosts

Example:
- IPv4 Address: 192.168.12.160
- Subnet Mask: 255.255.255.192
- CIDR: 192.168.12.160/26
Network Part (All yellow)

Details

1st Octet

2nd Octet

3rd Octet

4th Octet

Decimal

IPv4

1100 0000

1010 1000

0000 1100

1010 0000

192.168.12.160/26

Subnet Mask

1111 1111

1100 0000

255.255.255.192

Bits

/16

/24

/32

Host Part (All yellow)

Details

1st Octet

2nd Octet

3rd Octet

4th Octet

Decimal

IPv4

1100 0000

1010 1000

0000 1100

1010 0000

192.168.12.160/26

Subnet Mask

1111 1111

1100 0000

255.255.255.192

Bits

/16

/24

/32

Network Address - vital for delivery of packet
Subnet Mask - determine where separation occurs
Separation of Network and Host Parts:

Details

1st Octet

2nd Octet

3rd Octet

4th Octet

Decimal

IPv4

1100 0000

1010 1000

0000 1100

10 | 10 0000

192.168.12.160/26

Subnet Mask

1111 1111

11 | 00 0000

255.255.255.192

Bits

/16

/24

/32

Under 4th Octet 10| is the part of network address, make host part all 0's -> 10 | 00 0000, so the network address wil be 192.168.12.128
Under 4th Octet |10 0000 is the part of host address, make host part all 1's -> 10 | 11 1111, so the broadcast address wil be 192.168.12.191

Hosts

IPv4

Network Address

192.168.12.128

First Host

192.168.12.129

Other Hosts

...

Last Host

192.168.12.190

Broadcast Address

192.168.12.191

Subnet in to smaller networks use this -> 2^n = value
Example:
- Subnet: 192.168.12.128/26
- Required subnets: 4
To get the 2 bits, 2^2 = 4, n = 2
Increase the CIDR to 2 bits /26 + 2 = /28 (changes all in yellow)

Details

1st Octet

2nd Octet

3rd Octet

4th Octet

Decimal

IPv4

1100 0000

1010 1000

0000 1100

1010 | 0000

192.168.12.160/28

Subnet Mask

1111 1111

1111 | 0000

255.255.255.240

Bits

/16

/24

/32

64 divide 4 subnets = 64 / 4 = 16 host range

Subnet no.

Network Address

First Usable Host

Last Usable Host

Broadcast Adress

CIDR

192.168.12.128

192.168.12.129

192.168.12.142

192.168.12.143

192.168.12.128/28

192.168.12.144

192.168.12.145

192.168.12.158

192.168.12.159

192.168.12.144/28

192.168.12.160

192.168.12.161

192.168.12.174

192.168.12.175

192.168.12.160/28

192.168.12.176

192.168.12.177

192.168.12.190

192.168.12.191

192.168.12.176/28

SHORTCUT ON SUBNETTING

Get the CIDR value of given IPv4 Address and get the remainder when dividing by 8 (modulo)
Subtract 8 to 3
Raise 2 to the difference of CIDR value and 3
The value you get minus 1
Add this to the given IPv4 address and that is the range
If the problem has subnets, divide the range to given subnets

Example:

IPv4 address: 10.200.20.0/27
Subnet: 4

Steps:

/27 is the CIDR value, get the remainder = 27 % 8 = 3
Subtract 8 to 3 (ALWAYS 8-n, IT IS FIXED) = 8 - 3 = 5
Raise 2 to 5 (ALWAYS 2^n, IT IS FIXED) = 2 ^ 5 = 32
Subtract the value to 1 (ALWAYS n-1, IT IS FIXED) = 32 - 1 = 31
Add the host value to base IPv4 address = 10.200.20.0 = 0 + 31 = 31 = 10.200.20.0 to 10.200.20.31

If the given has subnet (OPTIONAL):

To get the subnets, divide 32 (IN THE STEP 3), to given subnet 4 = 32 / 4 = 8
Subtract the value to 1 (ALWAYS n-1, IT IS FIXED) = 8 - 1 = 7
Add the host address 10.200.20.0 to 7 = 0 + 7 = 7 = 10.200.20.0 to 10.200.20.7 (FIRST SUBNET)
Add the host address 10.200.20.8 to 7 = 8 + 7 = 15 = 10.200.20.8 to 10.200.20.15 (SECOND SUBNET)
Add the host address 10.200.20.16 to 7 = 16 + 7 = 23 = 10.200.20.16 to 10.200.20.23 (THIRD SUBNET)
Add the host address 10.200.20.24 to 7 = 24 + 7 = 31 = 10.200.20.24 to 10.200.20.31 (FOURTH SUBNET)

To visualize:

Range IPv4 Address: 10.200.20.0 to 10.200.20.31
Subnets: 4

Subnet no.

Network Address

First Usable Host

Last Usable Host

Broadcast Adress

CIDR

10.200.20.0

10.200.20.1

10.200.20.6

10.200.20.7

10.200.20.0/27

10.200.20.8

10.200.20.9

10.200.20.14

10.200.20.15

10.200.20.8/27

10.200.20.16

10.200.20.17

10.200.20.22

10.200.20.23

10.200.20.16/27

10.200.20.24

10.200.20.25

10.200.20.30

10.200.20.31

10.200.20.24/27

Questions:

1. Submit the decimal representation of the subnet mask from the following CIDR: 10.200.20.0/27

255.255.255.224

2. Submit the broadcast address of the following CIDR: 10.200.20.0/27

10.200.20.31

3. Split the network 10.200.20.0/27 into 4 subnets and submit the network address of the 3rd subnet as the answer.

10.200.20.16

4. Split the network 10.200.20.0/27 into 4 subnets and submit the broadcast address of the 2nd subnet as the answer.

10.200.20.15

MAC Addresses

Each host in a network has its own 48-bit (6 octets) MAC address

Media Access Control (MAC) address - physical address for our network interfaces
Several different standards of MAC:
- Ethernet (IEEE 802.3)
- Bluetooth (IEEE 802.15)
- WLAN (IEEE 802.11)
Example of MAC address:
- DE:AD:BE:EF:13:37
- DE-AD-BE-EF-13-37
- DEAD.BEEF.1337

Representation

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

6th Octet

Binary

1101 1110

1010 1101

1011 1110

1110 1111

0001 0011

0011 0111

Hex

The packet is must addressed in layer 2 to destination which is responsible for routing. Each packet has source and destination address.

MAC address consist of total of 6 bytes

Representation

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

6th Octet

Binary

1101 1110

1010 1101

1011 1110

1110 1111

0001 0011

0011 0111

Hex

Organization Unique Identifier (OUI) (Yellow) - first half of the address (3 bytes/24 bits)
Individual Address Part or Network Interface Controller (NIC) (Red) - last half, assigned by manufacturers

If a IP address in on the same subnet, it will directly deliver to the host. On the other hand, if host is on the different subnet, the Ethernet frame is addressed to MAC address of the router (default gateway)
If Ethernet frame's destination address matches its own layer 2 address, the router will forward it to upper layers

Address Resolution Protocol (ARP) - is used in IPv4 to determine the MAC addresses associated with the IP addresses
Reserved MAC addresses called Local Range:
- 02:00:00:00:00:00
- 06:00:00:00:00:00
- 0A:00:00:00:00:00
- 0E:00:00:00:00:00
MAC Unicast - last 2 bits in the first octet signifies if the address is Unicast (0) or Multicast (1) (Yellow), packet sent will reach only 1 specific host, last bit in 1st octet is 0

Representation

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

6th Octet

Binary

1101 1110

1010 1101

1011 1110

1110 1111

0001 0011

0011 0111

Hex

MAC Multicast - packet is sent only once to all hosts, last bit in 1st octet is 1 (Yellow)

Representation

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

6th Octet

Binary

0000 0001

0000 0000

0101 1110

1110 1111

0001 0011

0011 0111

Hex

MAC Broadcast - data packets is sent to all members of a network, All 1 (Yellow)

Representation

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

6th Octet

Binary

1111 1111

Hex

Global OUI - second to last bit of first octet is 0

Representation

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

6th Octet

Binary

1101 1100

1010 1101

1011 1110

1110 1111

0001 0011

0011 0111

Hex

Locally Administered - second to last bit of first octet is 1

Representation

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

6th Octet

Binary

1101 1110

1010 1101

1011 1110

1110 1111

0001 0011

0011 0111

Hex

Address Resolution Protocol (ARP) - is a network protocol used to resolve network layer (layer 3) IP address to link layer (layer 2) MAC address to facilitate LAN
ARP Resolution - device with matching IP address responds with its own MAC address, and then the 2 devices can communicate directly using their MAC address
ARP Request - request is broadcast to all devices in a LAN and it contains the IP address of the destination
ARP Reply - when device receives ARP request, it sends an ARP Reply to the requesting device with its MAC address

1st and 3rd lines, indicates that device of is requesting a MAC address for specied IP address
2nd and 4th lines, shows ARP reply to that request
This is vulnerable to ARP spoofing

ARP Spoofing - used to intercept or manipulate traffic on the network, secure using firewall or IDS, attack in which we send falsified ARP messages to LAN (Pretend like a legitimate address), can be done using Ettercap or Cain & Abel

1st and 4th lines, shows 10.129.12.100 sending falsified ARP messages to the target, associating its MAC address to 10.129.12.101
2nd and 3rd lines, show the target sending an ARP request and replying to our MAC address. Also, indicates that we have poisoned the target's ARP cache and that all traffic intended for the target will now be sent to our MAC address.

IPv6 Addresses

IPv6 - successor of IPv4, 128 bit long
prefix - identifies the host and network parts
Internet Assigned Numbers Authority (IANA) - responsible for IPv4 and IPv6 addresses
Dual Stack - IPv4 and IPv6 can be made available simultaneously
Advantages of IPv6:
- Larger Address Space
- Address self-configuration (SLAAC)
- Multiple IPv6 addresses per interface
- Faster Routing
- End-to-end encryption (IPsec)
- Data packages up to 4 GByte

Features

IPv4

IPv6

Bit length

32-bit

128-bit

OSI layer

Network Layer

Addressing range

~ 4.3 billion

~ 340 undecillion

Representation

Binary

Hexadecimal

Prefix notation

10.10.10.0/24

fe80::dd80:b1a9:6687:2d3b/64

Dynamic Addressing

DHCP

SLAAC / DHCPv6

IPsec

Optional

Mandatory

4 different types of IPv6
- Unicast - addresses for single interface
- Anycast - addresses for multiple interface, one of them receives the packet
- Multicast - addresses for multiple interface, all receives same packet
- Broadcast - do not exist and realized with multicast addresses
Hexadecimal System (hex) - make the binary more readable, 16 (0-F)

Representation

1st Octet

2nd Octet

3rd Octet

4th Octet

Binary

1100 000

1010 1000

0000 1100

1010 0000

Hex

Decimal

192

168

160

IPv6 contains 16 bytes/128-bit
IPv6 separated by colon (:)
Full IPv6: fe80:0000:0000:0000:dd80:b1a9:6687:2d3b/64
Short IPv6: fe80::dd80:b1a9:6687:2d3b/64

IPv4 parts
- Network Prefix (network part) - identifies the network, range and subnet
- Interface Identifier/Suffix (host part) - formed from 48-bit MAC address, default prefix length is /64

In RFC 5952, IPv6 address notation should:

All alphabetical characters are always written in lower case
All leading zeroes are omitted
1 or more consecutive blocks of 4 zeroes are shortened by two colons (::)
The shortening of two colons may only performed once starting left

Protocols & Terminology

Networking Key Terminology

Protocol

Acronym

Description

Wired Equivalent Privacy

WEP

security protocol commonly used to secure wireless networks

Secure Shell

SSH

secure network protocol to log into and execute commands in a remote host

File Transfer Protocol

FTP

network protocol used to transfer files in a network

Simple Mail Transfer Protocol

SMTP

protocol used to send and receive emails

Hypertext Transfer Protocol

HTTP

client-server protocol to send and receive data over the internet

Server Message Block

SMB

protocol used to share files, printers, and other resources in a network

Network File System

NFS

protocol used to access file in a network

Simple Network Management Protocol

SNMP

protocol used to managed network devices

Wi-Fi Protected Access

WPA

wireless security protocol to protect wireless networks in an unauthorized access

Temporal Key Integrity Protocol

TKIP

security protocol used in wireless networks but less secure

Network Time Protocol

NTP

to synchronize time in a network

Virtual Local Area Network

VLAN

way to segment network into multiple logical networks

VLAN Trunking Protocol

VTP

layer 2 protocol used to establish and maintain a VLAN spanning multiple switches

Routing Information Protocol

RIP

distance-vector routing protocol used in LANs and WANs

Open Shortest Path First

OSPF

an IGP for routing traffic within a single Autonomous System in an IP network

Interior Gateway Routing Protocol

IGRP

Cisco proprietary protocol designed for routing Autonomous System

Enhanced Interior Gateway Routing Protocol

EIGRP

advanced distance-vector routing protocol that is used to route IP traffic in a network

Pretty Good Privacy

PGP

encryption program used to secure emails, files and other types of data

Network News Transfer Protocol

NNTP

used for distributing and receiving messages in a newsgroup across the internet

Cisco Discovery Protocol

CDP

Cisco proprietary protocol that allows administrators to discover and manage cisco devices in a network

Hot Standby Router Protocol

HSRP

protocol used in Cisco devices to provide redundancy when router or network devices fail

Virtual Router Redundancy Protocol

VRRP

protocol used to provide automatic assignment of available IP router in a host

Spanning Tree Protocol

STP

used to ensure loop-free topology in Layer 2 ethernet networks

Terminal Access Controller Access-Control System

TACACS

protocol that provides centralized authentication, authorization, and accounting for network access

Session Initiation Protocol

SIP

signaling protocol used for establishing and terminating real-time voice, video and multimedia sessions in an IP network

Voice Over IP

VOIP

technology used to create telephone calls over internet

Extensible Authentication Protocol

EAP

framework for authentication that supports multiple authentication methods, such as passwords, digital certificates, one-time passwords, and public-key authentication

Lightweight Extensible Authentication Protocol

LEAP

Cisco proprietary wireless authentication protocol, based on EAP used in Point-to-Point Protocol

Protected Extensible Authentication Protocol

PEAP

security protocol that provides encrypted tunnel for wireless networks

Systems Management Server

SMS

systems management solution that helps organitions manage their networks, systems and mobile devices

Microsoft Baseline Security Analyzer

MBSA

a Microsoft tool used to monitor and detect security vulnerabilities within Windows computers

Supervisory Control and Data Acquisition

SCADA

type of industrial control system to monitor and control industrial processes

Virtual Private Network

VPN

technology that allows to create and secure encrypted connection to a network over the internet

Internet Protocol Security

IPsec

protocol that provides secured and encrypted communication over the network

Point-to-Point Tunneling Protocol

PPTP

protocol used to create a secure, encrypted tunnel for remote access

Network Address Translation

NAT

technology that translates private IP addresses into single public address

Carriage Return Line Feed

CRLF

Combines two control characters to indicate the end of a line and a start of a new one for certain text file formats

Asynchronous JavaScript and XML

AJAX

technique used to create dynamic web pages using JavaScript and XML/JSON

Internet Server Application Programming Interface

ISAPI

allows to create performance-oriented web extensions for web servers using a set of APIs.

Uniform Resource Identifier

URI

syntax to identify a resource on internet

Uniform Resource Locator

URL

subset of URI, including the protocol and domain name

Internet Key Exchange

IKE

protocol used in VPNs to provide authentication and encryption for data transmission and protect data from tampering and eavesdropping

Generic Routing Encapsulation

GRE

protocol used to encapsulate data transmitted within the VPN tunnel

Remote Shell

RSH

program under Unix that allows executing commands and programs on a remote computer

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Last updated 1 year ago