Network and Security Flashcards
Wireless Access Point
-Extends a wired network to wireless connections
-Involves the IEEE 802.11 group of standards that defines wireless LAN’s {WLAN’s}
-Central connecting point for computers equipped with wireless network adapters
-Identifies each computer by its MAC address
Network Interface Layer
This layer establishes how data should be physically sent through the network
Session Layer (Layer 5)
This layer is responsible for connection establishment, session maintenance, and authentication.
Presentation Layer (Layer 6)
This layer is responsible for translating data from the application layer into the format required to transmit the data over the network as well as encrypting the data for security if encryption is used.
Hub (Physical Layer)
-The simplest device used on an Ethernet network for connecting devices to each other.
-Split the bandwidth of a connection among all the computers connected to it
-Does not perform any packet filtering or addressing functions but instead broadcasts data to all computers connected to it
Switch (Data and Network Layer)
-Provides connectivity to devices in a local network
-Creates a dedicated full-speed connection between two computers that are communicating with each other
-Makes use of the MAC address to deliver the message to the right destination
Router (Network Layer)
-Interconnect two or more networks
-Operates at the border of your network
-Stores information about the systems that are connected to it and where to send requests when the destination is unknown
-Works at the network layer of the OSI model
Patch panel
-A box designed as a junction point for twisted pair (TP) cable and fiber cable sed in networks
-First step in organizing your cables
Firewall
-A security hardware appliance or software application that protects a computer or network from unwanted intrusion
-Blocks unwanted connections from untrusted networks and can block basic network attacks
Modem (Physical and Data Link Layer)
-Connects a LAN to an internet service provider
-Converts digital signals into analog signals and vice versa.
TCP/IP
Transmission Control Protocol/Internet Protocol
Application Layer
This layer is responsible for the communication protocols between nodes. The protocols in this layer include hypertext transfer protocol (HTTP and HTTPS), Secure Shell (SSH), and Network Time Protocol (NTP), among many others.
Transport Layer
This layer is responsible for the end-to-end transport of data. The protocols that live in this layer are transmission control protocol (TCP) and user datagram protocol (UDP)
Network Layer
This layer defines the logical transmission protocols for the whole network. The main protocols that live in this layer are internet protocol (IP), Internet Control Message Protocol (ICMP), and Address Resolution Protocol (ARP).
OSI Model
Open Systems Interconnection Model
Physical Layer (Layer 1)
This layer is responsible for the physical connections of the devices in the network. This layer is implemented through the use of devices such as hubs, repeaters, modem devices, and physical cabling.
Data Link Layer (Layer 2)
This layer is responsible for the error-free delivery of data to the receiving device or node. This layer is implemented through the use of devices such as switches and bridge devices, as well as anything with a network interface, like wireless or wired network cards.
Network Layer (Layer 3)
This layer is responsible for the transmission of data between hosts in different networks as well as routing of data packets. This layer is implemented through the use of devices such as routers and some switches.
Transport Layer (Layer 4)
In this layer protocols ensure that data is transferred from point A to point B reliably and without errors. This layer services include flow control, acknowledgment, error correction, segmentation, reassembly, and sequencing.
Application Layer (Layer 7)
This layer is responsible for network applications (like HTTP or FTP) and their production of data to be transferred over the network.
Network Interface Card (NIC) {Physical Layer}
-The interface on a computer or other device that connects to the LAN
-Designed to take the communication off the physical cable or wireless signal and present it to the computer for processing
-Each NIC has a unique physical address known as a MAC address
Bridge (Data Link Layer)
-Connects two or more networks
-Forwards data to next network
-Not widely used in modern networks
Repeater (Physical Layer)
Amplifies that signal it receives so that it can travel a longer distance
Unshielded Twisted Pair (UTP)
These cables are created when pairs of wires are tested around each other to protect and cancel out interference from each other and outside sources.
Fiber-Optic Cable
Cables that use light guided through thin glass tubes instead of electrical signals to transmit data. It is very fast, but also expensive.
Single-mode Fiber
Has several thin glass strands (in rare cases, plastic) covered protective insulation. Single-mode cables have thin 10-micron strands and support a narrow range of wavelengths and higher bandwidth, making them ideal for submarine cabling across continents.
Multi-mode Fiber
Much cheaper than single mode across shorter distances. The fiber in these cables is thicker, from 50to 100 microns, Because of their thickness, they can run a wider frequency of light over shorter distances, from a couple of thousand meters to a couples of miles.
Coaxial Cable
A single copper wire surrounded by layers of plastic insulation and sheathing is used mainly in cable internet service.
Ping Command
-Tools for testing connectivity to other hosts
-Sends internet control message protocol (ICMP) to a host and listens for the reply
-Replies displays tie it took and time to live (TTL)
Traceroute/Tracert Command
-Trace the route an IP packet takes to its destination
-Displays each hop (next route) with its IP address and the time it takes to receive the packet
-Traceroute is Linux command (can only be used by super user)
-Traceroute is windows command
Tracepath command
-Similar to traceroute/tracert
-Display the path taken by packet to its destination
-Used in Linux (any user can use)
IpConfig
-Provides the user with the IP, subnet mask, and default gateway for each network adapter
-With/all can display MAC address, DHCP status and lease information
-Used in windows
-IfConfig
-Similar to IpConfig
-Used to configure the network interface
-Used in Linux
ARP
-Address Resolution Protocol
-Displays the MAC address mapping for the hosts that have been discovered in the ARP cache
Netstat
-Displays information about active ports and their state
-Useful for troubleshooting
nslookup
-Displays information for display DNS information
-used for troubleshooting DNS problems
-Displays names to ip address mappings
-Primarily used in windows
Dig
-Used to query the DNS name servers
-Helpful in troubleshooting DNS problems
-Replaced nslookup in Linux OS
Who is
-Used to lookup who owns a domain or block of IP address
-Included: name, email address and physical address
-Can purchase privacy to hide this information
-Primarily used on Linux
Route
-Used to display the current route tables on a hot
-Can be used to add or remove routes
SCP
-Secure Copy Protection
-Used to copy files between servers
-Uses SSH for authentication and encryption
FTP
-File Transfer Protocol
-Copies files from one host to another host
-Data is unencrypted; for encryption, use FTPS, which utilizes SSL/TLS)
-Uses TCP for reliability
-Used often on WAN’s and the internet
TFTP (Trivial File Transfer Protocol)
-Transfers a file from a client to a server or from server to a client
-Uses UDP
-Used on reliable (Local) network
Finger
-Displays information about a user or users on a remote system
-Includes last log-in and username
-Primarily used in Linux
Nmap (Network Mapper)
-Scans networks for hosts and open ports
-Used to determine what is deployed on a network
-Not native to either Linux or Windows
TCP Dump
-Displays TCP/IP packets and other network packets that are being transmitted over the network
-Used a packet sniffer
-Displays in readable format for troubleshooting
-Not native to either Linux or Windows
Telnet/SSH
-Both used to manage accounts and devices remotely
-SSH is encrypted
-Telnet is unencrypted
Personal Area Network (PAN)
-A network that is created to center around a person and their devices
-Communication over connections such as bluetooth or USB
Local Area Network (LAN)
-Consists of computers connected within a limited area, such as a house, lab, or office building
-LAN’s use Ethernet, Wi-Fi, or a combination of both.
Wireless Local Area Network (WLAN)
-A LAN with all devices connected wirelessly
-Users ad devices can be placed anywhere and moved anywhere in the coverage area
-Easy and inexpensive to install
Campus Area Network (CAN)
-Provides networking of multiple LAN’s across a limited area
-Each single building would typically have its own LAN
-Typically, connects LANs owned by a single company university, government, agency, etc.
Metropolitan Area Network (MAN)
-Provides networking across a larger area, such as a whole city
-Made up as many organizations within a city
Wide Area Network (WAN)
-Covers a large geographical area within its network
-WAN networks can span cities, countries, or the entire globe
-The internet is an example of WAN
Storage Area Network (SAN)
-A network that allows access to storage devices instead of general network purposes
-SANs are dedicated to storage devices and the servers that need access to them
-Allows servers to access tape libraries and disk array like they are locally attacked devices
Bus Topology
-All the devices are connected to a shared single cable
-Bus topologies are uncommon today
-Computers in a bus topology physically tap into the network cable using special adapters
-The ends of the cables have terminators
-In a bus topology only one computer can communicate at a time
-All traffic transmitted is received by everyone
Ring Topology
-The computers are connected to form a closed loop
-The computers are connected in a single line
-Each computer on the ring has an input port and an output port
-More reliable than a bus topology but communication still falls if the ring is broken
-A dual-ring topology provides high availability
Star Topology
-Also known as a hub-and-spoke network
-Composed of a central network device, such as a switch or hub
-Each device is individually connected to the central network device
-Star topologies are the most common type found in LANs
Mesh Topology
-Full mesh: Every mode of connection to all other nodes
-Partial mesh: Each node connects to a few other nodes
-Typically used for requirements of high availability and redundancy
-The most expensive and most complex topology