networks

Created by: jacksie
Created on: 16-03-20 11:22

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Networks
- LANS and WANS
  - LAN
    - small geographical area
      - ethernet
      - wireless
    - school
  - wan
    - hire infrastructure
    - connect lans
    - wide geographical area
    - internet
    - fibre optic
      - copper
      - sattelites
  - factors
    - bandwidth
      - mbps
      - amount of bandwidth shared
        heavy use
    - choivce of cable
      - wireless signal weak
- hardware
  - nic
    - network interface card
      - internal hardware allows a computer to connect
      - part of the motherboard
  - switch
    - allows computer to connect to a LAN
      - sends data back to MAC adresds
  - router
    - central to packet switching
      - directs traffic
  - cables
    - cat5e/6
      - twisted pairs of four cables
        stops interference
    - coaxial
      - sinngle copper wire
        metal shiedl stops interference
    - fibre optics
      - light as a way to transmit data
        high performance
        expensive
- wireless networks
  - need a WAP
    - wireless access point
    - can use a dongle if not
      - usb and hdmi
  - bands
    - Wifif has two bands
      - 2.4ghz
        greater range
        
        get through solid objects better
      - 5 ghz
        faster transmission
        
        more non-overlapping channels
        less interference
    - split into channels
      - stop overlapping
- network types
  - client server
    - this has a central management
      - needs it specialist
      - quite expensive hardware
      - heavily dependant on server
      - central storage
        easier o back up
      - easier to add nodes
    - provides acces levels
      - more secure
  - peer to peer
    - all computers equal
      - Untitled
- topologies
  - bus and ring
    - bus has many data collisions
      - data travels in both directions
    - ring only one computer can have access
  - star
    - central switch
      - no data collisions
        and transmit data at once
      - if server or switch fails, network fails
    - very expensive hardware for 50 terminals
    - easy to add new terminal
  - mesh
    - decentralised network
    - no single point where the network fails
    - all nodes connectd
      - directly
      - indirectly in partial
    - duplicate data can occur easier
      - makes backing up data harder
    - vry expensive in a wired network
    - wireless networks now
- network protocols
  - set of rules for how networks communicate
    - mac address communicate on same network
      - assigned an unique identifier
        permanent
        
        64 bit
        usually converted into hex
      - usually used on ethernet protocols
  - ip adress communicate between different
    - ip addresses usually used for tcp/ip
      - ip adresses not linked to hardware
        static or dynamic
        large companies buy static ip
        so its easier to navigate to find their website
        
        isps have dynamic ip, more economical
        
        signed when you log on to a network
  - packets
    - data is transmitted by being broken up into packets
      - each packet has a header
        envelope
        destination
        source adress
        
        packet number
        
        payload
        data
        
        checksum number
        check if its corrupted
    - switching
      - once its been split up
        sent
        a router reads the header sends to the destination
        based on ip rules
        sends most efficient way
        numerous journeys
        makes it efficient
        
        routinely checks hasn't lost a packet
        sends a timeout
        
        checks checksum at the end
        then sorts packets to their packet number
        sends reciept to source
  - tcp/ip
    - how data is communicated between networks
    - to protocols
      - transmission control
        splits data into packets assigns packet number
        
        internet protocl
        resposnible for packet switching
      - several protocols build upon it
        http, https
        turns data into websites
        
        smtp
        sending emails
        
        ftp
        file transfer
        access file from client computer
        
        imap and pop 3
        difference is map delete email from server when you delete it
        
        pop3 deletes when downloaded
    - layers
      - protocol similar purpose
      - self contained
      - application
        https
        
        transfer/transport
        splits data into packets
        
        network
        communicates between networks
        
        link layer
        converts it to a physical network
        electrical bits
  - internet
    - domain name server
      - used for url
        converts ipadress to somethingmore memorable
    - cloud
      - hosting
        uses a server to store other files
        
        internet
      - acts like an extension to
        client server
      - pros
        no expensive hardware
        easy to increase storage
        
        data not damaged if a fire happens
        
        software updated automatically
        
        no need to pay IT staff
        
        cons
        third party, who has ownership
        
        vulnerable to hackers
        
        subscription fee
        
        need internet access
  - virtual networks
    - partition bandwidthof physical network
      - entirely software based
    - has its own firewall
    - more secure
      - need to se certain software or have access to use
        people could be on the same physical network
    - vpn
      - used to communicate securely
        over a very large network
        like internet or other wans
        
        bank
    - virtual lan
      - split lan into different lans on same hardware
- network attacks
  - passive attack
    - monitors a network
      - intercepts any sensitive data
        that they find
    - hard to detect
    - packet sniffers
    - encryptionis best defence
  - active attacks
    - actively tries to intercept data
      - easier to detect
    - best defnse is a firefall
  - brute force attacks
    - trial and improvement
      - thousandsof passwords
    - strong passwordsor locking accounts
  - insider attacks
    - someone within the network exploits data
    - user access levels
  - Denial of service
    - hacker floods website with useless data
      - Untitled
- network policy
  - penetration testing
    - siulates a potential attack
      - results reported back
    - fix possible weaknesses
  - passwords
    - prevent unauthorised access
      - 3 try
        prevent bruteforce attack
      - long combination of different charachters
  - user access levels
    - less people have access to sensitive data
    - helps prevents insider attacks
  - anti-malware software
    - help discover and destroy malware
    - isolate viruses and destroy them
    - firewall
      - check all data enrering
      - Untitled
  - encryption
    - encrypt data
    - need the correct key
    - hacker would intercept cipher text
  - network forensics
    - capturing packets
      - can review packets from an attak
      - see the weaknesses
malware
- actions
  - ransomware
    - locking files
    - require payment to open up
  - scareware
    - been infected by a load of viruses
      - follow malicious links
      - payments to fix problrms
  - open backdoors
    - future attacks
  - spyware,
    - monitoringthe keys presse by a user
  - rootkits
    - alter the permission allowing adminsterative level
  - delet or modify files
- Networks
  - LANS and WANS
    - LAN
      - small geographical area
        ethernet
        
        wireless
      - school
    - wan
      - hire infrastructure
      - connect lans
      - wide geographical area
      - internet
      - fibre optic
        copper
        
        sattelites
    - factors
      - bandwidth
        mbps
        
        amount of bandwidth shared
        heavy use
      - choivce of cable
        wireless signal weak
  - hardware
    - nic
      - network interface card
        internal hardware allows a computer to connect
        
        part of the motherboard
    - switch
      - allows computer to connect to a LAN
        sends data back to MAC adresds
    - router
      - central to packet switching
        directs traffic
    - cables
      - cat5e/6
        twisted pairs of four cables
        stops interference
      - coaxial
        sinngle copper wire
        metal shiedl stops interference
      - fibre optics
        light as a way to transmit data
        high performance
        expensive
  - wireless networks
    - need a WAP
      - wireless access point
      - can use a dongle if not
        usb and hdmi
    - bands
      - Wifif has two bands
        2.4ghz
        greater range
        
        get through solid objects better
        
        5 ghz
        faster transmission
        
        more non-overlapping channels
        less interference
      - split into channels
        stop overlapping
  - network types
    - client server
      - this has a central management
        needs it specialist
        
        quite expensive hardware
        
        heavily dependant on server
        
        central storage
        easier o back up
        
        easier to add nodes
      - provides acces levels
        more secure
    - peer to peer
      - all computers equal
        Untitled
  - topologies
    - bus and ring
      - bus has many data collisions
        data travels in both directions
      - ring only one computer can have access
    - star
      - central switch
        no data collisions
        and transmit data at once
        
        if server or switch fails, network fails
      - very expensive hardware for 50 terminals
      - easy to add new terminal
    - mesh
      - decentralised network
      - no single point where the network fails
      - all nodes connectd
        directly
        
        indirectly in partial
      - duplicate data can occur easier
        makes backing up data harder
      - vry expensive in a wired network
      - wireless networks now
  - network protocols
    - set of rules for how networks communicate
      - mac address communicate on same network
        assigned an unique identifier
        permanent
        
        64 bit
        usually converted into hex
        
        usually used on ethernet protocols
    - ip adress communicate between different
      - ip addresses usually used for tcp/ip
        ip adresses not linked to hardware
        static or dynamic
        large companies buy static ip
        so its easier to navigate to find their website
        
        isps have dynamic ip, more economical
        
        signed when you log on to a network
    - packets
      - data is transmitted by being broken up into packets
        each packet has a header
        envelope
        destination
        source adress
        
        packet number
        
        payload
        data
        
        checksum number
        check if its corrupted
      - switching
        once its been split up
        sent
        a router reads the header sends to the destination
        based on ip rules
        sends most efficient way
        numerous journeys
        makes it efficient
        
        routinely checks hasn't lost a packet
        sends a timeout
        
        checks checksum at the end
        then sorts packets to their packet number
        sends reciept to source
    - tcp/ip
      - how data is communicated between networks
      - to protocols
        transmission control
        splits data into packets assigns packet number
        
        internet protocl
        resposnible for packet switching
        
        several protocols build upon it
        http, https
        turns data into websites
        
        smtp
        sending emails
        
        ftp
        file transfer
        access file from client computer
        
        imap and pop 3
        difference is map delete email from server when you delete it
        
        pop3 deletes when downloaded
      - layers
        protocol similar purpose
        
        self contained
        
        application
        https
        
        transfer/transport
        splits data into packets
        
        network
        communicates between networks
        
        link layer
        converts it to a physical network
        electrical bits
    - internet
      - domain name server
        used for url
        converts ipadress to somethingmore memorable
      - cloud
        hosting
        uses a server to store other files
        
        internet
        
        acts like an extension to
        client server
        
        pros
        no expensive hardware
        easy to increase storage
        
        data not damaged if a fire happens
        
        software updated automatically
        
        no need to pay IT staff
        
        cons
        third party, who has ownership
        
        vulnerable to hackers
        
        subscription fee
        
        need internet access
    - virtual networks
      - partition bandwidthof physical network
        entirely software based
      - has its own firewall
      - more secure
        need to se certain software or have access to use
        people could be on the same physical network
      - vpn
        used to communicate securely
        over a very large network
        like internet or other wans
        
        bank
      - virtual lan
        split lan into different lans on same hardware
  - network attacks
    - passive attack
      - monitors a network
        intercepts any sensitive data
        that they find
      - hard to detect
      - packet sniffers
      - encryptionis best defence
    - active attacks
      - actively tries to intercept data
        easier to detect
      - best defnse is a firefall
    - brute force attacks
      - trial and improvement
        thousandsof passwords
      - strong passwordsor locking accounts
    - insider attacks
      - someone within the network exploits data
      - user access levels
    - Denial of service
      - hacker floods website with useless data
        Untitled
  - network policy
    - penetration testing
      - siulates a potential attack
        results reported back
      - fix possible weaknesses
    - passwords
      - prevent unauthorised access
        3 try
        prevent bruteforce attack
        
        long combination of different charachters
    - user access levels
      - less people have access to sensitive data
      - helps prevents insider attacks
    - anti-malware software
      - help discover and destroy malware
      - isolate viruses and destroy them
      - firewall
        check all data enrering
        
        Untitled
    - encryption
      - encrypt data
      - need the correct key
      - hacker would intercept cipher text
    - network forensics
      - capturing packets
        can review packets from an attak
        
        see the weaknesses
- types of malware
  - viruses
    - atach themselves to .exe files
      - replicate very quickly
        activated by user opening file
  - worms
    - similar to viruses
      - replicate very quickly
    - no user help
  - trojans
    - software which looks good but is malware

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