Networks and Network Security Flashcards
Range
Maximum distance a transmission can travel before being degraded.
Server
A computer that stores files and/or provides other services to a network
Social Engineering techniques
Phishing - sending emails pretending to be from companies to get people to reveal information
Blagging - using invented scenario to engage victim in a way which makes them more likely to give up personal information
Baiting -
Promise of cash or good in return for personal information
Quid pro Quo-
Promise of service in return for personal information
Types of Malware
Virus / Worm:
Piece of code capable of copying itself
Worm can do without human intervention, virus can’t
Trojan:
Program that appears harmless but isnt
Ransomware:
Encrypting users files and then attacker demanding ransom to unencrypt them
Keyloggers:
Software that obtains info by monitoring and recording keyboard activity
Penetration Testing
White Box:
Simulates insider who has some knowledge
Black Box:
Simulates external hacker with no previous knowledge
Methods of Protecting Networks and Data
Firewalls
Access control
Physical security
Anti-malware software
Encryption
Backup
Acceptable use policies
ATIL
Application layer
- encodes/decodes the message into a form that is understood by the sender and the recipient devices using protocols like HTTP, file transfer protocol (FTP) and SMTP
Transport layer
- breaks down the message into small pieces called
packets
. Each packet is given a packet number and the total number of packets. The recipient uses this information to assemble the packets in the correct order. It also allows the recipient to see if there are any missing packets.
Internet layer
- adds the sender’s
IP address and that of the recipient. The
network then knows where to send the message, and where it came from. This is sometimes called the network layer.
Link layer
- enables the physical transfer of packets between
nodes on a network, and between one network and another.
Bus Topology
In a bus network all the nodes are joined to one cable - the bus. At each end of the cable, a terminator is fitted to stop signals reflecting back down the bus.
Advantages:
it is easy to install extra network devices
it is cheap to install as it doesn’t require much cable
Disadvantages:
if the main cable fails or gets damaged, the whole network will fail
as more nodes are connected, the performance of the network will become slower because of
data collisions
every node on the network receives all of the
data sent on the network - this is a security risk
Star Topology
In a star topology all nodes indirectly connect to each other through one or more switches or hubs
A hub broadcasts a message across the whole
network
Whereas a switch sends the message to the intended recipient only. The switch or hub acts as a central point through which all communications are passed. Star topologies are used in many networks, large and small.
Advantages:
Each node is separately connected. Therefore, the failure of one node or its link, also known as
transmission media does not affect any other nodes.
New nodes can be added to the network simply by connecting them to the switch.
Star networks tend to have higher performance, since a message is passed on only to its intended recipient.
Disadvantages:
the whole network fails if the switch fails, since no node can communicate
a wired star topology requires a lot of cable - in a large network this can be expensive
Mesh Topology
In a mesh topology there is no central connection point. Instead, each node is connected to at least one other node and usually to more than one. Each node is capable of sending messages to and receiving messages from other nodes. The nodes act as relays, passing on a message towards its final destination.
Advantages:
messages can be received more quickly if the route to the intended recipient is short
messages should always get through as they have many possible routes they can travel along
multiple connections mean - in theory - that no node should be isolated
multiple connections mean each node can transmit to and receive from more than one node at the same time
new nodes can be added without interruption or interfering with other nodes
Disadvantages:
fully connected mesh networks can be impractical to set up because of the high number of connections needed
many connections require a lot of maintenance
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