The internet - Internet security Flashcards
Explain what the key exchange problem is, in relation to a symmetric cipher
- How to pass the key (from the sender) to the receiver;
- Without it being intercepted / securely;
Explain what it means for a cipher to be described as being computationally secure
The cipher cannot be cracked, by any known method in a polynomial amount of time
what is a TCP/IP protocol
a stack set of protocols used in turn, to format a message so it can be sent over a network
- each layer provides a specific function within the transmission of the message
layers of the TCP/IP
- application layer
- transport layer
- network layer
- link layer
summarise the application layer
- established the protocols for the transmission
- enabling communication over the network
- Uses protocols like HTTP, SMTP, FTP, and DNS to handle specific communication tasks,
- : Ensures that data is delivered to the correct application on the destination device through port numbers
summarise the transport layer
- establishes an end to end connection
- performs error detection/correction
- uses port number to pass the data on to the correct software in the application layer
- add port number
- split data up into segments
- performs flow control
-manages congestion
what does TCP/IP stand for
transmission control protocol/internet protocol
summarise the network layer
- adds the IP addresses of the source and destination
- Performs routing
- selects the next host/ hop to transmit a packet to
- performs error detection on the packet header
- the addition of an IP and port forms a socket, which specifies the device the packet must be sent to
summarise the link layer
- handles communication between devices on the same local network.
- adds the mac address, identifying the NICs
- Ensures data is transmitted over physical hardware like Ethernet or Wi-Fi.
- MAC addresses change with each hop
how is data received after tcp/ip
- link layer removes mac address from each packet
- passes it to network layer
- network layer removes IP address from each packet, passes it to transport layer
- transport layer removes removes the port number from each packet, reassembles the packet in the correct order
- passes it to app layer
- app layer presents the image data for the user in a brpwser
features of a mac address
uniquely identifies a physical device with an NIC (NETWORK INTERFACE CARD)
- may be the destination computer or a router
-packets move around the lower layers of the stack as they hop across routers, changing their mac address as they go
what are well known ports
why are they used
-A reserved port number that has a specific purpose
- Used because the communication is initiated by the sender, therefore the port number must be the same for all initial email communications
20 = file transfer protocol
80 and 8080 = HTTP
443 = HTTPS(encrypted HTTP)
25 = SMTP (simple mail transfer protocol)
what is a port
- a virtual endpoint used to identify specific processes or services/applications in network communication.
examples of malicious software/ malware
- worms
- viruses
- trojans
summarise worms
- sub class of a virus
- standalone software that can replicate itself without user intervention
summarise viruses
- rely on other host files to be opened in order to spread themselves
- most become memory resident when their host file is executed
- once the virus is in memory, any other uninfected file that runs, becomes infected when copied into memory
where do other common viruses reside
macro files usually attached to word processing and spreadsheet data files
difference between a worm and a virus
viruses rely on other host files(usually executable programs) to be opened in order to spread themselves, whereas worms do not
how does a worm enter a computer
through vulnerability or by tricking the user into opening a file, often an attachment
virus or worm
ILOVEYOU bug - worm
Melissa - virus
blaster - worm
summarise a trojan
- manifests itself in a useful file, game, or utility you wanna install
- when installed, the payload is released,without irritation
- cannot self replicate
- serve to open up back doors in your computer to the Internet, so that the processing power, Internet bandwidth and data can be exploited remotely
what do malware do
- exploits vulnerabilities in systems
what is phishing
using email to manipulate a victim into visiting a fake website and giving away personal info
methods that protect against malware
- guarding against buffer overflow attack
- guarding against SQL injection attack
- use of strong passwords for login credentials
- two factor authentication
- use of access rights
- spamming filtering
- regular operating system and antivirus updates