3.2 Network Security Flashcards
Describe how usernames and passwords secure a network.
Each user is given a unique username. They can decide on a password which only they will know. The username and password must be entered when the user logs on to use the network. When being entered, the password is kept secret by appearing in asterisk or dot format. The software on the file server then checks that a username with the password entered exists. This stops unauthorised users from accessing the network.
Give 4 good properties of a password.
- Combination of letters, numbers and other characters
- Minimum number of characters
- Changed regularly
- Kept confidential.
Give 3 bad properties of a password.
- The same as your username, pet’s name or family name
- A word
- Written down anywhere.
Describe how levels of access work.
Each group of users has a different level of access, meaning they are limited to the amount of data they can access or the actions they can carry out. This protects the network from damage by users.
Define encryption.
A way of encoding data before transmitting it on a netwotk. Data is encoded by the sending computer using a software encoding key and sent along the communications line. The data can only be decoded by the receiving computer is it has the decodig key. This keeps data secure whilst it is being transmitted between computers.
Define virus.
A computer program which is designed to damage some aspect of an information system. They generally need to attach themselves to a document or program so that they can infect the computer. They can enter a network through the internet, by email, or from a portable storage device like a flash memory stick.
What is a worm?
A virus designed to spread by replicating itself, and does not have to be attached to any document or program. This can cause problems on a network as the worm will slow down processing whilst reproducing.
What is a Trojan horse?
A virus that gains entry to a user’s computer ‘in disguise’.The user may think it is a useful program, but instead it provides hackers with an entry point to the user’s computer.
How can virus attacks be prevented?
The computer system can install virus protection software which automatically updates itself to take account of any new viruses. It scans all of the linked computers each day to ensure there are no infections. Likewise any portable storage devices entered are scanned to ensure it is virus-free. If a virus is detected, the user and system administrator will be notified.
Define spam.
The bulk sending of electronic messages to people who have not requested it.
Define spyware.
Malicious software (malware) which is secretly installed on a user’s computer. It collects information about the user such as their visited websites. It can also allow other programs to be installed, change the computer settings, or even monitor keystrokes to capture passwords.
Describe a firewall.
A firewall can be integrated into a hardware device or software program. It filters information coming from the internet to the computer network. This prevents hackers, viruses and spam from entering the network via the internet, and users within the network from uploading data onto the internet.
Why is data backup important?
To ensure there is a copy of data that can be loaded onto the system if the original data is lost.
Describe 2 types of hard disk backup.
- Networked-Attached Storage (NAS) devices - This is a hard disk storage system which is connected to the network through a network point. It is not part of the main server. When a bacup is scheduled, all of the files from the file server are copied onto the NAS. A NAS device can share data with other servers and devices on the network.
- Direct-Attached Storage (DAS) devices - This is a hard disk storage system which is connected directly to the main computer in the network. Backups are scheduled and all the data on the sever is copied to the DAS. A DAS device cannot be accessed through other network devices.
Describe magnetic tape as a method of backup.
The tape is stored in the tape drive on the file server and a backup of the system is taken at regular intervals. Backup activity may slow the network down because it uses sytem resources, so it is usually done when the computer system is not busy, eg. during the night.
