Servers and network security (p2 revision)

Servers and network security (p2 revision)

1. Client server

   • Is managed by a server which takes requests from client devices
   • Disadvantages
     • Very expensive to set up and maintain
     • Can become overloaded when too many devices are accessing it at once
     • All devices depend on a server
   • Advantages
     • Easier to install and update software
     • Files are stored centrally
     • Easier to manage network security
     • Easier to preform backups
     • Reliability

2. Peer to Peer server

   • Devices connected together to share data with each other. All devices on the network are equal and do not depend on a server
   • Example: Home network - Access to a printer, share files between devices, access to other wireless devices (e.g. speakers)
   • Disadvantages
     • Computers slow down when other devices access them as they are not as powerful as servers
     • No Centralised Management
     • Less Reliable
     • Copying files can be duplicated - harder to know which files are up to date
   • Advantages
     • Cost
     • Easier to maintain
     • No dependence on a server

3. Network security

   • Brute-force Attack – when all possible password combinations are systematically tried, with the hope of getting it right.
     • Using strong passwords ✔ Locking accounts after a certain number of login attempts ✔ Using 2 step verification (e.g. a code sent to mobile phone to confirm identity)
   • Denial-of-Service Attack (DoS) - when a network resource becomes deliberately overloaded (‘flooded’) with unnecessary requests, preventing it from responding normally.
     • Using a firewall to control which programs can send and receive data packets, so that only authorised users & trusted programs can access the network.
   • Distributed-Denial-of-Service Attack (DDoS) – when the requests come from many sources so you cannot just block a single IP address.
   • Malware is software that has been purposely developed to damage, disrupt or take control of computer systems.
     • Running anti-malware software regularly ✔ NOT downloading software from unknown sources ✔ NOT clicking on unknown links

4. Passive Attack – data is monitored e.g. wiretap Active Attack - data is modified e.g. malware Inside Attack– by someone within the organisation Outside Attack – by an illegitimate, external user

   • Computer viruses – insert themselves in normal programs. Viruses can replicate themselves and transfer from one computer to another. They are activated by a user often as email attachments and attachment to other files and programs.