8.1.1 Threats in networks - network security services

The idea behind setting up networks is sharing information. This sharing tends to take place through complex systems with many users, often with no clear boundaries (e.g. the Internet). Users can be hard to locate and identify, and access to local resources can originate from a host far away, through unknown paths [PFL97, p.394].

In short, threats can be grouped into the following categories:

• Wiretapping
  interception of traffic in transit;
• Impersonation
  unallowed access to systems or data by taking someone else's identity;
• Message confidentiality violation
  privacy breaches;
• Message integrity violation
  changing contents of messages, deleting messages, inserting messages, repeating messages;
• Hacking
  running programs at other hosts, using processing power at other hosts, using other hosts to perform attacks;
• Denial of service
  preventing authorized access to systems, disrupting service.

Security safeguards are called security services. One can identify 5 fundamental network security services [FOR94, p.22]:

• Authentication
• Access control
• Confidentiality
• Data integrity
• Non-repudiation