ENVS 1200 Lecture Notes - Lecture 8: Packet Analyzer
13 May 2018
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ENVS 1200 Tutorial 8 Notes – Physical and Logical Access Restriction
Introduction
• There are numerous ways to intrude into a networked system.
• The tools for packet sniffing are free and readily available to anyone.
• Packet sniffing is defined as the reading of the data in a packet as it passes through a
network.
• With wired networks, packet sniffing can be achieved by physically tapping into the
network itself or by reading packets as they pass through a node.
• Hub-based netorks are partiularly ulnerale eause anyone onneted to the us
at any point can read every packet that uses the bus.
• Wireless networks are even worse.
• Anyone within range of a radio signal can receive the signal.
• In general, it is safest to assume that it is possible to intercept and read any packet
passing through a network.
• This makes passwords that travel through a network unencrypted useless at protecting
a network and its computers from intrusion.
• The Internet provides an additional means of intrusion access.
• Any system on any network that is publicly accessible from the Internet is susceptible to
probing attacks that seek IP address/port numbers combinations that will accept data
packets.
• Specially constructed packets can then be used to access and modify the host machine.
• A number of measures are used to protect systems and networks from intrusion.
• Physical eavesdropping on local area networks is minimized by limiting access to
network wiring and network equipment to personnel who are responsible for the
equipment.
• Logical access is limited with intelligent firewall design that blocks public access where it
is not required and robust network applications that drop or repel packets that might be
invasive.
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