HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Computer Networks and Security• network packet sniffers,• password attacks,• IP spoofing,• middle man attacks,• denial-of-service attacks, and• application layer attacks.Packet SniffersNetworked computers communicate serially by sending one datapiece after another. The large data pieces are broken into smaller pieces.The smaller pieces are the network packets.Some network applications distribute the network packets in cleartext. These packets are not encrypted and can be processed and read bya packet sniffer which can be implemented in either software or hardware.The packet sniffer is normally used for network fault analysis. Itcan pick the packets off the network and process them for data analysis.The packet sniffer software will capture the packets received on aphysical network wire. There are freeware and shareware packet sniffersthat allow any user to get into a system without any knowledge of theinner workings of the system.In a networked database, a packet sniffer can be used to get informationthat is queried from the database, along with user account namesand the passwords used. This can be a problem since users often reusetheir log-in names and passwords across multiple applications.Other packet sniffer information includes the topology of the network,what computers run specific services, how many computers areon the network and which computers have access to others.Password AttacksPassword attacks occur when there are repeated attempts to identifya user account or password. These attacks take place from bruteforce, repeated attempts which are often automated. Other attacks cancome from Trojan horse programs, IP spoofing, and packet sniffers.Once an attacker gains access to the network, they could modifythe routing tables for the network. Then, all network packets can be©2001 by The Fairmont Press, Inc. All rights reserved.