Prof. Michael P. Harris, CCNA, CCAI
Director, Cisco Networking Academy
Computer Science Department
Computer Security Overview
Network Security policies
An organization's information is one of its most valuable assets. Network security
is becoming increasingly important as networks become larger and more
complex. Today's mobile and telecommuting users require access locally as well
as from outside the network. Threats to an organization's resources can come
from internal as well as external sources. Information theft and destruction as
well as resource access denial are real concerns for users and system
administrators. The overall goal of any information security system is to ensure
that information is accurate and available where and when needed. There are a
number of components that must interact in a comprehensive network security
policy.
Physical Access Security - The first line of defense locally to protect network
equipment such as servers, switches, and routers is to keep them in a locked,
climate controlled, and fire protected environment. If equipment is not physically
accessible to unauthorized personnel, there is less chance of accidental or
intentional tampering.
Login / Password Security - Login and password security policy require that
any user accessing a workstation or server have a valid login ID and password.
Windows NT, Windows 2000, Windows XP, Novell Netware, and UNIX all have
specific requirements for creating and changing passwords. The system
administrator can also require that passwords be changed periodically. Setting
screen savers that time out and activate your workstation lock are additional
measures that enhance login security.
File Systems Security - A major component in any comprehensive security
policy, file system security determines who can get to what data and what they
can do with it. System administrators set up file system security based on users,
groups, and permissions.
Virus protection - Viruses can do tremendous damage to individual
workstations and network servers. Many network operating systems and
workstations require anti-virus software for adequate protection. UNIX is
susceptible to virus attacks like other operating systems, but most viruses are
written for Windows based systems because the viruses can affect more systems
faster. In addition, most virus creators are not familiar with the UNIX environment
enough to know how to create a "UNIX" virus.
Remote Access Security - With increases in telecommuting, the network must
allow legitimate users to access resources remotely while protecting them from
unauthorized access. Access servers and software provide this function.
Internet Firewalls - Organizations that maintain Internet web sites need
protection from hackers. Various software and hardware solutions are available
to help ensure that web servers are available to provide services to legitimate
users.
Data backups - A comprehensive security policy must include regular backups
of important data to minimize downtime in the event of a security breach or
disaster such as fire or flood. Backup media such as tapes should be kept offsite
in a climate controlled secure environment. Test restores of data should be
performed periodically to ensure that data can be recovered from the backups.
Disaster Recovery Plan - A written plan is needed that identifies critical data
and documents by functional department within an organization. It describes
protective measures and steps necessary to ensure that the organization can
continue to operate and get back to business quickly with minimum impact to
customers.
Audits - Security audits should be performed periodically to ensure that the
organization and its users are following the security policy and preparing
adequately for disaster recovery. Security Audit tools are also available for
system administrators to analyze and detect security loopholes such as files with
open permissions.
Summary:
The primary function of system security is to deny access to unauthorized users.
Keeping computer information secure is important to the user and the system
administrator. By protecting their files and accounts from unauthorized use, users
are also protecting their job and reputation. Standard security features include:
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user passwords that restrict access to the system
file and directory protection with permissions
files that control remote logins and commands on individual workstations
other features that enable system administrators to check for security
breaches.
QUIZ:
http://www.delmar.edu/Courses/seminar/security_policy.html
(Drag and drop the correct answers beside the matching descriptions.)