Transcript Network Technology Foundations

Network Technology
Foundations
© 2004 ProsoftTraining
All Rights Reserved
Lesson 5:
Network Security and
IT Career Opportunities
Objectives











Define security
Identify various kinds of network attacks
Describe computer viruses
Describe authentication principles
Explain the three major types of encryption
Describe network security protocols and
technologies
Describe firewalls, security zones and common
firewall topologies
Describe security audit principles
Describe the function of a UPS
Review career opportunities in the IT industry
Describe the importance of successfully explaining
technical issues to non-technical audiences
Defining Security


Security — a set of procedures designed to
protect transmitted and stored information,
as well as network resources
Security administrators must determine
which people can take appropriate actions
on specific items at the appropriate time
Overview of
Network Attack Types





Spoofing
Man in the middle
DOS
Distributed DDOS
Brute force





Dictionary
Back door
Buffer overflow
Trojan horse
Social
engineering
• To avoid attacks:
• Install stable updates
• Use encryption
• Be suspicious of information requests
• Remain informed
Viruses and Worms



Virus — code that causes damage to systems
Virus types
• Macro/script
• File infecting
• Boot sector
• Stealth
• Polymorphic
• Retro
Worm — similar to virus but automatically
replicates
Defeating Attacks


OSI/RM security services
• Authentication
• Access control
• Data confidentiality
• Data integrity
• Non-repudiation
Updates
Authentication




Three authentication methods
• What you know
• What you have
• Who you are
Passwords
• Strong passwords
• Age passwords appropriately
Account lockout — disables accounts after a
given number of invalid passwords have been
entered
Account reset — enables you to choose
whether accounts reset automatically after a
given interval
Encryption



The primary means to ensure privacy across the
enterprise
Symmetric-key encryption
• One key to encrypt and decrypt
• All parties must know and trust one another
Symmetric algorithms:
• DES
• Triple DES
• AES
Encryption (cont’d)


Asymmetric-key encryption
• Uses a key pair (one public, one private)
• Used to create a digital signature
Asymmetric algorithms
• RSA
• DSA
Encryption (cont’d)


Hash encryption
• Uses a hash table that contains a hash function
• Used for information that will not be decrypted
or read
Hash algorithms
• MD2, MD4 and MD5
• SHA
Encryption (cont’d)


PGP — uses a combination of the three
encryption types
For example:
• Use symmetric-key encryption to scramble the
original message you want to send
• Use asymmetric-key encryption to encrypt only
the symmetric key you just used
• Use hash encryption to "sign" the message and
ensure that no one can tamper with it
Virtual Private Network (VPN)




A technique that allows secure communication
across long distances, usually for a company
extranet
In a VPN, the Internet is often the corporate
network backbone
Appropriate for any organization requiring secure
external access to internal resources
All VPNs are tunneling protocols — encryption
occurs at the source and decryption occurs at the
destination
Virtual Private Network (VPN)
(cont’d)

VPN protocols
• PPTP — works only with IP protocols
• L2TP — works with non-IP protocols
• IPsec — more flexible than PPTP or L2TP
because you can specify different
authentication methods
Remote Access Server (RAS)


Requires the use of dial-up modems to dial
up, connect and log on to RAS
Offers security through a callback feature:
• A user logs on to RAS
• The user is disconnected
• RAS calls the user back to ensure the call
was made from an authorized computer
Digital Certificates





Provide authoritative identification
Verify the sender's identity
Use the X.509 standard
Are used for non-repudiation
Contain digital signatures
• CA
Public Key Infrastructure (PKI)


PKI CA servers:
• Are repositories for managing digital
certificates
• Enable the secure creation and management of
digital certificates
• Provide the ability to revoke an invalid key
If you need a certificate for a server, use PKI
Firewall


A secure computer system placed between a
trusted network and an untrusted one, such as
the Internet
• The most common location for a firewall is
between a corporate LAN and the Internet
Allows users from a protected network to access
a public network while simultaneously making the
protected company's products and services
available to the public
Internal and
Personal Firewalls


Internal firewall — resides inside your
company's internal network
• Internal firewalls can:
 Protect sensitive systems
 Isolate networks that still need
Internet connectivity but that use
software that may cause problems
with other company resources
Personal firewall — offers protection for an
individual system
Packet Filtering


Packet filter — inspects each packet for
predefined content
Packet filters filter data based on the following
fields in the packet:
• Source IP address
• Destination IP address
• TCP/UDP source port
• TCP/UDP destination port
Proxy Server



Replaces the network IP address with a single IP
address
Provide the following services:
• Hiding of network resources
• Logging
• Caching
Proxies come in two basic forms:
• Circuit-level gateways
• Application-level gateways
Proxy Gateways



Circuit-level gateway — acts as a proxy
between the Internet and your internal systems
Application-level gateway — same as a circuitlevel gateway but at the application level
Most firewalls are combinations of packet
filtering, circuit-level gateways and applicationlevel gateways
Network Address
Translation (NAT)


The practice of hiding internal IP addresses
from the external network
Three ways to provide NAT:
• Configure masquerading on a packetfiltering firewall
• Configure a circuit-level gateway
• Use a proxy server to conduct requests
on behalf of internal hosts
Accessing
Internet Services


If Internet access is required and a network
is located behind a proxy server or firewall,
you may have problems accessing Internet
services that use ports other than common
ports
To avoid these problems:
• Make sure the network has access to all
Internet-related protocols used by the
company
• Make sure that the IP addresses
assigned to the computers in your
network have permission to access the
Internet
Troubleshooting
Access Through Firewalls



Firewalls can cause a bottleneck
Firewalls may not allow homebased account access to the
corporate e-mail server
To troubleshoot firewall problems:
• Verify that you are using the correct
IP address and subnet mask
• Check your default gateway and
verify that the computer can
communicate with systems on the
same subnet
Security Zones




DMZ — a mini-network that resides between a
company's internal network and the external
network
Intranet — a security zone available only to
authorized organization employees
Extranet — a private network that allows
selected access to outsiders only after they
provide authentication information
VLAN — a logical grouping of hosts, generally
not implemented by a firewall
Firewall Topologies


Common firewall implementations:
• Packet filter
• Dual-homed bastion host
• Triple-homed bastion host
• Screened subnet (back-to-back firewalls)
Bastion host — a computer that houses
various firewall components and services
and is connected to a public network
Packet Filter Topology
Dual-Homed Bastion Host
Triple-Homed Bastion Host
Screened Subnet
Security Audit


Review of the state of the network
Auditing process:
• Conduct a status quo analysis
• Conduct a risk analysis
• Make recommendations concerning what was
found
Uninterruptible
Power Supply (UPS)


Device that allows a computer to keep
running temporarily when the primary
power source is lost
Can be configured to:
• Shut down entire systems automatically
• Shut down only certain components
automatically
• Place components into minimal power
use mode until the system is shut down
manually
IT Industry
Career Opportunities






Web site designer
Web application
developer
Web architect
Web site analyst
Web site manager
Database
administrator






Server
administrator
Network engineer
Security manager
Security
analyst/consultant
PC repair
technician
Help desk
technician
Conducting Job Searches











Participating in on-campus interviews
Searching through want ads
Visiting employment agencies/employment
placement services
Attending job/career fairs
Volunteering
Seeking part-time work
Networking (socially)
Working with an executive search firm
Mailing cover letters and résumés to companies
Applying in person
Entering résumés electronically or posting them
to the Web
Using the Internet
to Conduct Job Searches


Use Usenet job newsgroups and search
engines, such as:
• groups.google.com
• hotjobs.yahoo.com
• careers.excite.com
• www.monster.com
Enter keywords to narrow your search to
specific job types, and retrieve available job
listings that relate to your career goals
Creating a Résumé



Formatting a résumé:
• Create using a word-processing program
• Use formatting to increase visual appeal
• Recipient needs same word-processing
program to be able to read résumés
Text format résumés:
• Contain little formatting
• Intended for keyword-searchable résumé
databases and applicant tracking systems
RTF résumés:
• Incorporate basic formatting techniques
• Can be read by many different programs on
Creating a Résumé (cont’d)


PDF résumés:
• Compatible across all computer platforms
• Not vulnerable to viruses
• Need PDF software
HTML résumés:
• Posted as Web pages
• Retain the formatting characteristics of a
word-processing file
Education and IT Careers


University degrees are available in:
• Computer science
• Computer engineering
• Management information systems
Employers are also looking for:
• Interpersonal skills
• Business skills
• Project management skills
Education and IT Careers (cont’d)


Importance of continuing education
Obtain certifications in:
• A+
• CIW
• Network+
• Security+ Certification
Technical Concepts
and Training






Communicating technical issues to end
users
Justifying IT-related expenses to
management
Understanding problems and concerns of
end users
Providing understandable solutions
Remembering the ROI affect of IT decisions
Presenting technical data clearly so that
managers understand the information and
can make informed decisions