Download ppt - Chapter 11 Security, Backup and User Training 11.1 Security Threats Security ThreatsSecurity Threats 11.2 Backup and Restore Backup and RestoreBackup and

Chapter 11 Security, Chapter 11 Security, Backup and User TrainingBackup and User Training

11.1 Security Threats11.1 Security Threats

11.2 Backup and Restore11.2 Backup and Restore

11.3 User Training and Support11.3 User Training and Support

Chapter 11 Security, backup, support

11.1 Security Threats

Consequences of poor security:Company secrets fallen into wrong hands Disclosure of personal informationInformation may be modified or destroyedNetwork cannot functionThe network becomes a center that spreads virus

Security threats External threats Internal threats

11.1.1 Against External Threats

External threats due to hackers

Methods include: Front-door attack

obtains an access rights to log on a systemcracking

• use a program to generate passwords

Backdoor attackmakes use of the bugs in NOS

Wireless attackaccessing through wireless connection



A. Against Front-door Attacks

Several ways to against front-door attacks: firewall restricting access to server dial-back




1. Firewall is a software (or, sw + hw) to prevent unauthorised access sits between

router, and network

decides messages to pass through Techniques:

packet filteringcompares the IP address of packets against a blacklist

network address translator (NAT) hides the IP addresses of computers inside a network




2. Restricting access to a server limit access to a server based on the Ethernet MAC addresses

3. Dial-back for remote access to a LAN using modem Procedures:

1. user dials the system2. user logs in3. system terminates the connection4. system dials the preprogrammed phone number



B. Against Backdoor Attacks

Backdoor attacks takes advantages of security holes

problems in NOS done by worm

a malicious programinstalls a “backdoor” to the victim system

• allow hackers to get incarries out DoS attack

• overload computational resources • consume the bandwidth

Outbreak: many networks are harmed in short period Solution: update the NOS with patches regularly



C. Against Wireless Attacks

Wireless signals travel through air easy to intercept

Protection by encryption

WEP (Wired equivalent privacy) WPA (Wi-Fi Protected Access)

Issues The encryption capability of many wireless devices is non-activated by

default. Encryption can be broken:

e.g. WEP (Wired equivalent privacy) has been broken Solution:

Activate encryption Use a strong authentication Share out resources only when needed


11.1.2 Against Internal Threats

Internal threats internal users access files that they are not supposed to

accesse.g. students access teachers’ files

caused by improper account settingusers leaving their seats without logging offusers writing down their passwords



A. Account Security

Account security means managing user accounts properly to enhance the security of a network. includes the following settings

Set up groups and assign access rightsRemove “guest” Rename the default administrative account.Set password policies Watch for incorrect password attemptsEstablish times of day for log on



B. Directory Permission

Directory permission rights assigned to users includes

create only• add new file to a directory only

• similar to a mailbox on street read only

• open a file for viewing, but cannot change the filechange

• open/edit/delete files

• but, cannot grant rights to other usersfull control



C. Against Malicious software

Malicious software developed for the purpose of doing harm to a compute

system How is a computer infected?

opening the attachment in an e-mail sharing of data files use of illegal software installing software from an unknown source attacked by hackers who spread the virus



C. Against Malicious software

Avoiding infection Install anti-virus software in each computer.

Update the virus definition file regularlyScan your hard disk to check for virus regularlyScan all downloaded files and e-mail attachments

Do not open or forward e-mails with attachments from unknown sources

Do not use illegal software. Install firewall Install latest patches for OS and application software Make sure that your computer will not boot from a floppy

disk drive or CD-ROM drive


11.2 Backup and Restore (1/3)

A. Full and Incremental backups Full backup

copies all files from a hard disk to the backup mediacan take very long time slow down the network done once every week

Incremental backupbackup only those files modified since the last full backupdone every night



B. Backup medium magnetic tape or optical disk choice based on

speed, reliability, storage duration

C. Location for storing backup copies safe location away from the network system locked physically



D. Configure the scheduled backups schedule backup after busy hours

E. Test the ability to recover from backups regularly test the ability to recover regularly

F. Document the procedures in restoration write steps in restoring from backup copies clearly

for other people to restore successfully


11.3 User Training and Support (1/4)

Training for end-users include: basic concept about a network how to trouble-shoot simple problems how to log on the system from a workstation how to access network resources how to perform daily backup importance of keeping password secret importance of security importance of avoiding virus infection



Modes of Training Orientation sessions

show users what they have and how to use it

Training sessions schedule some classroom traininginteraction

Job aids Quick reference cards, manuals, keyboard shortcuts



A. Getting support Network administrators may get support from

help menu of NOSdocumentation from the vendors hotline of the vendorsforums and newsgroups on the InternetCD-ROM/Web sites of vendors

Users should be provided with Web pages for simple troubleshootingonline documentsphone numbers for technical support



B. Types of support Out-sourced technical support services (TSS)

carrying out routine maintenance tasks• backing up files

• updating OS patches

• keeping the stocks solving emergency problems

• failure of server, router, switches, or NOS

Options: One or two technical staff may reside in the company
