CTP 204CTP 2042006-2007 FALL2006-2007 FALL

FirewallsFirewallsFiltering PropertiesFiltering PropertiesAnti-virus ProgramsAnti-virus Programs

WHAT IS A FIREWALL?WHAT IS A FIREWALL?

System or system groupSystem or system group Traffic conrollerTraffic conroller

FIREWALLS PROPERTIESFIREWALLS PROPERTIES

Contol the trafficContol the traffic1.1. Let the traffic goLet the traffic go2.2. Stop the trafficStop the traffic

Block the packetsBlock the packets Provide a first line of defenseProvide a first line of defense Make public network secureMake public network secure Can not block viruses(disadvantage)Can not block viruses(disadvantage) Block unauthorized accessBlock unauthorized access

How does a firewall work?How does a firewall work?

Create a guide tableCreate a guide table Checks the packetsChecks the packets

PACKET(Source IP,Sink IP,Source Port,Sink Port)PACKET(Source IP,Sink IP,Source Port,Sink Port)

Compare them with firewall rulesCompare them with firewall rules Delete or checks guide tableDelete or checks guide table

PERSONAL FIREWALLSPERSONAL FIREWALLS

Without a firewall:Without a firewall: Ftp(optional)Ftp(optional) Http(optional)Http(optional) SmtpSmtp Pop3Pop3

PERSONAL SECURITYPERSONAL SECURITY

Update the applications run on Internet Update the applications run on Internet (Outlook,Internet Explorer, ICQ,MSN…)(Outlook,Internet Explorer, ICQ,MSN…)

Usa a firewall and close unused ports Usa a firewall and close unused ports (IPTABLES for Linux, NETFILTER for Windows)(IPTABLES for Linux, NETFILTER for Windows)

Use a anti-virus program & always updateUse a anti-virus program & always update Disable Java, Java Script, ActiveX choiceDisable Java, Java Script, ActiveX choice Do not open the e-mails before searching for Do not open the e-mails before searching for

virusvirus Always take back-up of important filesAlways take back-up of important files Create a boot disc for hard-disc failureCreate a boot disc for hard-disc failure

FIREWALL TYPESFIREWALL TYPES

Software based Hardware basedSoftware based Hardware based

FILTERING PROPERTIESFILTERING PROPERTIES1.1. Packet FilteringPacket Filtering

Check only source IP&port, sink IP&portCheck only source IP&port, sink IP&port Do not follow sessionDo not follow session

2.2. Stateful InspectionStateful Inspection Check the packet flow characteristic for each sessionCheck the packet flow characteristic for each session Complex from other filtering but secureComplex from other filtering but secure

3.3. NAT(Network Address Translation)NAT(Network Address Translation) Session levelSession level Block the IP address of the computersBlock the IP address of the computers Show nat address & use only one IPShow nat address & use only one IP

4.4. ProxyProxy Application levelApplication level Filter ftp,telnet applicationsFilter ftp,telnet applications Filter certain commands of an applicationFilter certain commands of an application Watch or block the local network users connectionWatch or block the local network users connection High level securityHigh level security

NAT MECANISMNAT MECANISM

STEPS OF HOW DOES THE STEPS OF HOW DOES THE MECANISM WORKSMECANISM WORKS

1.1. Take the packet from local networkTake the packet from local network2.2. Hold IP and port info of this packetHold IP and port info of this packet3.3. Make the source address self-addressMake the source address self-address4.4. Send packet to out worldSend packet to out world5.5. Take the answer packet from out worldTake the answer packet from out world6.6. Check the tables and find the owner of the Check the tables and find the owner of the

packetpacket

COMPARING NAT & PROXYCOMPARING NAT & PROXY

Both hides IP addresses of the computersBoth hides IP addresses of the computers Both can be used when IP address not enoughBoth can be used when IP address not enough Both install session(Only Proxy interfere content)Both install session(Only Proxy interfere content) Both slow down the network(CPU-RAM)Both slow down the network(CPU-RAM)

NAT easier to set up NAT easier to set up Proxy Proxy require settings for each client require settings for each client (Internet (Internet

Explorer,ICQ,MSN…)Explorer,ICQ,MSN…)

Both are secureBoth are secure

FIREWALLS PERFORMANCEFIREWALLS PERFORMANCE

Related with network performanceRelated with network performance RAM and CPU should be higher when RAM and CPU should be higher when

NAT & PROXY installedNAT & PROXY installed Operation system should be harmony with Operation system should be harmony with

firewallfirewall

INSTALLING FIREWALLSINSTALLING FIREWALLS

1.1. CENTERAL buildingCENTERAL building

2.2. MIXED buildingMIXED building

CENTRAL BuildingCENTRAL Building

CENTRAL BuildingCENTRAL Building

AdvantagesAdvantages Easy to configEasy to config SecurerSecurer

DisadvantagesDisadvantages Effect all segmentsEffect all segments Difficult to back upDifficult to back up Difficult to upgrade according to each userDifficult to upgrade according to each user

MIXED BuildingMIXED Building

MIXED BuildingMIXED Building

AdvantagesAdvantages Effect only one segmentEffect only one segment Easy back-upEasy back-up Used many different functionsUsed many different functions

DisadvantagesDisadvantages Expensive than central buildingExpensive than central building Can not generalize security politicsCan not generalize security politics

VLAN(VIRTUAL LAN)VLAN(VIRTUAL LAN)

•Seperate each group

•Makes the network securer

•Supply more security with firewall

FIREWALL SETTINGSFIREWALL SETTINGS

1.1. Direct connection to firewall:Direct connection to firewall: Enter the rules to command line(console)Enter the rules to command line(console)

2.2. If has web surface:If has web surface: Enter the rules on web serverEnter the rules on web server

3.3. Installing the firewall setting console to Installing the firewall setting console to another (secure)pc:another (secure)pc:

Enter the rules on that (secure)pcEnter the rules on that (secure)pc

WINDOWS FIREWALLWINDOWS FIREWALL

WINDOWS FIREWALLWINDOWS FIREWALL

Dangerous to open a new port for an unknown application

WINDOWS FIREWALLWINDOWS FIREWALL

ANTI-VIRUS PROGRAMSANTI-VIRUS PROGRAMS

COMMON PROPERTIESCOMMON PROPERTIES ExecutableExecutable ClonableClonable HideableHideable Change a program codesChange a program codes Change itselfChange itself

VIRUS TYPESVIRUS TYPES

1.1. File VirusFile Virus2.2. Command Runnable VirusCommand Runnable Virus3.3. Boot Sector VirusBoot Sector Virus4.4. Script VirusScript Virus5.5. MacroMacro6.6. WormWorm7.7. TrojanTrojan8.8. DailerDailer

File VirusFile Virus

Finishes with .com .bat .exeFinishes with .com .bat .exe Change fileChange file Delete fileDelete file

Command Runnable VirusCommand Runnable Virus

Roll the O\S filesRoll the O\S files Target command.comTarget command.com

Boot Sector VirusBoot Sector Virus

Place to MBR(Master Boot Record)Place to MBR(Master Boot Record) Run before O\SRun before O\S

Script VirusScript Virus

Roll from Internet Explorer,Outlook…Roll from Internet Explorer,Outlook… Active when a web site or e-mail openedActive when a web site or e-mail opened

MacroMacro

Use macro functions of MS-OfficeUse macro functions of MS-Office Roll while openingRoll while opening

WormWorm

Roll using IP address & opened share filesRoll using IP address & opened share files Use RPC(Remote Procedure Call) of Use RPC(Remote Procedure Call) of

WINDOWSWINDOWS Roll to sharing filesRoll to sharing files Copy it-selfCopy it-self Block the Internet trafficBlock the Internet traffic

TrojanTrojan

Take the passwords of victim PCTake the passwords of victim PC Spy virusSpy virus No damageNo damage

DailerDailer

Effect dial-up usersEffect dial-up users Disconnect the user from InternetDisconnect the user from Internet Mute the modemMute the modem Connect to an operator abroadConnect to an operator abroad Make user pay too much moneyMake user pay too much money

ANTI-VIRUS PROGRAM PROPERTIESANTI-VIRUS PROGRAM PROPERTIES

Check existing foldersCheck existing folders Clean\Quarantine contagious virusClean\Quarantine contagious virus Block the virus from CD,disc,internetBlock the virus from CD,disc,internet

How does a anti-virus program work?How does a anti-virus program work?

Create a databaseCreate a database Update the databaseUpdate the database Take the control of the computerTake the control of the computer Check all imports to pcCheck all imports to pc

COMPARING ANTI-VIRUS COMPARING ANTI-VIRUS PROGRAMSPROGRAMS

http://anti-http://anti-virusvirus--softwaresoftware--reviewreview..toptenreviewstoptenreviews

.com/?ttreng=1&ttrkey=anti-virus+program.com/?ttreng=1&ttrkey=anti-virus+programss