1. Kittiphan Techakittiroj
Firewall
Kittiphan Techakittiroj

2. Firewall Isolate two side of network Work on higher layer
Two main kinds:
Packet Filtering
Bastion Server

3. Packet Filtering Filter out the prohibit traffic
Firewall
Packet Filtering
Filter out the prohibit traffic
Usually on layer 3 & 4
IP number: allow & prohibit
TCP port number: allow & prohibit e.g.
#21 for FTP
#23 for telnet
#25 for (SMTP)
#80 for world wide web

4. Packet Filtering cont. Transparent for the allow service
Firewall
Packet Filtering cont.
Transparent for the allow service
Standard Configuration
dual homed: hosting two network card
screening router

5. Bastion Server Server act like a gateway
Firewall
Bastion Server
Server act like a gateway
NOT allow any packet to go through
Proxy server

6. Reference Books
Developing Secure Commerce Applications by Online O’Reilly Web Development Courses ( 1999)
Client/Server Survival Guide by Robert Orfali, Dan Harkey, Jeri Edwards (John Wiley & Sons: 1999)