Date post: | 20-Dec-2015 |
Category: |
Documents |
View: | 219 times |
Download: | 0 times |
1
Some TCP/IP Basics
....NFSDNSTELNET SMTPFTP
UDPTCP
IP and ICMP
Ethernet, serial line, ..etc.
Application Layer
Transport Layer
Network Layer
Low-level& Physical Layer
24
Ports
Each connection initiating from or arriving at the application layer is given a logical number, the so-called port numberA TCP or UDP connection is defined by:
Source IP address,Destination IP address,Sources port number, andDestination port number.
25
Firewalls and Their Components
To the Internet
Host 1Host 2
Packet Filter-ing Router
Allowed traffic
Blocked Traffic
27
A Firewall Example
Internet
Host 1 Host 2
ApplicationGateway running
Web and FTPproxies
Packet Filter