1 Some TCP/IP Basics....NFSDNSTELNETSMTPFTP UDPTCP IP and ICMP Ethernet, serial line,..etc. Application Layer Transport Layer Network Layer Low-level & Physical Layer
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24 Ports Each connection initiating from or arriving at the application layer is given a logical number, the so-called port number A TCP or UDP connection is defined by: Source IP address, Destination IP address, Sources port number, and Destination port number.
25 Firewalls and Their Components To the Internet Host 1Host 2 Packet Filter- ing Router Allowed traffic Blocked Traffic
26 Firewalls and Their Components Web request Host 1Host 2 Application Gateway With Web proxy
27 A Firewall Example Internet Host 1Host 2 Application Gateway running Web and FTP proxies Packet Filter
28 firewall Actual Traffic?
29 Assignment 0: