CS206 Final Term Preparation

CS 206 final term preparation

Here are some important lines from the provided topics:

receiving data to and from an ISP, using the same old phone line, but running at much faster speeds."

" Also, you can make phones calls and surf (send IP packets) at the same time."

"DSL allows the same old analog voice signal to be sent over the line by a phone. At the same time, DSL allows a separate digital signal to go over the same phone line."

" The DSLAM splits out the digital signal and analog signal from the local loop."

Topic 74: Sending Data without a Phone Line

" Cable Internet access makes use of the cable television company’s existing cable television infrastructure."

" Fiber optics connects the cable head end to neighborhood-level junctions, from which traditional coaxial cable is then used to reach individual houses."

" Frequency division multiplexing: different channels transmitted in different frequency bands."

Topic 75: Introduction to AAA Security Model

"AAA stands for authentication, authorization, and accounting."

" Authentication is a five-step process."

" The second 'A' in AAA is for Authorization. It refers to the process of figuring out what a particular user is allowed to do."

" The last 'A' in AAA is accounting. The same servers that perform authentication and authorization services can keep a record of each request to authenticate or authorize a user."

Topic 76: Password Authentication Protocol (PAP)

"ISPs authenticate users before they can even use the network." " Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP) are used by ISPs."

"PAP sends the username and password in clear-text."

" To protect against password theft, CHAP does not send the password as cleartext."

"CHAP uses six steps to authenticate the user."

Topic 77: Virtual Private Network (VPN)

" Encryption allows a computer to apply a mathematical formula to data."

" These days, it is common for users to encrypt data before sending it over the Internet."

"VPNs create a private network, but they do so logically, or virtually."

" For Barney to use the VPN, he must encrypt the packet as he creates it."

"A VPN device inside the corporate network is called a VPN concentrator."

Topic 78: Enterprise Network and the Internet

" When you connect an enterprise network to the Internet, one of the first things you must decide is what you want to allow to pass to and from the Internet."

" To secure Fredsco's network, two things have to be kept in mind: Between which two hosts do packets need to flow? Which host begins that communication?"

" Typical types of traffic allowed between an enterprise and the Internet."

" Traffic that is typically not allowed between an enterprise and the Internet."

Topic 79: Firewalls, Demilitarized Zone, IDS:

"A network engineer configures the firewall with a set of rules that tells it what's legal and what isn't."

" The firewall allows some packets to pass through it and discards others to enforce the rules."

" Cisco’s firewall product is called a PIX firewall."

" As a firewall watches the traffic entering the network, it knows the nature of the traffic that is allowed to flow through it."

"A host who is initiating a new flow can be recognized by looking at: The first TCP segment used to create a TCP connection SYN flag bit =1, and source IP address of the packet."

" Firewalls are like routers. They forward packets based on destination IP address."

" They have at least two physical interfaces. They can have more than two interfaces. Outside interface connects to Internet. Inside interface connects to internal network."

"A third interface connected to a LAN called a demilitarized zone (DMZ), somewhere between inside & outside interfaces."

" With a DMZ, Internet-accessible servers can be placed on a different LAN."

"A stronger firewall rule: No TCP connections can be initiated from outside to the inside. The only flows allowed are for servers in the DMZ."

" Intrusion detection systems (IDSs) watch packets that a firewall allows through."

" They look for things in the packets to determine if someone is cheating the firewall and doing bad things to servers in the network."

" Some IDS devices sit in the network, watching packets that pass over a LAN and are called network-based IDSs."

" Those IDS software that sit on the servers are called host-based IDSs."

For Topic 80: Introduction to Wireshark, here are some important lines:

" Wireshark is a network packet analyzer which captures network packets and displays that packet data as detailed as possible."

" Wireshark is a free open-source software program."