Session hijacking refers to the exploitation of a valid computer session to gain unauthorized access to information or services in a computer system. In particular, it is used to refer to the theft of a magic cookie used to authenticate a user to a remote server. It has particular relevance to Web developers, as the HTTP cookies used to maintain a session on many Web sites can be easily stolen by an attacker using an intermediary computer or with access to the saved cookies on the victim's computer (see HTTP cookie theft).TCP session hijacking is when a hacker takes over a TCP session between two machines. Since most authentication only occurs at the start of a TCP session, this allows the hacker to gain access to a machine. Answer option A is incorrect. Spoofing is a technique that makes a transmission appear to have come from an authentic source by forging the IP address, email address, caller ID, etc. In IP spoofing, a hacker modifies packet headers by using someone else's IP address to hide his identity. However, spoofing cannot be used while surfing the Internet, chatting on-line, etc. because forging the source IP address causes the responses to be misdirected. Answer option B is incorrect. Smurf is an attack that generates significant computer network traffic on a victim network. This is a type of denial-of-service attack that floods a target system via spoofed broadcast ping messages. In such attacks, a perpetrator sends a large amount of ICMP echo request (ping) traffic to IP broadcast addresses, all of which have a spoofed source IP address of the intended victim. If the routing device delivering traffic to those broadcast addresses delivers the IP broadcast to all hosts, most hosts on that IP network will take the ICMP echo request and reply to it with an echo reply, which multiplies the traffic by the number of hosts responding. Answer option D is incorrect. Phishing is a type of scam that entices a user to disclose personal information such as social security number, bank account details, or credit card number. An example of phishing attack is a fraudulent e-mail that appears to come from a user's bank asking to change his online banking password. When the user clicks the link available on the e-mail, it directs him to a phishing site which replicates the original bank site. The phishing site lures the user to provide his personal information.

Client-server networking is also known as client-server computing. It is a distributed application architecture
that partitions tasks or workloads between service providers (servers) and service requesters, called clients.
Often clients and servers operate over a computer network on separate hardware. A server machine is a high-
performance host that is running one or more server programs which share its resources with clients. A client
does not share any of its resources, but requests a server's content or service function. Clients therefore
initiate
communication sessions with servers which await (listen to) incoming requests.
Answer options D and B are incorrect. Peer-to-peer (P2P) computing or networking is a distributed application
architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent
participants in the application. They are said to form a peer-to-peer network of nodes. Peer-to-peer networking
(also known simply as peer networking) differs from client-server networking, where certain devices have the
responsibility to provide or "serve" data, and other devices consume or otherwise act as "clients" of those
servers.

Email tracking
Explanation:
Email tracking is a method for monitoring the e-mail delivery to the intended recipient. Most tracking technologies utilize some form of digitally time-stamped record to reveal the exact time and date at which e-mail was received or opened, as well the IP address of the recipient. When a user uses such tools to send an e-mail, forward an e-mail, reply to an e-mail, or modify an e-mail, the resulting actions and tracks of the original e-mail are logged. The sender is notified of all actions performed on the tracked e-mail by an automatically generated e-mail. eMailTracker Pro and MailTracking.com are the tools that can be used to perform email tracking.

Adeona is a free laptop tracker that helps in tracking a user's laptop in case it gets stolen. All it takes is to install the Adeona software client on the user's laptop, pick a password, and make it run in the background. If at one point, the user's laptop gets stolen and is connected to the Internet, the Adeona software sends the criminal's IP address. Using the Adeona Recovery, the IP address can then be retrieved. Knowing the IP address helps in tracking the geographical location of the stolen device. Answer option D is incorrect. Nessus is proprietary comprehensive vulnerability scanning software. It is free of charge for personal use in a non-enterprise environment. Its goal is to detect potential vulnerabilities on tested systems. It is capable of checking various types of vulnerabilities, some of which are as follows:Vulnerabilities that allow a remote cracker to control or access sensitive data on a system Misconfiguration (e.g. open mail relay, missing patches, etc)Default passwords, a few common passwords, and blank/absent passwords on some system accounts. Nessus can also call Hydra (an external tool) to launch a dictionary attack.Denials of service against the TCP/IP stack by using mangled packets Answer option A is incorrect. SAINT stands for System Administrator's Integrated Network Tool. It is computer software used for scanning computer networks for security vulnerabilities, and exploiting found vulnerabilities. The SAINT scanner screens every live system on a network for TCP and UDP services. For each service it finds running, it launches a set of probes designed to detect anything that could allow an attacker to gain unauthorized access, create a denial-ofservice, or gain sensitive information about the network. Answer option C is incorrect. Snort is an open source network intrusion detection system. The Snort application analyzes network traffic in realtime mode. It performs packet sniffing, packet logging, protocol analysis, and a content search to detect a variety of potential attacks.