In Partial Fulfillment in Professional Ethics:

Firewalls:

Firewalls can come in the form of hardware or software. Without getting into the complex details of how firewalls work, suffice it to say that function with a set of filters that are constantly monitoring traffic on the network. Whenever a packet of information triggers one of the filters, the firewall prevents it from passing through in the attempt to prevent damage. Of course, firewalls sometimes block wanted traffic, and through a continual process of refinement, the filters can be customized to improve their efficacy.

First generation: packet filters

The first paper published on firewall technology was in 1988, when engineers from Digital Equipment Corporation (DEC) developed filter systems known as packet filter firewalls. This fairly basic system was the first generation of what became a highly evolved and technical internet security feature. At AT&T Bell Labs, Bill Cheswick and Steve Bellovin were continuing their research in packet filtering and developed a working model for their own company based on their original first generation architecture.

Packet filters act by inspecting the "packets" which represent the basic unit of data transfer between computers on the Internet. If a packet matches the packet filter's set of rules, the packet filter will drop (silently discard) the packet, or reject it (discard it, and send "error responses" to the source).

This type of packet filtering pays no attention to whether a packet is part of an existing stream of traffic (i.e. it stores no information on connection "state"). Instead, it filters each packet based only on information contained in the packet itself (most commonly using a combination of the packet's source and destination address, its protocol, and, for TCP and UDP traffic, the port number).

Second generation: application layer

The key benefit of application layer filtering is that it can "understand" certain applications and protocols (such as File Transfer Protocol,DNS, or web browsing), and it can detect if an unwanted protocol is sneaking through on a non-standard port or if a protocol is being abused in any harmful way.

An application firewall is much more secure and reliable compared to packet filter firewalls because it works on all seven layers of theOSI model, from the application down to the physical Layer. This is similar to a packet filter firewall but here we can also filter information on the basis of content. Good examples of application firewalls are MS-ISA (Internet Security and Acceleration) server, McAfee Firewall Enterprise & Palo Alto PS Series firewalls. An application firewall can filter higher-layer protocols such as FTP, Telnet, DNS, DHCP, HTTP, TCP, UDP and TFTP (GSS). For example, if an organization wants to block all the information related to "foo" then content filtering can be enabled on the firewall to block that particular word. Software-based firewalls (MS-ISA) are much slower than hardware based stateful firewalls but dedicated appliances (McAfee & Palo Alto) provide much higher performance levels for Application Inspection.

Third generation: "stateful" filters

Third-generation firewalls, in addition to what first- and second-generation look for, regard placement of each individual packet within the packet series. This technology is generally referred to as a stateful packet inspection as it maintains records of all connections passing through the firewall and is able to determine whether a packet is the start of a new connection, a part of an existing connection, or is aninvalid packet. Though there is still a set of static rules in such a firewall, the state of a connection can itself be one of the criteria which trigger specific rules.

This type of firewall can actually be exploited by certain Denial-of-service attacks which can fill the connection tables with illegitimate connections.

Sources:
 http://www.wisegeek.com/what-are-firewalls.htm;
http://en.wikipedia.org/wiki/Firewall_(networking)

In Partial Fulfillment in Professional Ethics:

Encryption:

Encryption refers to algorithmic schemes that encode plain text into non-readable form or cyphertext, providing privacy. The receiver of the encrypted text uses a "key" to decrypt the message, returning it to its original plain text form. The key is the trigger mechanism to the algorithm.

Until the advent of the Internet, encryption was rarely used by the public, but was largely a military tool. Today, with online marketing, banking, healthcare and other services, even the average householder is aware of encryption.

Web browsers will encrypt text automatically when connected to a secure server, evidenced by an address beginning with https. The server decrypts the text upon its arrival, but as the information travels between computers, interception of the transmission will not be fruitful to anyone "listening in." They would only see unreadable gibberish.

There are many types of encryption and not all of it is reliable. The same computer power that yeilds strong encryption can be used to break weak encryption schemes. Initially, 64-bit encryption was thought to be quite strong, but today 128-bit encryption is the standard, and this will undoubtedly change again in the future.

Encryption can also be applied to an entire volume or drive. To use the drive, it is "mounted" using a special decryption key. In this state the drive can be used and read normally. When finished, the drive is dismounted and returns to an encrypted state, unreadable by interlopers, Trojan horses, spyware or snoops. Some people choose to keep financial programs or other sensitive data on encrypted drives.

Encryption schemes are categorized as being symmetric or asymmetric. Symmetric key algorithms such as Blowfish, AES and DES, work with a single, prearranged key that is shared between sender and receiver. This key both encrypts and decrypts text. In asymmetric encryption schemes, such as RSA and Diffie-Hellman, the scheme creates a "key pair" for the user: a public key and a private key. The public key can be published online for senders to use to encrypt text that will be sent to the owner of the public key. Once encrypted, the cyphertext cannot be decrypted except by the one who holds the private key of that key pair. This algorithm is based around the two keys working in conjunction with each other. Asymmetric encryption is considered one step more secure than symmetric encryption, because the decryption key can be kept private.

Source: http://www.wisegeek.com/what-is-encryption.htm

Law, Ethics, Computer Technology

LAW:

Law is a system of rules and guidelines, usually enforced through a set of institutions. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus ticket to trading on derivatives markets. Property law defines rights and obligations related to the transfer and title of personal and real property. Trust law applies to assets held for investment and financial security, while tort law allows claims for compensation if a person's rights or property are harmed. If the harm is criminalized in a statute, criminal law offers means by which the state can prosecute the perpetrator. Constitutional law provides a framework for the creation of law, the protection of human rights and the election of political representatives. Administrative law is used to review the decisions of government agencies, while international law governs affairs between sovereign states in activities ranging from trade to environmental regulation or military action.

ETHICS:

Ethics, also known as moral philosophy, is a branch of philosophy that addresses questions about morality—that is, concepts such as good and evil, right and wrong, virtue and vice, justice, etc.

http://en.wikipedia.org/wiki/Law