UNIT : 3 Basics of Network Security, Internet connection & Sharing

Security methods

 Encryption :  

Data encryption software effectively enhances data security by using an algorithm (called a cipher) and an encryption key to turn normal text into encrypted ciphertext. To an unauthorized person, the cipher data will be unreadable. That data can then be decrypted only by a user with an authorized key. Encryption is used to protect the data that you store (called data at rest) and data exchanged between databases, mobile devices, and the cloud (called data in transit). Your encryption keys must be securely managed, including protecting your critical management systems, managing a secure, off-site encryption backup, and restricting access.

 'Cryptography' : 

 Definition: Cryptography is associated with the process of converting ordinary plain text into unintelligible text and vice-versa. It is a method of storing and transmitting data in a particular form so that only those for whom it is intended can read and process it. 

 Three types of cryptographic techniques used in general. 

 . Symmetric-key cryptography 

 2. Hash functions. 

 3. Public-key cryptography 

 Authentication : 

 Authentication, along with authorization, is one of the recommended ways to boost data security and protect against data breaches. Authentication technology verifies if a user’s credentials match those stored in your database. Today’s standard authentication processes include using a combination of ways to identify an authorized user, such as passwords, PINS, security tokens, a swipe card, or biometrics. Authentication is made easier through single sign-on technology, which, with one security token, allows an authenticated user access to multiple systems, platforms, and applications. Authorization technology determines what an authenticated user are allowed to do or see on your website or server. 

 CIA (Confidentiality, Integrity, and Availability) Model : 

 The CIA (Confidentiality, Integrity, and Availability) triad is a well-known model for security policy development. The model consists of these three concepts: 

 Confidentiality – ensures that sensitive information are accessed only by an authorized person and kept away from those not authorized to possess them. It is implemented using security mechanisms such as usernames, passwords, access control lists (ACLs), and encryption. It is also common for information to be categorized according to the extent of damage that could be done should it fall into unintended hands. Security measures can then be implemented accordingly. 

 Integrity – ensures that information are in a format that is true and correct to its original purposes. The receiver of the information must have the information the creator intended him to have. The information can be edited by authorized persons only and remains in its original state when at rest. Integrity is implemented using security mechanism such as data encryption and hashing. Note that the changes in data might also occur as a result of non-human-caused events such as an electromagnetic pulse (EMP) or server crash, so it’s important to have the backup procedure and redundant systems in place to ensure data integrity. 

 Availability – ensures that information and resources are available to those who need them. It is implemented using methods such as hardware maintenance, software patching and network optimization. Processes such as redundancy, failover, RAID and high-availability clusters are used to mitigate serious consequences when hardware issues do occur. Dedicated hardware devices can be used to guard against downtime and unreachable data due to malicious actions such as distributed denial-of-service (DDoS) attacks. 

 Technology related internet: 

 Dial up tech:

 Definition - What does Dial-Up Connection mean? A dial-up connection uses a standard phone line and analog modem to access the Internet at data transfer rates (DTR) of up to 56 Kbps. A dial-up connection is the least expensive way to access the Internet, but it also slowest connection. A dial-up connection is established when two or more communication devices use a public switched telephone network (PSTN) to connect to an Internet service provider (ISP). Many remote areas depend on Internet dial-up connections because broadband and cable are rare in remote areas with low population numbers. ISPs often provide free dial-up connections, a viable alternative for budget-conscious subscribers. 

ISDN: Definition - 

What does Integrated Services Digital Network (ISDN) mean?

 Integrated Services Digital Network (ISDN) is a set of communication standards for digital telephone connection and the transmission of voice and data over a digital line. These digital lines are commonly telephone lines and exchanges established by the government. Before ISDN, it was not possible for ordinary telephone lines to provide fast transportation over a single line. ISDN was designed to run on digital telephone systems that were already in place. As such, it meets telecom's digital voice network specifications. However, it took so long for ISDN to be standardized that it was never fully deployed in the telecommunications networks it was intended for. SDN takes all kinds of data over a single telephone line at the same time. As such, voice and data are no longer separated as they were in earlier technologies, which used separate lines for different services. 

ISDN is a circuit-switched telephone network system, but it also allows access to packet-switched networks. ISDN is also used with specific protocols, such as Q.931, where it acts as the network, data link and physical layers in the OSI model. Therefore, in broad terms, ISDN is actually a suite of transmission services on the first, second and third layers of the OSI model. 

 Lease line tech: 

 Definition - What does Leased Line mean? A leased line is a dedicated communication channel that interconnects two or more sites. This is a service contract between a customer and a provider. It acts as a dedicated tunnel from one point to the other where data can continuously flow for a fixed monthly fee or rent, hence the name. Leased lines are used for Internet, data and even telephone services. They are typically run on fiber optic cables to provide large bandwidth and speed. A leased line is not really a dedicated physical connection, but a reserved circuit between two designated points that is open at all times. This is unlike traditional telephone services, which reuse the same circuit through switching. They are typically rented by large companies to connect two or more sites that need constant fast connection. These lines are leased by large telecommunication companies and are generally quite expensive. The alternative to this is to use the public switched networks while using security protocols, or to install and maintain their very own private lines, which can be more expensive.