Network Security Questions And Answers | letsbug

Network Security 

1.  Answer the following questions in short.

1. What is meant by Network security?

    Answer: 

        Network / Computer security consists of the provisions and policies adopted by a network administrator to prevent and monitor unauthorized access, misuse, modification, or denial of a computer network and network-accessible resources.

        Network security involves the authorization of access to data in a network, which is controlled by the network administrator.

2. What is plaintext and ciphertext?

    Answer: 

        The plaintext or clear text message can be understood by anybody, (sender, recipients) else who gets access total message.

        When a plaintext message is codified using any suitable scheme (encryption), the resulting message is called ciphertext.

        The message to be encrypted, know as "plain text"

        The output of the encryption process, known as the "ciphertext"

3. What is attack? What are its type?

    Answer: 

        An attack is a threat that is carried out (threat action) and if successful, leads to an undesirable violation of security. 

        A network security attack refers to, an act of breaching security provisions of a network.

     Type of Attacks (A General View)

1. Criminal Attacks
2. Publicity Attacks
3. Legal Attacks

    Type of Attacks (A Technical View)

1. Interruption
2. Interception
3. Modification
4. Fabrication

    And these attacks are further grouped in to active attacks and passive attacks.

4. What is encryption and decryption?

    Answer: 

        Encryption is the process of converting the original information which is in meaningful and readable form ( in cryptography called plaintext) into unreadable form (in cryptography called ciphertext) and requires a key for this conversion.

        The process of converting the ciphertext into plaintext is called decryption. Decryption is the reverse process of encryption and also uses a key for conversion.

5. Write names of substitution techniques?

    Answer:

    Names of substitution techniques are:

• Caesar cipher
• Playfair cipher
• Mono-alphabetic cipher
• Transposition cipher        

6. What are types of Firewall?

Answer: 

    Types of firewall

1. Packet Filters Firewall: A packet-filtering router applies a set of rules to each incoming and outgoing IP packet and then forwards or discards the packet. A router is typically configured to filter packets going in both directions(from and to the internal network).
2. Stateful Inspection Firewall: Stateful packet firewalls (performs stateful packet inspection) are able to determine the connection state of packet, unlike packet filtering firewall, which makes it more efficient. It keeps track of state of networks connection travelling across it, such as TCP streams.
3. Proxy Servers: A proxy service is an application that redirects user's requests to the actual services based on an organization's security policy. All communication between a user and that actual server occurs through the proxy server.    

2.  Define the following terms:

1. Firewall 

    Answer: 

        A firewall is defined as a single choke point that keeps unauthorized users out of trusted or protected network, prohibits potential vulnerable services from entering and leaving the network and provides protection from various kinds of IP spoofing and routing attacks.

2. Steganography

    Answer: 

        Steganography is a technique that facilitates hiding of message that is to be kept secret inside other messages. It is also known as stego.

        The advantage of steganography over cryptography alone is that the intended secret message does not attract attention to itself as an object of scrutiny.

3. Copyright

    Answer: 

        Copyright refers to the legal right of the owner of intellectual property. In simpler terms, copyright is the right to copy. This means that the original creators of products and anyone they give authorization to are only ones with the exclusive right to reproduce the work.

4. Passive attack

    Answer: 

        A passive attack monitors unencrypted traffic and looks for clear-text passwords and sensitive information that can be used in other types of attacks.

        Passive attacks include traffic analysis, monitoring of unprotected communications, decrypting weakly encrypted traffic, and capturing authentication information such as passwords.

5. Active attack

    Answer: 

        In an active attack, the attacker tries to bypass or break into secured systems. This can be done through stealth, viruses, worms or Trojan horses.

        Active attacks include attempts to avoid or break protection features, to introduce malicious code, and to steal or modify information.     

3.  Answer the following questions:

1. How proxy servers and firewalls help in maintaining network security? Explain.

    Answer: 

        A firewall inserted between premises of the network connects and the Internet. This location permits the firewall to provide authentication and other security services to remote users in order to prevent unauthorized users from logging in to the network.

        A proxy service is an application that redirects user's request to the actual services based on an organization's security policy. All Communication between a user and the actual server occurs through the proxy server.

• A proxy server acts as a communications broker between client and the actual application servers. Because it acts as a checkpoint where requests are validated against specific application, a proxy server is usually processing intensive and can become a bottleneck under heavy traffic conditions.
• There are two classes of proxy servers: application gateways, which operate at the application layer: and circuit-level gateway, which operate at the transport layer.
• Application Level Gateway:
• An application gateway is a proxy server that provides access control at the application layer.
• It acts as an application-layer gateway between the protected network and the untrusted network. Because it operates at the application layer, it is able to examine traffic in detail and, therefore, is considered the most secure types of firewall.
• The user contacts the gateway using TCP/IP application, such as Telnet or FTP, and the gateway asks the user for the name of the remote host to be accessed.
• When the user responds and provides a valid user ID and authentication information, the gateway contacts the application on the remote host and relays TCP segments containing the application data between the two endpoints.
• Circuit-level Gateways:
• A circuit-level gateway is a proxy server that validates TCP and UDP sessions before allowing a connection or circuit through the firewall. It is actively involved in the connection establishment and does not allow packets to be forwarded until the necessary access control rule have satisfied.
• A circuit-level gateway does not permit an end-to-end TCP connection; rather, the gateway sets up two TCP connections, one between itself and a TCP user or an inner host and one between itself and a TCP user on an outside host.
• Once the two connections are established, the gateway typically relays, TCP segments from one connection to the other without examining the contents. The security function consist of determining which connections will be allowed.