IT

• Proxy server

  A middleman or an interface between Internet user and the Internet

  
• Proxy server

  • Isolates and protects users and the internal network from the malicious stuff in Internet
  • Provides a high level of privacy
  • Functions as a firewall and do web filter
  • Provides shared network connections
  • Caches data to speed up common requests

  
• How a proxy server works

  1. User sends web request

  2. Request goes to the proxy server first

  3. Proxy server makes web request on behalf of user

  4. Proxy server collects the responses from the web server

  5. Proxy server forwards the web data to the user

  
• Advantages of using a proxy server

  • Control internet usage
  • Bandwidth savings
  • Improved speeds
  • Privacy benefits
  • Improved security
  • Access blocked resources
• Risks of using free proxy servers
• Types of proxy servers

  • Transparent proxy
  • Forward proxy
  • Reverse proxy
  • Anonymous proxy
  • Distorting proxy
  • High Anonymity proxy
  • SSL proxy

  
• Proxy server vs VPN

  VPNs provide better protection against hackers because they encrypt all traffic
• When to choose VPN or proxy
• DNS stands for Domain Name Service (or Domain Name System) and Domain Name Servers

  
• Purpose of DNS

  • Maintains a mapping of domain names with the IP address of servers
  • Translates domain names to IP addresses so browsers can load Internet resources

  
• Need for DNS
• Origin of DNS
• and if a new one does enter into the network then the change will have to be done at the server and not on the client's machine
• DNS

  Domain Name System - a system that translates domain names into IP addresses

  
• DNS traces its origins to ARPANET
• Alphabetic hostnames were introduced shortly after ARPANET's inception to allow users greater functionality, since the numeric addresses proved difficult to remember
• Originally, every site connected to ARPANET maintained a file called 'HOSTS.TXT' which contained the mapping information for all of the numeric addresses used there

  
• There were many problems that arose from the HOSTS.TXT file setup, including errors and inefficiency in making changes
• During the 1980s, a plan was laid out in RFCs 881, 882, and 883 to define what has developed into DNS
• DNS


  Organizes groups of computers into domains in a hierarchical structure
• Levels in the DNS hierarchy

  • Domain root
  • Top-level domain
  • Second-level domain
  • Subdomain
  • Host or resource

  
• Types of top-level domains

  • Generic or organization based (e.g. com, edu, gov, mil, net, org, int, aero, museum, etc)
  • Geographical or country based (e.g. in, us, au, etc)
  • Inverse (e.g. arpa)

  
• DNS is a system of distributed servers that store DNS database (IP address to domain name mappings) in a hierarchical tree structure

  
• Building blocks of DNS

  • Domain Name Space
  • Recursive Resolvers
  • Root servers
  • TLD name servers
  • Authoritative name server
  • Resource records
  • DNS clients

  
• Recursive resolver

  Acts as a middleman between a client and a DNS name server, caching information to resolve future queries
• Root name servers

  Authoritative name servers that serve the DNS root zone, directing recursive resolvers to TLD name servers

  
• TLD name servers


  Maintain information for all domain names that share a common domain extension (e.g. .com, .net)

  
• Authoritative name servers


  Contain information specific to the domain name they serve and can provide the IP address

  
• Non-authoritative name servers

  Relay information from other name servers, not considered authoritative for the domain
• Resource Records (RRs)


  Store and map domain names to the type of resources stored within a domain

  
• Common types of DNS records

  • Type 'A' record (holds IPv4 address)
  • Type 'AAAA' record (holds IPv6 address)
• DNS client


  Local computer configured to receive DNS services from a DNS server, using a resolver to query DNS servers
• DNS server plays a very important role in network, to resolve the IP request for a particular URL

  
• The DNS server basically stores the bindings between a URL and the IP of the server where the website is working
• In the age of Information Revolution, the management of information and its security is the key concern for all organizations and nations
• Networks and Information are subject to various types of attacks, and various products are available in the market for securing the systems
• The anonymity enjoyed by today's cyber attackers poses a grave threat to the global information society, the progress of an information based international economy, and the advancement of global collaboration and cooperation in all areas of human endeavor
• Home computers are typically not very secure and are easy to break-in, and when combined with high-speed Internet connections that are always turned on, intruders can quickly find and then attack home computers
• Cyber-attacks are increasingly sophisticated, with attackers using an ever-expanding variety of tactics including social engineering, malware and ransomware
• Cyber security is a critical, board-level issue, with new regulations and reporting requirements making cyber security risk oversight a challenge