VPN – Virtual Private Network

1. What is a VPN?
   • It is a logical connection between two entities typically secure over an unsecure channel.
   • Virtual – Private network traffic transported over ‘public’ network
   • A sort of tunneling is created to achieve that.
   • Private – Traffic is isolated and optionally encrypted.
2. Why do we need VPNs?
   • Cost savings
   • Compatible with any transport technology (traffic issues)
   • Security
   • In earlier 1980s they mainly focused on providing services not on security.
   • After some attacks, they came to know that security is the essential thing for shared medium.
3. Eavesdropping attack:
   • Eavesdropping is the unauthorized real-time interception of a private communication, such as a phone call, instant message, and videoconference or fax transmission.
   • The term eavesdrop derives from the practice of actually standing under the eaves of a house, listening to conversations inside.
   • The attacker is going to access the content of the packet (Man in the middle attack) using Wireshark, SPAN, RSPAN…etc.
4. Masquerading attack:
   • A masquerade attack is an attack that uses a fake identity, such as a network identity to gain unauthorized access to personal computer information through legitimate access identification.
   • If an authorization process is not fully protected, it can become extremely vulnerable to a masquerade attack.
   • In this attack, the attacker is going to hide his own identity and pretend to become someone else
5. Phishing attack:
   • Phishing is a type of social engineering attack often used to steal user data, including login credentials and credit card numbers.
   • It occurs when an attacker, masquerading as a trusted entity, dupes a victim into opening an email, instant message, or text message.
   • The recipient is then tricked into clicking a malicious link, which can lead to the revealing of sensitive information.
   • Now it is not allowed.
6. VPN Examples:
   1. VLAN
   2. Frame-relay PVC (via DLCI)
   3. MPLS VPN (layer2/layer3)
   4. AToM
   5. GRE
   6. IPsec
   7. SSL
   8. MACsec
7. What are the types of VPN?
   1. Site to Site VPN (supported by Router & ASA)
      • Between two VPN gateways (router-router/firewall-firewall)
      • Statically or dynamically assigned IPv4/IPv6 addresses
      • IPsec is the framework used to secure data
        • IKEv1 or IKEv2 are used to dynamically negotiate the tunnel
      • Some vendors, not Cisco also offer SSL VPN
   2. Remote VPN (Router & ASA)
      • Between a VPN gateway and an end-user/device
      • VPN gateway has a static IPv4/IPv6 address
      • End-user has a dynamic IPv4/IPv6 address in general
      • Client-based
        • IPsec (IKEv1 or IKEv2) and SSL VPN (TSLv1 or SSLv3)
      • Clientless, browser-based
        • SSL VPN only (TLSv1 or SSLv3)
   3. DMVPN (Router)
   4. GETVPN (Router)
   5. FIEX VPN (Router & ASA)
   6. SSL VPN (Router & ASA)
8. Features of VPN:
   1. Confidentiality
   2. Integrity
   3. Authentication
   4. Anti-replay
9. Confidentiality:
   • It can be achieved only by CIPHER.
   • CIPHER: It is used to convert the plain text traffic into unreadable format.
   • CIPHER types:
     1. Stream CIPHER: Bit by Bit encryption
        • This is very CPU intensive work, so it is not supported by Cisco
        • This method can be used for highly secure communication. (Military, Navy)
        • Suppose we has to send 10 bits data then it runs the algorithm 10 times for encryption & 10 times for decryption, total 20 times.