1. VPN Concepts
   1. Virtual Private Network
   2. Types
      1. Client
         1. VPN Client
         2. Cisco VPN Client
         3. Cisco AnyConnect
      2. Site-to-Site
   3. Encryption
      1. Encryption Key
         1. Key Pair
         2. Shared Key
   4. Protocols
      1. IPsec
         1. Internet Protocol Security
      2. SSL/TLS
         1. Secure Sockets Layer
         2. Transport Layer Security
2. GRE
   1. Generic Routing Encapsulation
   2. GRE Tunnel
   3. Tunnel Interface
3. PPPoE
   1. PPP over Ethernet
   2. Virtual-Access Interface
   3. PPPoE Session
   4. Dialer Interface
   5. Dial Pool
4. DMVPN
   1. Dynamic Multipoint VPN
   2. NHRP
      1. Next-Hop Resolution Protocol
         1. NHRP Client
         2. NHRP Server