1. Virtual Private Networks
By: Jacob Anderson

2. What is a Virtual Private network?
A secure network connection on top of a wider network
Hence virtual
Uses a larger network, like the internet, to connect a remote site and users together
Taking advantage of availability
Mimics a physical network
Convenient accessibility
Better alternative to a leased line

4. leased lines Pay a provider for a “symmetric telecommunications” line
Monthly price
Each side of the cable is permanently connected
No telephone number
Advantage in speed
Normally fiber optic
Dedicated
Most of the time infeasible

5. VPN vs. SSH SSH works at the application layer
Port specific
SSH establishes connections on a one-to-one basis
A single client to a server or another single entity
A VPN can connect a user to a whole network
Great for business off-site extension
A VPN is not limited to single-port connections
Network layer connectivity

6. VPN with SSH
In some cases, security may be necessary within the local network as well
Confidential data that only some employees are eligible to view
VPN handles the security over the internet
Encapsulates SSH protocol packet
SSH, then, provides application to application security within
Only sending and receiving employees will be able to view

7. How a VPN works An IP packet is wrapped in an extra layer
Which provides security
The extra layer is processed by a router
Not at a higher level in the OSI protocol stack

8. VPN Router
VPN is accomplished using a specific type of router and/or VPN software
Designed to handle the IP layer security protocol
Cost for a small business VPN router is between 150 to 400 dollars
This one is $150

9. VPN Protocols
PPTP
L2TP
L2F
IPSEC
Most commonly used

10. IPSEC Consists of two main protocol sets: Authentication Header (AH)
Encapsulating Security Payload (ESP)

11. Authentication Header
Known as “Tunnel Mode”
Replay bit
Triggered when viewed (Know whether compromised)
Process:
1) IP header and data payload is hashed
2) Hash is used to build a new header, which is appended
3) New packet is transmitted to the VPN router
4) The receiving router hashes the IP header and data payload as well, and the result must match the previously appended hash (the authentication header)

12. AH Diagram

13. Encapsulating Security Payload (ESP)
Known as “Transport Mode”
Provides source authentication, integrity, an anti-replay service, and limited traffic flow confidentiality
Encryption of the IP Packet Layer is performed
Standard is 56-bit DES
But others can be used

14. ESP Diagram

15. When to use each mode Between IPSec Gateways
End station to IPSec Gateway
IPSec router to server
End station to end station

16. Advantages of VPN Cost Security Scalability
Increase infrastructure without physical addition
Compatibility with broadband
Multi-point communication
Business communication links
LAN to LAN
Mobile workers access to LAN
Off-site remote work more possible

17. References http://en.wikipedia.org/wiki/Virtual_private_netw ork
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