48
VPN
Introduction to IPSec
This chapter introduces IPSec, the method, or rather set of methods used to provide VPN
functionality. IPSec, Internet Protocol Security, is a set of protocols defined by the IETF,
Internet Engineering Task Force, to provide IP security at the network layer.
An IPSec based VPN, such as that of the DFL-700, is made up of two basic parts:
•
Internet Key Exchange security protocol (IKE)
•
IPSec
protocol
(ESP)
The first part, IKE, is the initial negotiation phase, where the two VPN endpoints agree on
which methods will be used to provide security for the underlying IP traffic. Furthermore, IKE
is used to manage connections, by defining a set of Security Associations (SA), for each
connection. Each SA is unidirectional, so there will be at least two SA per IPSec connection.
The other part is the actual IP data being transferred, using the encryption and authentication
methods agreed upon in the IKE negotiation. This can be accomplished in a number of ways;
by using the IPSec protocol ESP.
To set up an IPSec Virtual Private Network (VPN), you do not need to configure an
Access Policy to enable encryption. Just fill in the following settings: VPN Name, Source
Subnet (Local Net), Destination Gateway (If LAN-to-LAN), Destination Subnet (If LAN-to-LAN),
and Authentication Method (Pre-shared key or Certificate). The firewalls on both ends must
use the same Pre-shared key or set of Certificates and IPSec lifetime to make a VPN
connection.
Introduction to PPTP
PPTP, Point-to-Point Tunneling Protocol, jointly developed by Microsoft, US Robotics,
and various other remote access companies known collectively as the PPTP Forum, is used
to provide IP security at the network layer.
A PPTP based VPN is made up by these parts:
•
Point-to-Point Protocol (PPP)
•
Authentication Protocols (PAP, CHAP, MS-CHAP v1, MS-CHAP v2)
•
Microsoft Point-To-Point Encryption (MPPE)
•
Generic Routing Encapsulation (GRE)
PPTP uses TCP port 1723 for it's control connection and uses GRE (IP protocol 47) for
the PPP data. PPTP supports data encryption by using MPPE.
Summary of Contents for DFL-700 - Security Appliance
Page 1: ...D Link DFL 700 Network Security Firewall Manual Building Networks for People 04 18 2005 TM ...
Page 102: ...102 5 Select Connect to the network at my workplace and click Next ...
Page 103: ...6 Select Virtual Private Network connection and click Next ...
Page 104: ...104 7 Name the connection MainOffice and click Next ...
Page 105: ...8 Select Do not dial the initial connection and click Next ...
Page 106: ...106 9 Type the IP address to the server 194 0 2 20 and click Next 10 Click Finish ...
