User's Manual

Virtual Private Networking
105
N300 Wireless ADSL2+ Modem Router DGN2200v4
page 148) can allow a VPN endpoint with a dynamic IP address to initiate or respond to a
tunnel request. Otherwise, the side using a dynamic IP address has to always be the
initiator
.
• Which method will you use to configure your VPN tunnels?
- The VPN Wizard using VPNC defaults (see Table 5, Parameters Recommended by
the VPNC and Used in the VPN Wizard on page 105).
- The typical automated Internet Key Exchange (IKE) setup (see Use Auto Policy to
Configure VPN Tunnels on page 124).
- A manual keying setup in which you need to specify each phase of the connection
(see Use Manual Policy to Configure VPN Tunnels on page 131)?
Table 5. Parameters Recommended by the VPNC and Used in the VPN Wizard
Parameter Factory Default Setting
Secure Association Main Mode
Authentication Method Pre-Shared Key
Encryption Method 3DES
Authentication Protocol SHA-1
Diffie-Hellman (DH) Group Group 2 (1024 bit)
Key Life 8 hours
IKE Life Time 1 hour
• What level of IPSec VPN encryption will you use?
- DES.
The Data Encryption Standard (DES) processes input data that is 64 bits wide,
encrypting these values using a 56-bit key. Faster but less secure than 3DES.
- 3DES.
Triple DES achieves a higher level of security by encrypting the data three
times using DES with three different, unrelated keys.
• What level of authentication will you use?
- MD5. 128 bits, faster but less secure.
- SHA-1. 160 bits, slower but more secure.
VPN Tunnel Configuration
There are two tunnel configurations and three ways to configure them:
• Use the VPN Wizard to configure a VPN tunnel (recommended for most situations):
- See Set Up a Client-to-Gateway VPN Configuration on page 106.
- See Set Up a Gateway-to-Gateway VPN Configuration on page 116.
• See Use Auto Policy to Configure VPN Tunnels on page 124 when the VPN Wizard and
its VPNC defaults are not appropriate for your special circumstances, but you want to
automate the Internet Key Exchange (IKE) setup.