User's Manual

Virtual Private Networking
89
N600 Wireless Dual Band Gigabit ADSL2+ Modem Router DGND3700
• Will either endpoint use fully qualified domain names (FQDNs)? FQDNs supplied by
Dynamic DNS providers (see Use a Fully Qualified Domain Name (FQDN) on page 163)
can a
llow 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 the following table)
- The typical automated Internet Key Exchange (IKE) setup (see Use Auto Policy to
Con
figure
VPN Tunnels on page 112)
- A manual keying se
tup in which you have to specify each phase of the connection
(see Use Manual Policy to Configure VPN Tunnels on page
119)
Table 16. 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 authentica
tion will you use?
- MDS. 128 bit
s, 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
90.
- See Set Up a Gateway-to-Gateway VPN Configuration on page 10
1.
• When the VPN Wizard and its VPNC defaults (see Tab
le 16 on page 89) are not
appropriate for your special circumstances, but you want to automate the Internet Key
Exchange (IKE) setup, see Use Auto Policy to Configure
VPN Tunnels on page 112.