ZyXEL Communications ZyXEL ZyWALL P1 - Manual (Page 144)

ZyWALL P1 User’s Guide
Chapter 9 VPN Screens 143
Address Type Use the drop-down list box to choose Single Address, Range Address, or
Subnet Address. Select Single Address with a single IP address. Select
Range Address for a specific range of IP addresses. Select Subnet Address
to specify IP addresses on a network by their subnet mask.
Starting IP Address When the Address Type field is configured to Single Address, enter a (static)
IP address on the network behind the remote IPSec router. When the Addr Type
field is configured to Range Address, enter the beginning (static) IP address, in
a range of computers on the network behind the remote IPSec router. When the
Address Type field is configured to Subnet Address, enter a (static) IP
address on the network behind the remote IPSec router.
Ending IP Address/
Subnet Mask
When the Address Type field is configured to Single Address, this field is N/A.
When the Address Type field is configured to Range Address, enter the end
(static) IP address, in a range of computers on the network behind the remote
IPSec router. When the Address Type field is configured to Subnet Address,
enter a subnet mask on the network behind the remote IPSec router.
Remote Port 0 is the default and signifies any port. Type a port number from 0 to 65535 in the
Start and End fields. Some of the most common IP ports are: 21, FTP; 53, DNS;
23, Telnet; 80, HTTP; 25, SMTP; 110, POP3
IPSec Proposal
Encapsulation Mode Select Tunnel mode or Transport mode.
Active Protocol Select the security protocols used for an SA.
Both AH and ESP increase ZyWALL processing requirements and
communications latency (delay).
Encryption Algorithm When DES is used for data communications, both sender and receiver must
know the same secret key, which can be used to encrypt and decrypt the
message or to generate and verify a message authentication code. The DES
encryption algorithm uses a 56-bit key. Triple DES (3DES) is a variation on DES
that uses a 168-bit key. As a result, 3DES is more secure than DES. It also
requires more processing power, resulting in increased latency and decreased
throughput. This implementation of AES uses a 128-bit key. AES is faster than
3DES. Select NULL to set up a tunnel without encryption. When you select
NULL, you do not enter an encryption key.
Authentication
Algorithm
MD5 (Message Digest 5) and SHA1 (Secure Hash Algorithm) are hash
algorithms used to authenticate packet data. The SHA1 algorithm is generally
considered stronger than MD5, but is slower. Select MD5 for minimal security
and SHA-1 for maximum security.
SA Life Time
(Seconds)
Define the length of time before an IKE SA automatically renegotiates in this
field. The minimum value is 180 seconds.
A short SA Life Time increases security by forcing the two VPN gateways to
update the encryption and authentication keys. However, every time the VPN
tunnel renegotiates, all users accessing remote resources are temporarily
disconnected.
Perfect Forward
Secret (PFS)
Perfect Forward Secret (PFS) is disabled (None) by default in phase 2 IPSec
SA setup. This allows faster IPSec setup, but is not so secure.
Select DH1 or DH2 to enable PFS. DH1 refers to Diffie-Hellman Group 1 a 768
bit random number. DH2 refers to Diffie-Hellman Group 2 a 1024 bit (1Kb)
random number (more secure, yet slower).
Enable Replay
Detection
As a VPN setup is processing intensive, the system is vulnerable to Denial of
Service (DOS) attacks The IPSec receiver can detect and reject old or duplicate
packets to protect against replay attacks. Enable replay detection by setting this
field to YES.
Table 44 VPN Rules (IKE): Add Policy (continued)
LABEL DESCRIPTION