MitraStar Movistar GPT-2541GNAC, User Manual

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Chapter 16 IPSec VPN 126
Finally, NAT is compatible with ESP in tunnel mode because integrity checks are performed over the
combination of the "original header plus original payload," which is unchanged by a NAT device. The
compatibility of AH and ESP with NAT in tunnel and transport modes is summarized in the following
table.
Table 72 VPN and NAT
SECURITY PROTOCOL MODE NAT
AH Transport N
AH Tunnel N
ESP Transport Y*
ESP Tunnel Y
Y* - This is supported in the Router if you enable NAT traversal.
16.3.7 ID Type and Content
With aggressive negotiation mode (see Section 16.3.4 on page 124 ), the Router identifies incoming
SAs by ID type and content since this identifying information is not encrypted. This enables the
Router to distinguish between multiple rules for SAs that connect from remote IPSec routers that
have dynamic WAN IP addresses.
Regardless of the ID type and content configuration, the Router does not allow you to save multiple
active rules with overlapping local and remote IP addresses.
With main mode (see Section 16.3.4 on page 124 ), the ID type and content are encrypted to provide
identity protection. In this case the Router can only distinguish between up to 12 different incoming
SAs that connect from remote IPSec routers that have dynamic WAN IP addresses. The Router can
distinguish up to 48 incoming SAs because you can select between three encryption algorithms
(DES, 3DES and AES), two authentication algorithms (MD5 and SHA1) and eight key groups when
you configure a VPN rule (see Section 16.1 on page 114 ). The ID type and content act as an extra
level of identification for incoming SAs.
The type of ID can be a domain name, an IP address or an e-mail address. The content is the IP
address, domain name, or e-mail address.
Table 73 Local ID Type and Content Fields
LOCAL ID
TYPE=
CONTENT=
IP Type the IP address of your computer.
DNS Type a domain name (up to 31 characters) by which to identify this Router.