Fortinet FortiGate FortiGate-100A, Руководство администратора

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VPN Configuring redundant IPSec VPNs
FortiGate-100A Administration Guide 01-28006-0068-20041105
289
Consider the following example, which shows two physically separate networks. The
IP addresses of the computers on both networks are in the 192.168.12.0/24 range,
but no two IP addresses are the same. An IPSec VPN has been configured between
FortiGate_1 and FortiGate_2. The FortiGate configuration permits Host_1 on the
Finance network to transmit data to Host_2 on the HR network through the IPSec
VPN tunnel.
Figure 140:A typical site-to-site configuration using the IPSec VIP feature
When Host_1 attempts to send a packet to Host_2 for the first time, Host_1 issues an
ARP request locally for the MAC address of Host_2. However, because Host_2
resides on a remote network, it does not respond. Instead, the FortiGate unit
responds with its own MAC address. From that point, Host_1 adds the MAC address
of the FortiGate unit to its ARP cache and the FortiGate unit will act as a proxy for
Host_2.
In the above example, the private IP addresses between the two sites have been
coordinated to protect against ambiguous routing (no two IP addresses are the same).
Setting up a configuration like this involves performing the following tasks at
FortiGate_1 and FortiGate_2:
To enable IPSec VPN communication between two network hosts that coordinate the
same private address space on physically separate networks, perform the following
tasks at the local and remote FortiGate units:
1 On both FortiGate units, define the gateway/tunnel on which to transmit VPN traffic to
the remote location (see
“Phase 1” on page 246 and “Phase 2” on page 250 ).
2 On both FortiGate units, define the firewall encrypt policy that is needed to select and
enable communication through the defined VPN gateway/tunnel (see
“Firewall” on
page 189 ).
3 Using CLI commands to configure the local FortiGate unit, add VIP entries to define
which IP addresses can be accessed at the remote end of the VPN tunnel (see
“ipsec
vip” on page 276 ). For example, to enable access to Host_2 on the HR network from
Host_1 on the Finance network, enter the following CLI commands on FortiGate_1:
Esc Enter
Host_2
192.168.12.2
external
Host_1
192.168.12.1
FortiGate_1
external
Esc Enter
FortiGate_2
Finance Network
192.168.12.0/24
HR Network
192.168.12.0/24
Internet