Configure a Router with IPSec Using Pre-shared Keys
Steps to configure IPSec

The general tasks and commands used to configure IPSec encryption on Cisco routers are summarized as follows . Subsequent topics of this lesson discuss each configuration step in detail.

Step 1 Configure transform set suites with the crypto ipsec transform-set command.
Step 2 Configure global IPSec security association lifetimes with the crypto ipsec security-association lifetime command.
Step 3 Configure crypto ACLs with the access-list command.
Step 4 Configure crypto maps with the crypto map command.
Step 5 Apply the crypto maps to the terminating/originating interface with the interface and crypto map commands.