pfSense

When you enter a value in the retries field of the "Dead Peer Detection" row in the edit form on vpn_ipsec_phase1.php and save it, whatever value you enter gets put into /var/etc/ipsec/ipsec.conf as the value of dpdtimeout under the appropriate connection.

Racoon had a configuration parameter that was the maximum number of failures that mapped to the retries field, but strongswan has a total timeout value instead. The value that should be populated in the config file should be: (number of retries + 1) * dpd delay. Or the field in the GUI should be changed to reflect that it's a total timeout value instead of a number of retries.