Did you follow the guide how to install strongSwan 5 on Debian Wheezy? You may have noticed that strongSwan doesn’t automatically start when you reboot the server (tested with 5.1.0-3~bpo70+1). The fix requires a small modification to /etc/init.d/ipsec.

Change:

# Provides:          ipsec
# Required-Start:    $network $remote_fs
# Required-Stop:     $network $remote_fs

To:

# Provides:          ipsec
# Required-Start:    $network $remote_fs $syslog
# Required-Stop:     $network $remote_fs $syslog

Then reinitialize the boot sequence for ipsec:

$ insserv -r ipsec
$ insserv ipsec