Hi Avi, I use OpenVPN "http://www.openvpn.net/index.php/open-source.html"; to accomplish this. Ossec server is on local DMZ, Ossec agents on remote DMZ. Install OpenVPN server on your Ossec server. Install OpenVPN agents on your offsite systems. Configure OpenVPN server to listen on a port your offsite systems can access outbound. On my local DMZ firewall I limit access to the OpenVPN server port to trusted nets to keep out the riff-raff. Configure Ossec server to use the Ossec agents OpenVPN ip address. This setup can also then be used for other monitoring/management apps (Nagios,etc).
Jim
