Comming from a Cisco background, SAT was always use to redirect a source port to an internal private port for secure communication.
Eg, port 223 from WAN IP to port 22 on SSH linux box.
NAT however, is used for Port Overload reasons, in other words, you NAT the inside and outside interfaces so it can translate the private address to a public address with a dynamic source port.
Is this the same concept for DFL-800? I am just seeing how the previous employee set this up, and count me as confused.
He has the following RULES to get SMTP traffic through to the exchange server.
1 SAT_mail SAT lan lannet wan2 mail_wan2_ip all_services
2 NAT_mail NAT lan lannet wan2 mail_wan2_ip all_services
3 SAT_smtp SAT any smtp_trustedhosts wan2 mail_wan2_ip smtp-in
4 NAT_smtp NAT any smtp_trustedhosts wan2 mail_wan2_ip smtp-in
5 allow_smtp Allow any smtp_trustedhosts wan2 mail_wan2_ip smtp-in
I don't understand why all these rules are needed just to route SMTP mail from the outside to the inside. Why does it need a SAT rule, then a NAT rule, and then an ALLOW rule?
If someone can please explain this that will be great.