How to Create DNAT rules using Waninterface IP address and forward SMTP (port 25) to internal server
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- create internal server name for the private server in Networks & Services --> Network Configuration.  i.e. private1 / 192.168.2.20 / 255.255.255.255

- create DNAT rule for the public ip address in Network Setup --> DNAT.  i.e  Any - WanInterface - SMTP - private1 - SMTP.   Repeat this step for other port you want to map.

- Save & restart to save all the settings and restart the routefinder


How to Create IP aliases and DNAT rules and forward SMTP (port 25) to internal server
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- create IP aliases for the other public IP address in Network Setup --> Advanced Ip Settings.  i.e. WAN1 /  40.22.1.1 / 255.255.255.255 

- create name for the public IP address in Networks & Services --> Network Configuration.  i.e.  public1 / 40.22.1.1 / 255.255.255.255

- create internal server name for the private server in Networks & Services --> Network Configuration.  i.e. private1 / 192.168.2.20 / 255.255.255.255

- create DNAT rule for the public ip address in Network Setup --> DNAT.  i.e  Any - public1 - SMTP - private1 - SMTP.   Repeat this step for other port you want to map.

- repeat the above steps for more mapping using the other public ip addreses.

- Save & restart to save all the settings and restart the routefinder




NOTE: when creating custom services, the source port of the service MUST be defined with 1:65535