How to open a port in Vyos?

General questions
1

Hello,

I have a Linux machine with SMTP on it and it’s connected to a Vyos machine as a firewall and I want to open SMTP port on that Vyos machine ?

How I can do that ?

Best Regards

2

You need both a destination NAT rule, to translate WAN IP address into server LAN IP address
And on firewall ruleset LAN_IN, you need a rule allowing the traffic.
Note NAT comes before firewall, so you should match on internal destination address/port in the rule

3

You need destination NAT. Please, refer to NAT — VyOS 1.2.x (crux) documentation for more information.