How to implement port triggering?

RouterOS Beginner Basics
1

Hello, everybody. I’d like to ask a question:
How to implement port triggering? Similar to the windows system “telnet 8.8.8.8 2345”

2

In Firewall, add a rule which adds the src ip of a connection to the trigger port with an appropriate timeout.
Then add an accept rule for the port which should then be open to be accessible by that address list only.

Example: you want port 80 only to be open after a trigger event on 12345:

/ip firewall filter
add action=add-src-to-address-list address-list=freeforaccess address-list-timeout=1h chain=input connection-state=new in-interface=ether1 port=12345 protocol=tcp
add action=accept chain=input protocol=tcp port=80 in-interface=ether1 src-address-list=freeforaccess

-Chris