Port forward from specific, dynamic IP address

RouterOS Beginner Basics
1

Hello,

I have the following rule:

/ip firewall nat add chain=dstnat dst-address=50.50.50.50 protocol=udp dst-port=5060 action=dst-nat to-addresses=192.168.1.101 to-ports=5060 src-address=100.100.100.100

This works great, except that the src-address is a dynamic address. How can I limit a port forwarding rule to only work from a dynamic address?

Here is the what I am trying to accomplish if that helps. I have a VOIP PBX on a LAN behind a MikroTik router. I have a couple of phone extensions that are in homes outside of the LAN. These home have dynamic addresses. I would like to allow the required VOIP ports to be forwarded to the PBX but only from the specific homes.

Thanks.

2

How about setting up VPN’s from those houses to your router then allowing the packets to access the PBX? All other solutions I can think of will require the networks outside your network access to pass their IP addresses. Not a good security feature.

3

Thanks for the response. I could set up VPNs, but was hoping for something along the lines of a script that would check of myDynamicDNSClient.com every 30 minutes or so and update the firewall rule if needed.

The PBX actually has a feature like that I can use, so this is mostly an academic question. If I can do it all in RouterOS, it just seems a little more elegant.