howto get Caller ID from l2tp-server- binding conection

RouterOS Scripting
1

I have two mikrotika.
One has a static address, and other dynamically.
between them is the L2TP tunnel.
the Mikrotik static address to see CallerID second mikrotika but I can not pull out the script.

/ ppp active print
Flags: R - radius

NAME SERVICE CALLER-ID ADDRESS UPTIME ENCODING

0 name l2tp a.b.c.d 10.0.1.1 3m33s MPPE128 stateless

How to extract caller ID and put it to firewall rule?

2

For do what?

On Filter?
On NAT?
On Mangle?

To obtain the value:

:put [/ppp active get value-name=caller-id [find where name=> connection-name > ]]

3

the idea is to get out the current public address Mikrotik (which has no static) to be implemented in the firewall rule.
Thank you for your fast response