How do I find my local IP assigned by my ISP when using pon, etc?

["Randolph S. Kahle" <RandyKahle@KahleAssociates.com>]

I am running potato and trying to configure dial-up Internet access.

Everything is running fine - I can dial the ISP, authenticate, get an IP
address, etc.

Now I am trying to write firewall rules that will adapt to whatever IP I
am assigned.

I think I am two questions away from getting this to work:

    * What script is run when the connection to the ISP completes?
    
    * How do I know, in that script, what my assigned IP is?

I see that there are directories /etc/ppp/ip-up.d and
/etc/ppp/ip-down.d. What is the function of those directories? Are the
scripts in those directories all run on "up" and "down" state
transitions for ppp?

-- Randy