referring to own IP in filter rules

Hello,

Is there a convenient way to refer to my machine's own IP address in
diald filter rules, where the address is assigned dynamically by my ISP
when I dial in?

I've been using diald for several years and it works fine.  My problem
is that increasingly I find that the line is being kept up by attempted
connections from random sites.  I take it these are hackers, or machines
that have been hijacked by hackers.  As far as I can tell, my firewall
and tcp wrappers are successfully rejecting the connection attempts so
far, but diald is opening a connection set for them and giving it a
default timeout.  What I'd like to do is write a rule saying something
like "ignore any packet addressed to a port number lower than 900 on my
machine", but the address of my machine is different each time I dial
up.

I can imagine writing an ip-up script that uses sed to rewrite the
standard.filter file after the link comes up and then sends a reset to
diald.ctl, but that sounds messy and error-prone and I'd rather write
standard.filter to say what I really mean in the first place, if there
is some way of doing it.

Thanks.

Stephen Isard