On Fri, 7 Jan 2000, Chan Yiu Wah wrote:

> I am trying to write the  active-filter-in for my demand dial up to ISP. 
> However, I am not skill enough to work it out. Here is part of the 
> tcpdump and the pppd call to my local ISP.  Should I put the port number
> in the active-filter-in "ip 1514 or ip 60" and so on.  I need your help.

If i understand your meaning correctly, all you need is

active-filter   'not udp port ntp'

> active-filter-in "udp or (tcp and not tcp port ntp)"

ntpd uses udp exclusively.