[ale] NTP and 'ipchains'

[johnmills at speakeasy.net (John Mills)]

ALErs -

I'm running RH-7.3 and 'ipchains'. My LAN sits behind a firewall/router
that forwards only port 22 to serve incoming SSH. In order for 'ntpdate'
to successfully connect to outside servers, I had to add an 'ipchains'
rule:
 -A input -s 0/0 -d 0/0 123 -p udp -j ACCEPT

I didn't have to forward this port back through the router/firewall, 
however.

Was it normal to need such a rule when I don't need rules to pass other
sorts of replies, such as responses to telnet and http inquiries to other
hosts?

Thanks for any background on this.

 - John Mills
   john.m.mills at alum.mit.edu