Why do I have to have a firewall port open?

I checked the internet logs and there is a lot of activity going on from an NTP port. Is this normal? Or should I close that port? And if so, where would I find it on a Cisco EA4500 if I've already got it on Port lights off?

I found this on the net:

Q. If a guest anchor controller is used outside the firewall, what firewall ports are open for guest access to work?

A. On any firewall between the guest anchor controller and the remote controllers, these ports need to be open:

IP Protocol 97 for user data traffic

UDP Port for tunnel control traffic

For optional management, these firewall ports need to be open:

SSH/Telnet—TCP Port 22/23

TFTP—UDP Port 69

NTP—UDP Port 123

SNMP—UDP Ports 161 (gets and sets) and 162 (traps)

HTTPS/HTTP—TCP Port 443/80

Syslog—TCP Port 514

RADIUS Auth/Account UDP Port 1812 and 1813
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