Typically firewalls are not configured by default to allow SNTP protocol messages. This prevents you from contacting or receiving messages from Internet time servers. In order to operate correctly using the standard SNTP protocol, you will need to get your firewall administrator to allow IP/UDP outbound packets to port 123, and inbound IP/UDP packets from port 123.
The following firewall incoming packet filter rule will allow you to connect using the SNTP protocol while maintaining the security of your site. Please note that for incoming packets the source refers to the time server, and the destination refers to your machine running as a client.
Firewall
Settings |
Source
(server)
|
Destination
(client)
|
| Protocol |
UDP
|
| IP Address |
Any
|
| Port |
= 123
|
> 1023
|
| Action |
Permit
|
Please note that if you do try to connect to an Internet time server and your firewall is not properly configured then your firewall administrator may notice the inbound connection attempts being blocked.