Configuring Ntp Access Restrictions - Spectracom SecureSync User Reference Manual

Duplicate key IDs are not permitted. NTP requests received by that do not contain an authen-
ticator containing a valid Key ID and MD5 message digest pair will be responded to, but no authen-
tication will be performed. An NTP request with valid authenticators results in a valid NTP
response with its own valid authenticator using the same Key ID provided in the NTP request.
The user may define the trusted Symmetric Keys that must be entered on both SecureSync, and
any network client with which SecureSync is to communicate. The maximum number of Key-
ID/Key String pairs is 15. Only those keys for which the "Trusted" box has been checked will
appear in the dropdown menus on the NTP References screen.
3.4.12

Configuring NTP Access Restrictions

Next to encrypted authentication by means of Symmetric Keys, NTP supports a list-based means
of access restriction, the use of which is also recommended to prevent fraudulent or inadvertent
manipulation of a time server.
To configure NTP Access Restrictions:
1.
2.
CHAPTER •
3 SecureSync User Reference Guide Rev. 18
NOTE – In order for NTP configuration changes to take effect, NTP should be dis-
abled and then enabled after any configurations changes have been made.
NTP can be enabled and disabled through the NTP Services panel on the
MANAGEMENT/NETWORK/NTP Setup page. See "Enabling and Disabling NTP"
on page 120.
Changes made will take effect and NTP operation will be restored shortly after this
operation is performed.
Navigate to the MANAGEMENT/NETWORK/NTP Setup screen.
In the Actions panel, click the Access Restrictions button.
3.4 Network Time Protocol (NTP)
117