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Configuring NTP Symmetric Keys

To create, edit, or delete Symmetric Keys (MD5 Authentication):

  1. Navigate to MANAGEMENT > NETWORK: NTP Setup.
  2. In the Actions panel, click the Symmetric Keys button:
  3. The NTP Symmetric Keys window will display:
    • To CREATE a Symmetric Key, click the PLUS icon in the top-right corner, and proceed to Step 4.
    • To EDIT an existing key pair, click the corresponding Change button, and proceed to Step 4.
    • To DELETE a key pair, click the corresponding Delete button, and click OK in the dialog box to confirm and complete the procedure.

  4. The NTP Symmetric Key window will display:
  5. Fill in, or edit the fields:

    • Trusted (checkbox)—Check this box to use MD5 authentication with trusted key ID.
    • Note: To use the MD5 authentication with trusted key ID, both the NTP client and the NetClock must contain the same key ID/key string pair, the client must be set to use one of these MD5 pairs, and the key must be trusted.

    • Key ID—The key ID must be a number between 1 and 65532.
    • Digest Scheme—Choose one of the options from the drop-down list. The available options are:
      • MD5 (the default)
      • SHA1
      • SHA
      • MDC2
      • MDC2
      • RIPEMD160
      • MD4
    • Key Str—The key string must be readable ASCII and between 1 and 16 characters long.

  6. Click the Submit button: The changes will be reflected in the table of the NTP Symmetric Keys window, which is displayed after clicking the Submit button.
  7. The key(s) you have set up will now appear as options in the Symmetric Key field in both the NTP Server screen, and the NTP Peer screen.


Duplicate key IDs are not permitted. NTP requests received by that do not contain an authenticator containing a valid Key ID and MD5 message digest pair will be responded to, but no authentication 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.

You may define the trusted Symmetric Keys that must be entered on both NetClock, and any network client with which NetClock is to communicate. Only those keys for which the “Trusted” box has been checked will appear in the dropdown menus on the NTP References screen.