Creating NTP Restrict Entries

Perform the following procedure to configure the NTP restrict capability for a specific IPv4 or IPv6 address(es), which means the switch permits NTP traffic flow from the specified IP addresses only. By default the NTP restrict capability is disabled.

Note

Note

  • You can configure a maximum of 128 NTP Restrict entries (IPv4 or IPv6 addresses).

  • 0.0.0.0/0 or ::/0 NTP restrict entries are equivalent to no NTP restrict rules configured.

Procedure

  1. Enter Global Configuration mode:

    enable

    configure terminal

  2. Configure a specific NTP restrict IP address:

    ntp restrict WORD<0-255>

  3. Verify the restricted IP address:

    show ntp restrict

Example

Switch:1>enable
Switch:1#configure terminal
Switch:1(config)#ntp restrict 192.0.0.0
Switch:1(config)#show ntp restrict
================================================================================
                            NTP Restrict Information
================================================================================
TYPE     ADDRESS                                    MASK/PREFIX LEN
--------------------------------------------------------------------------------
IPv4     192.0.0.0                                    23
--------------------------------------------------------------------------------

Variable Definitions

The following table defines parameters for the ntp restrict command:

Variable

Value

WORD<0-255>

Specifies the IPv4 or IPv6 address.
Note:

You can configure a maximum of 128 IPv4 and IPv6 addresses in the NTP restrict list.