Cisco Nexus 3548 series - Configuring NTP Access Restrictions

PurposeCommand or Action
Enables or disables the NTP authentication
feature. NTP authentication is disabled by
default.
switch(config)# [no] ntp authenticate
Step 6
Displays the status of NTP authentication.(Optional) switch(config)# show ntp
authentication-status
Step 7
Saves the change persistently through reboots
and restarts by copying the running
configuration to the startup configuration.
(Optional) switch(config)# copy
running-config startup-config
Step 8
Example
This example shows how to configure the device to synchronize only to time sources that provide
authentication key 42 in their NTP packets:
switch# config t
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# ntp authentication-key 42 md5 aNiceKey
switch(config)# ntp trusted-key 42
switch(config)# ntp authenticate
switch(config)# copy running-config startup-config
[########################################] 100%
switch(config)#
Configuring NTP Access Restrictions
You can control access to NTP services by using access groups. Specifically, you can specify the types of
requests that the device allows and the servers from which it accepts responses.
If you do not configure any access groups, NTP access is granted to all devices. If you configure any access
groups, NTP access is granted only to the remote device whose source IP address passes the access list criteria.
Procedure
PurposeCommand or Action
Enters global configuration mode.switch# configure terminal
Step 1
Creates or removes an access group to control
NTP access and applies a basic IP access list.
switch(config)# [no] ntp access-group {peer
| serve | serve-only | query-only}
access-list-name
Step 2
The access group options are scanned in the
following order, from least restrictive to most
restrictive. However, if NTP matches a deny
ACL rule in a configured peer, ACL processing
stops and does not continue to the next access
group option.
• The peer keyword enables the device to
receive time requests and NTP control
Cisco Nexus 3548 Switch NX-OS System Management Configuration Guide, Release 7.x
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Configuring NTP
Configuring NTP Access Restrictions