Usage Scenario
Compared with NTP authentication, the ntp-service access command is simpler to implement network security. When receiving an access query, an NTP server matches it with peer, query, server, and synchronization in descending order of access restriction strictness.
Precautions
Use this command based on the access limitation.
- Unicast NTP server or client mode: In client, the restricted NTP query is synchronizing the client with the server.
- Unicast NTP server or client mode: In server, the restricted NTP query is clock synchronization request from the client.
- NTP peer mode: In symmetric active end, the restricted NTP query is clock synchronization with each other.
- NTP peer mode: In symmetric passive end, the restricted NTP query is clock synchronization request from the active end.
- NTP multicast mode: In NTP multicast client, the restricted NTP query is synchronizing the client with the server.
- NTP broadcast mode: In NTP broadcast client, the restricted NTP query is synchronizing the client with the server.
- NTP manycast mode: In NTP manycast client, the restricted NTP query is synchronizing the client with the server.
- NTP manycast mode: In NTP manycast Server, the restricted NTP query is clock synchronization request from the client.
If this command is the first NTP configuration command, the system automatically adds the ntp-service server disable/ntp-service ipv6 server disable command in the configuration file to disable the NTP service. If this command is the last NTP configuration command to be deleted, the system automatically deletes the ntp server disable/ntp ipv6 server disable command from the configuration file.
Before configuring access control rights in an ACL, check the ACL rule configuration.
- If the ACL rule of a source IP address is set to permit, packets from the source IP address are permitted.
- If the ACL rule of a source IP address is set to deny, packets from the source IP address are denied.
- If a source IP address is not in an ACL rule, packets from the source IP address are denied.
- If no rule exists in the ACL or the referenced ACL does not exist, packets from all source IP addresses are denied.