Technical Documentation

Configuring NTP Authentication Keys

Time synchronization can be authenticated to ensure that the local router or switch obtains its time services only from known sources. By default, network time synchronization is unauthenticated. The system will synchronize to whatever system appears to have the most accurate time. We strongly encourage you to configure authentication of network time services.

To authenticate other time servers, include the trusted-key statement at the [edit system ntp] hierarchy level. Only time servers transmitting network time packets that contain one of the specified key numbers and whose key matches the value configured for that key number are eligible to be synchronized to. Other systems can synchronize to the local router without being authenticated.

[edit system ntp]trusted-key [ key-numbers ];

Each key can be any 32-bit unsigned integer except 0. Include the key option in the peer, server, or broadcast statements to transmit the specified authentication key when transmitting packets. The key is necessary if the remote system has authentication enabled so that it can synchronize to the local system.

To define the authentication keys, include the authentication-key statement at the [edit system ntp] hierarchy level:

[edit system ntp]authentication-key key-number type type value password;

number is the key number, type is the authentication type (only Message Digest 5 [MD5] is supported), and password is the password for this key. The key number, type, and password must match on all systems using that particular key for authentication.

Published: 2010-04-26