Default Ntp Configuration; Configuring Ntp Authentication - Cisco Catalyst 2950 Software Configuration Manual

Managing the System Time and Date

Default NTP Configuration

Table 7-2
Table 7-2
Feature
NTP authentication
NTP peer or server associations
NTP broadcast service
NTP access restrictions
NTP packet source IP address
NTP is enabled on all interfaces by default. All interfaces receive NTP packets.

Configuring NTP Authentication

This procedure must be coordinated with the administrator of the NTP server; the information you configure
in this procedure must be matched by the servers used by the switch to synchronize its time to the NTP server.
Beginning in privileged EXEC mode, follow these steps to authenticate the associations (communications
between devices running NTP that provide for accurate timekeeping) with other devices for security
purposes:
Command
Step 1
configure terminal
Step 2 ntp authenticate
Step 3 ntp authentication-key number md5 value
Step 4
ntp trusted-key key-number
Catalyst 2950 Desktop Switch Software Configuration Guide
7-36
shows the default NTP configuration.
Default NTP Configuration
Purpose
Enter global configuration mode.
Enable the NTP authentication feature, which is disabled by
default.
Define the authentication keys. By default, none are defined.
The switch does not synchronize to a device unless both have one
of these authentication keys, and the key number is specified by the
ntp trusted-key key-number command.
Specify one or more key numbers (defined in Step 3) that a peer
NTP device must provide in its NTP packets for this switch to
synchronize to it.
By default, no trusted keys are defined.
For key-number, specify the key defined in Step 3.
This command provides protection against accidentally
synchronizing the switch to a device that is not trusted.
Default Setting
Disabled. No authentication key is specified.
None configured.
Disabled; no interface sends or receives NTP broadcast packets.
No access control is specified.
The source address is determined by the outgoing interface.
For number, specify a key number. The range is 1 to
•
4294967295.
md5 specifies that message authentication support is provided
•
by using the message digest algorithm 5 (MD5).
For value, enter an arbitrary string of up to eight characters for
•
the key.
Chapter 7 Administering the Switch
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