Configuring KOD
Context
The Kiss-o'-Death (KOD) is a brand new access control technology starting from NTPv4, and is mainly used for a server to provide information, such as a status report and access control, for a client.
After the KOD is enabled on the server, the server sends the kiss code DENY or the kiss code RATE to the client according to the operating status of the system.
The client responds differently to different kiss codes:
- When receiving the kiss code DENY, the client terminates all connections with the server, and stops sending packets to the server.
- When receiving the kiss code RATE, the client immediately shortens a poll interval with the server. Every time the kiss code RATE is received after the first shortening operation, the poll interval is further shortened.
NOTE: The KOD supports the unicast client/server mode, and symmetric peer mode.
The KOD only functions in NTPv4.
The following configuration is performed on the server.
Procedure
- Run system-view
The system view is displayed.
- Run ntp kod-enable
The KOD function is enabled.
By default, the KOD function is disabled.
- Configure the basic ACL.
Before configuring the access control authority, you must create a basic ACL. For the creation procedure, see "ACL Configuration" in the CloudEngine 8800, 7800, 6800, and 5800 Series Switches Configuration Guide-Security.
- Run ntp access limited { { acl-number | acl-name acl-name } | ipv6 { acl6-number | acl6-name acl6-name } }*
Control on the rate of incoming NTP packets is enabled.
By default, control on the rate of incoming NTP packets is disabled.
Before enabling control on the rate of incoming NTP packets, check the ACL rule configuration. When the ACL rule is deny, the server sends the kiss code DENY. When the ACL is permit and the rate of incoming NTP packets reaches the upper threshold, the server sends the kiss code RATE.
- Run ntp discard { min-interval min-interval-val | avg-interval avg-interval-val } *
The minimum inter-packet interval and the average inter-packet interval of NTP are configured.
By default, the minimum inter-packet interval of NTP is set to the first power of 2 in seconds, namely, 2 seconds, and the average inter-packet interval of NTP is set to the fifth power of 2 in seconds, namely, 32 seconds.
- Run commit
The configuration is committed.
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