Domain Time II offers exclusive security features to ensure that your network's time is correct and resistant to both intentional and inadvertent
interference from other sources.
The Domain Time II Control Panel Applet - Security Settings Tab
One of the most common way that time messages are interfered with on a network is the concurrent operation of other time servers. Domain Time II
avoids this kind of problem by implementing a client-request/server-response structure for time updates.
Unlike many time systems that depend upon a time broadcast from a server to passively listening clients, Domain Time II servers do not broadcast
time (unless configured to do so by the administrator - see the When to use Heartbeats
and NTP Broadcasts page). Instead, servers wait for requests from clients before providing the time, and clients only accept time from the server that they made the request of.
This has several advantages:
- Clients cannot be confused by broadcasts from an extraneous time server
- Network traffic is minimized
- Both servers and clients can keep records of the transaction
In addition to the built-in protection of the system basic design, there are these additional protections against tampering/interference with your
Denial of Service (Flooding) Protection
Another way that your time service can be affected are by Denial of Service (DoS) attacks. DoS attacks are attempts to disable your system's
operation by flooding the system with bogus and/or malformed messages. Domain Time II protects against these kind of attacks by not
allowing any system to monopolize its resources. Any system that exceeds the DoS traffic thresholds you specify has its access automatically
blocked for a period of time. Both Domain Time Clients and Servers have this protection.
Your time service can potentially be degraded by responding to time requests from clients or servers on other network subnets over which you
have little control. For example, this can happen if your Domain Time server is accessible from a public network and many other users
discover and start to use your server as a time source.
Advanced - Command Restrictions
When you click on the Advanced button on the Domain Time II Server Security tab, you'll be presented with the Command Restrictions
dialog window. You can use these settings to restrict what kind of Domain Time II control and sync messages your server listens for on the network.
The Domain Time II Server - Command Restrictions Page
The default protocol restriction settings assure both maximum functionality and a high degree of security; in most cases you will have no need to adjust them from the defaults.
Domain Time II components communicate with each other primarily through directed communication, and are therefore highly resistant to spoofing and malign
The Domain Time II protocol command restriction capability is intended for use by system administrators in environments where an extra level of
security is required, such as running a Server on the open Internet. Using the restrictions list, you can determine exactly what Domain Time II protocol
command messages the service is allowed to listen for. Think of the command restriction list as an application-level "firewall" allowing in only the
desired Domain Time II commands and blocking any others. Keep in mind that the restriction list only affects incoming DTII protocol commands - outgoing
commands are not affected.
Disabling protocol commands can have unintended consequences on the operation of your entire time distribution network, including the prevention
of cascade triggers and sync notifications, which may result in inaccurate clocks. Problems resulting from disabled protocol messages can be quite
hard to troubleshoot later, particulary by the next system administrator after you. Make adjustments only if you understand and require them, and be
sure you document the changes so you can maintain the consistency and smooth operation of your time network.
Proceed to the Broadcast Time page
Back to the Time Sources page