Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual page 290

Figure 20.1 Advanced NTP Configuration: Security Settings
In the Security Settings tab, determine whether ntpd should be started in a chroot jail.
By default, Run NTP Daemon in Chroot Jail is activated. This increases the security
in the event of an attack over ntpd, as it prevents the attacker from compromising the
entire system.
Restrict NTP Service to Configured Servers Only increases the security of your system
by disallowing remote computers to view and modify NTP settings of your computer
and to use the trap facility for remote event logging. Once enabled, these restrictions
apply to all remote computers, unless you override the access control options for indi-
vidual computers in the list of time sources in the General Settings tab. For all other
remote computers, only querying for local time is allowed.
Enable Open Port in Firewall if SuSEfirewall2 is active (which it is by default). If you
leave the port closed, it is not possible to establish a connection to the time server.
276 Administration Guide