NTP (Network Time Protocol) is used to synchronize the system time with other devices over the network, this usually happens in a client-server model.
|caps||No||Use Linux capabilities library to control privilege|
|debug||No||No||Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see http://www.gentoo.org/proj/en/qa/backtraces.xml|
|ipv6||Yes||Adds support for IP version 6|
|openntpd||No||Allow ntp to be installed alongside openntpd|
|parse-clocks||No||Add support for PARSE clocks|
|samba||No||Provide support for Samba's signing daemon (needed for Active Directory domain controllers)|
|selinux||No||!!internal use only!! Security Enhanced Linux support, this must be set by the selinux profile or breakage will occur|
|snmp||No||Adds support for the Simple Network Management Protocol if available|
|ssl||Yes||Adds support for Secure Socket Layer connections|
|vim-syntax||No||Pulls in related vim syntax scripts|
|zeroconf||No||Support for DNS Service Discovery (DNS-SD)|
Or alternatively, you can use net-misc/openntpd instead.
The only configuration file is /etc/ntp.conf which is well explained with comments. Here are some of the more important settings.
Here you can specify with which servers you want to synchronize your local time.
Per default the gentoo servers are listed and enabled. A list of available servers can be found here: ntp.org You can also define a home or company server here, given that ntpd is running and the machine is allowed to.
To control who is allowed to synchronize with this machine and change the configuration, you can change these options.
- access to NTP service allowed only from localhost.
- access to NTP service allowed only from the 192.168.0.0/24 network.
Basic tools and common usage
Add ntpd to the default runlevel to have the time synchronized automatically
If ntpd is run as a service, the time will automatically synchronize as long as the difference between the local time and the time on the server is less than 1000s (~17min). So it is pretty common to adjust the time initially to whatever the server time is as a trusted source:
This used to be the client, but its functionality is now moved into ntpd itself. It is purely to set the local time when started and then exits (not a service):