KitsNet Operations:Services:Time

The common time configuration for KitsNet is organized around core network devices providing synchronized time to all other devices on the network. The authoritative sources for time are the core network switch (Courvoisier) and the Internet router (Radix). These are addressed via CNAMEs of time1.lan.kitsnet.us and time2.lan.kitsnet.us respectively. Additionally, the DHCP server is deployed with DHCP option 42 (see DHCP Options and BOOTP Vendor Extensions).

Previously, Wort was identified as a time source with CNAME time.lan.kitsnet.us, but this configuration is being deprecated.

1 Linux Clients

Linux clients with network interfaces configured via DHCP will pick up the NTP servers from their DHCP client request automatically. The identities of the NTP servers are written by the DHCP client to /var/run/chrony-helper/nm-dhcp.ifname prior to Rocky Linux v9.0 and /run/chrony-dhcp/ifname.sources for Rocky Linux v9.0 and above. The list of NTP servers currently referenced by chronic may be reviewed as follows:

[psmode@quadsec ~]$ chronyc sources -v

  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.
 / .- Source state '*' = current best, '+' = combined, '-' = not combined,
| /             'x' = may be in error, '~' = too variable, '?' = unusable.
||                                                 .- xxxx [ yyyy ] +/- zzzz
||      Reachability register (octal) -.           |  xxxx = adjusted offset,
||      Log2(Polling interval) --.      |          |  yyyy = measured offset,
||                                \     |          |  zzzz = estimated error.
||                                 |    |           \
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^+ courvoisier.lan.kitsnet.>     4   8   377    94  +1419us[+1385us] +/-   54ms
^* radix.kitsnet.us              3   6   377    32  -1135us[-1169us] +/-   26ms

2 Windows Clients

Windows clients are being handled a little differently. For these, we are using the default configuration for Active Directory which has the clients getting time from the AD controllers. These controllers are implemented on Linux servers with Samba, so they get their time via the DHCP client options as described above.

3 NTP Server Identification

The NTP servers are defined in two places: DHCP Options and DNS CNAMEs. For DHCP Options, the internal DHCP server has a DHCP Options specification that includes a stanza with tag 42 listing the IP addresses of the two NTP servers used on the LAN. For the DNS CNAMEs, the DNS server has CNAMEs for time1 and time2 pointing the the true hostnames that represent the addresses in the NTP Options specification.