KEA DHCP NTP-Konfiguration - Netzwerk und Serveradministration

NTP-Server via Kea DHCP verteilen

Übersicht

Kea DHCP kann NTP-Server-Informationen an DHCP-Clients verteilen. Dies ermöglicht eine zentrale Zeitserver-Konfiguration für alle Netzwerkgeräte.

DHCP-Option für NTP

• Option 42 (DHCPv4): NTP Servers
• Format: Liste von IPv4-Adressen

Konfiguration

Globale NTP-Konfiguration

NTP-Server für alle Subnetze:

• sudo vim /etc/kea/kea-dhcp4.conf

{
  "Dhcp4": {
    "interfaces-config": {
      "interfaces": [ "enp0s3" ]
    },
    "control-socket": {
      "socket-type": "unix",
      "socket-name": "/run/kea/kea4-ctrl-socket"
    },
    "lease-database": {
      "type": "memfile",
      "persist": true,
      "name": "/var/lib/kea/kea-leases4.csv"
    },
    "valid-lifetime": 7200,
    "option-data": [
      { "name": "domain-name-servers", "data": "10.88.2XX.21" },
      { "name": "domain-name", "data": "it2XX.int" },
      { "name": "domain-search", "data": "it2XX.int" },
      { "name": "ntp-servers", "data": "ntp.it2XX.int" }
     ],
    "subnet4": [
      {
        "id": 1,
        "subnet": "172.26.2XX.0/24",
        "pools": [ { "pool": "172.26.2XX.100 - 172.26.2XX.200" } ],
        "option-data": [ { "name": "routers", "data": "172.26.2XX.1" } ],
        "reservations": [
          { "hw-address": "08:00:27:5d:76:5d", "ip-address": "172.26.2XX.99", "hostname": "client" }
        ]
      },
      {
        "id": 2,
        "subnet": "10.88.2XX.0/24",
        "pools": [ { "pool": "10.88.2XX.50 - 10.88.2XX.100" } ],
        "option-data": [ { "name": "routers", "data": "10.88.2XX.1" } ]
      },
      {
        "id": 3,
        "subnet": "10.2XX.1.0/24",
        "pools": [ { "pool": "10.2XX.1.50 - 10.2XX.1.100" } ],
        "option-data": [ { "name": "routers", "data": "10.2XX.1.1" } ]
      }
    ],
    "loggers": [
      {
        "name": "kea-dhcp4",
        "output_options": [ { "output": "/var/log/kea/kea-dhcp4.log" } ],
        "severity": "INFO"
      }
    ]
  }
}

Dienst neu starten

• Konfiguration testen
• sudo kea-dhcp4 -t /etc/kea/kea-dhcp4.conf

• Dienst neu starten
• sudo systemctl restart kea-dhcp4-server

• Status prüfen
• sudo systemctl status kea-dhcp4-server

Überprüfung auf dem Client

Linux Client

• DHCP-Informationen anzeigen
• cat /var/lib/dhcp/dhclient.leases

oder

• ip addr show

• NTP-Status prüfen (wenn systemd-timesyncd verwendet wird)
• timedatectl status

Erwartete Ausgabe:

               Local time: Mo 2025-10-20 15:30:45 CET
           Universal time: Mo 2025-10-20 13:30:45 UTC
                 RTC time: Mo 2025-10-20 13:30:45
                Time zone: Europe/Berlin (CET, +0100)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

• Konfigurierte NTP-Server anzeigen
• timedatectl show-timesync --all

Windows Client

• PowerShell als Administrator öffnen
• ipconfig /all

Im Output nach "DHCP-Server" und unter "Optionen" suchen.

• NTP-Konfiguration prüfen
• w32tm /query /status