Port53— DNS
Le DNS classique utilise le port 53 en UDP et en TCP. Le considérer comme un service uniquement UDP peut entraîner une résolution incomplète ou intermittente.
Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.
Configuration and troubleshooting
Vérifiez séparément les sockets d’écoute et les règles de pare-feu TCP et UDP. Si les petites requêtes aboutissent mais pas les autres, testez aussi le chemin TCP.
Important limitations
Limitez les clients autorisés à utiliser un résolveur récursif. L’absence d’écoute sur le port 53 n’exclut pas l’utilisation de DNS chiffré ou d’un autre chemin de résolution.
Read-only checks: run on the server host
Choose the commands for your OS. Check TCP and UDP separately. No result is not a lasting availability guarantee; inspect host and container separately.
Linux
sudo ss -ltnp 'sport = :53'
sudo ss -lunp 'sport = :53'macOS
sudo lsof -nP -iTCP:53 -sTCP:LISTEN
sudo lsof -nP -iUDP:53Windows PowerShell
Get-NetTCPConnection -LocalPort 53 -State Listen
Get-NetUDPEndpoint -LocalPort 53Sources and review
Sources checked on:
This review covers the explanations and sources on this page, not your device or every community software entry below.
Related troubleshooting guides
Logiciels utilisant ce port (4 logiciels)
Community software entries: links are references, not individual verification.
Conseils d’utilisation
- Avant d’utiliser le port 53, vérifiez qu’il n’est pas occupé par d’autres services
- En cas de conflit de ports, envisagez d’utiliser d’autres ports ou d’arrêter le service qui occupe le port
Questions fréquentes
What is port 53 used for?
Port 53 sits in the DNS Services category. This page lists the registered purpose and the software commonly associated with it; to see what is actually listening on a specific machine, check the process with ss/netstat.
Is port 53 TCP or UDP?
The registered protocol on this page is TCP / UDP. The same number behaves independently on each protocol: TCP may be listening while UDP is idle, so check them separately.
How do I check if port 53 is in use?
On Linux: sudo ss -tlnp 'sport = :53' for an exact port match. On macOS: sudo lsof -nP -iTCP:53 -sTCP:LISTEN. On Windows PowerShell: Get-NetTCPConnection -LocalPort 53 -State Listen. A listener counts as confirmed only when you can see the bind address and process name; without root/admin you will not see other users' processes.
Is port 53 secure? Should I open it in my firewall?
A port number has no inherent security — it depends on whether the listening service is correctly configured and whether it needs exposure at all. Keep loopback/internal-only services firewalled; where public access is required, pair it with source restrictions, VPN or authentication. The caution section on this page lists port-specific risks.
En bref
- Port
- 53
- Protocole
- TCP/UDP
- Catégories
- Services DNS
- État d’utilisation
- 4 logiciels utilisant ce port
Ports associés
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