Port53— DNS
Conventional DNS uses port 53 over UDP and TCP. Treating DNS as a UDP-only service can cause incomplete or intermittent resolution.
Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.
Configuration and troubleshooting
Inspect TCP and UDP listeners and firewall rules separately. If small queries work while others fail, test the TCP path too.
Important limitations
Restrict clients allowed to use a recursive resolver. Absence of a port-53 listener does not rule out encrypted DNS or another resolver path.
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
Software Using This Port (4 software)
Community software entries: links are references, not individual verification.
Usage Suggestions
- Before using port 53, please confirm it is not occupied by other services
- If you encounter port conflicts, consider using other ports or stopping the occupying service
Frequently asked questions
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.
Quick Info
- Port
- 53
- Protocol
- TCP/UDP
- Categories
- DNS Services
- Usage Status
- 4 software in use
Related Ports
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