Port 53
domain · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | domain |
Frequently asked questions
What is port 53 used for?
Port 53 is registered with the IANA for domain (TCP/UDP). Description: Domain Name Server.
Is port 53 a well-known port?
Yes. Port 53 is in the range 0–1023 (system or well-known ports). On Linux and macOS only privileged processes may bind to these ports.
How do I check whether port 53 is open?
Locally on Linux with ss -tulpn | grep ':53\b', on Windows with netstat -ano | findstr :53. To test a remote host use Test-NetConnection <host> -Port 53 in PowerShell or nc -zv <host> 53 on Linux/macOS.
How do I open port 53 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 53/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=53/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 53" -Direction Inbound -Protocol TCP -LocalPort 53 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | domain | Domain Name Server |
| UDP | domain | Domain Name Server |