Port 853
domain-s · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | domain-s |
| Reference | RFC 7858, RFC 7858, RFC 8094, RFC 9250 |
| Registered | 2015-10-08 |
| Modified | 2022-04-11 |
Frequently asked questions
What is port 853 used for?
Port 853 is registered with the IANA for domain-s (TCP/UDP). Description: DNS query-response protocol run over TLS; DNS query-response protocol run over DTLS or QUIC.
Is port 853 a well-known port?
Yes. Port 853 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 853 is open?
Locally on Linux with ss -tulpn | grep ':853\b', on Windows with netstat -ano | findstr :853. To test a remote host use Test-NetConnection <host> -Port 853 in PowerShell or nc -zv <host> 853 on Linux/macOS.
How do I open port 853 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 853/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=853/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 853" -Direction Inbound -Protocol TCP -LocalPort 853 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | domain-s | DNS query-response protocol run over TLS |
| UDP | domain-s | DNS query-response protocol run over DTLS or QUIC |