How to use the Port Checker
- Enter a domain or public IP address.
- Enter the ports to test, or click a preset (web, mail, databases, remote access).
- Click Check ports. Each port gets a TCP connection attempt with a 3-second timeout.
- Read the result: open accepts connections, closed actively refuses, filtered doesn’t answer (usually a firewall).
Open, closed or filtered?
| Status | Meaning |
|---|---|
| Open | A service is listening and accepted the connection. |
| Closed | The host is reachable but refused the connection — nothing listens on that port. |
| Filtered | No answer within 3 seconds — a firewall silently drops the traffic, or the host is offline. |
Common ports
| Port | Service | Should usually be public? |
|---|---|---|
| 80 / 443 | HTTP / HTTPS | Yes, for websites |
| 25, 465, 587 | SMTP (mail transfer & submission) | On mail servers |
| 993 / 995 | IMAPS / POP3S | On mail servers |
| 22 | SSH | Only if needed — restrict by IP or key-only login |
| 3306, 5432, 1433, 27017, 6379 | MySQL, PostgreSQL, MS SQL, MongoDB, Redis | Almost never — keep databases private |
| 3389, 5900 | RDP, VNC | No — a frequent attack target |
Use it responsibly
Check servers you own or administer — for example to verify a firewall rule, port forwarding on a router, or that a database isn’t exposed. The tool tests a short list of ports only and is rate-limited; it’s not a full scanner. For web-specific checks see the SSL Checker, Security Headers Checker and Ping Test.
Also searched as: open port checker, check open ports, port scanner online, is port open, test port, port 25 check, port forwarding test.
Common ports
What each well-known port is used for, whether to expose it, and how to check it:
- Port 21: FTP
- Port 22: SSH / SFTP
- Port 23: Telnet
- Port 25: SMTP
- Port 53: DNS
- Port 80: HTTP
- Port 110: POP3
- Port 123: NTP
- Port 143: IMAP
- Port 161: SNMP
- Port 389: LDAP
- Port 443: HTTPS
- Port 445: SMB
- Port 465: SMTPS
- Port 587: SMTP submission
- Port 636: LDAPS
- Port 853: DNS over TLS
- Port 993: IMAPS
- Port 995: POP3S
- Port 1194: OpenVPN
- Port 1433: Microsoft SQL Server
- Port 1521: Oracle Database
- Port 1883: MQTT
- Port 2049: NFS
- Port 3000: Development servers
- Port 3306: MySQL / MariaDB
- Port 3389: Remote Desktop (RDP)
- Port 5000: Development servers / AirPlay
- Port 5432: PostgreSQL
- Port 5672: AMQP (RabbitMQ)
- Port 5900: VNC
- Port 6379: Redis
- Port 8000: HTTP alternate / dev servers
- Port 8080: HTTP alternate
- Port 8443: HTTPS alternate
- Port 8883: MQTT over TLS
- Port 9000: PHP-FPM / various
- Port 9200: Elasticsearch
- Port 11211: Memcached
- Port 25565: Minecraft (Java Edition)
- Port 27017: MongoDB
- Port 51820: WireGuard
Tools that pair well with the Port Checker
- SPF, DKIM & DMARC Checker — Find out why emails land in spam.
- Website Down Checker — Find out in seconds whether a website is down for everyone or just for you — with status code, response time and troubleshooting tips.
- DNS Lookup — Query all common DNS record types for a domain in one go, with TTLs, sorted MX records and an SPF/DMARC email-authentication summary.
- Email Header Analyzer — Paste the raw headers of an email to see its whole journey: every server hop with the time it took, the SPF, DKIM and DMARC results, the originating IP, and warning signs like a mismatched Reply-To or Return-Path.
Frequently asked questions
How do I check if a port is open?
Enter the host and the port numbers, then click Check ports. “Open” means a service accepted the connection from the internet.
Why is my port shown as filtered?
No response arrived within 3 seconds. A firewall (on the server, your hosting provider or router) is probably dropping the traffic, or the device is offline.
Can I test port forwarding on my home router?
Yes — enter your public IP (see What Is My IP) and the forwarded port while the service is running. Private addresses like 192.168.x.x can’t be tested from the internet.
Why is port 25 blocked?
Many ISPs and cloud providers block outgoing or incoming port 25 to fight spam. Mail clients should use 587 (submission) or 465 instead.