Port Checker
Check whether a TCP port is reachable from the internet. You see if it is open, closed or filtered, and how long the connection took. Enter a host and port such as example.com:443.
- Free
- No signup required
- Live port check
Common open port problems
Port shows filtered
Nothing answered within 5 seconds, which usually means a firewall drops the packets. Check the server's firewall (ufw, firewalld, Windows Firewall), the cloud security group (AWS, Google Cloud, Azure) and any network firewall in front of it.
Port shows closed
The host answered but refused the connection: nothing is listening on that port. Check the service is running and listening on the public interface, not only on 127.0.0.1 (for example bind-address in MySQL or listen in nginx).
Open on the server, closed from outside
Behind a home or office router, the port must be forwarded to the machine's local IP. Some ISPs also block common ports such as 25 or 80 on home connections, and CGNAT can make inbound connections impossible.
Wrong host or IP
The hostname points to a CDN or proxy, not your server. Cloudflare's proxy, for example, only accepts web traffic on specific ports. Check the server's own IP address to test it directly.
Database or admin port open to the world
If 3306 (MySQL), 5432 (PostgreSQL), 6379 (Redis) or 22 (SSH) shows open and you did not mean it, restrict it in the firewall to the addresses that need it.
How to check if a port is open
- Enter the host or public IP and the port, for example example.com:443 or 203.0.113.10:22.
- Click Check port.
- Read the result: open, closed or filtered, and the connect time.
- If it is not open, check the service, the firewall and any port forwarding, then test again.
What does an open port mean?
A port is a numbered entry point on a host. Services listen on well-known ports: 80 for HTTP, 443 for HTTPS, 22 for SSH, 25 and 587 for mail, 3306 for MySQL. A port check tries to open a TCP connection to one of them.
There are three possible answers. Open means the connection was accepted and a service is listening. Closed means the host replied that nothing is listening (a TCP reset). Filtered means no reply came back within 5 seconds, which almost always means a firewall silently dropped the attempt.
This checker tests one port at a time from TinyPing's server, so you see what the internet sees, not what your local network sees. It is not a port scanner, and private or local addresses are not allowed. It checks TCP only, not UDP.
Connecting to example.com (203.0.113.10) port 443 Result: open, connected in 24 ms
When to use a port checker
Setting up a game or home server
Confirm that port forwarding on your router works and the port is reachable from outside your network.
Opening a port on AWS or another cloud
After editing a security group or firewall rule, check that the port really opened, and only the one you meant.
Mail server cannot receive mail
Check that port 25 is open on your mail host. If it is filtered, the provider or a firewall is blocking it.
Locking down a database
Make sure 3306, 5432 or 6379 is not reachable from the public internet after a cPanel or VPS setup.
Check something else
- Website Down CheckerCheck if a website is down for everyone or just you, with status code, response time and final URL.
- Domain to IP LookupFind the IP addresses behind a domain: A and AAAA records with TTLs, the CNAME chain and reverse DNS.
- TLS Version CheckerSee which TLS versions a server accepts, from TLS 1.0 to TLS 1.3, and the cipher it picks for each.
- DNS LookupLook up A, AAAA, CNAME, MX, TXT, NS, CAA and SOA records for any domain, with TTLs, from public resolvers.
Frequently asked questions
What is the difference between closed and filtered?
Closed means the host actively refused the connection: it is reachable but nothing listens on that port. Filtered means no answer at all, usually a firewall dropping the packets.
Can I check UDP ports?
No. This checker opens TCP connections only. UDP has no handshake, so a reliable open or closed answer needs a reply from the specific service.
Can I scan all ports on my server?
No. It checks one port per request and is not a scanner. Use a tool such as nmap from a machine you control to scan your own servers.
Why is my port open locally but not from here?
Your local test does not pass through the router, ISP or cloud firewall. This check comes from the internet, so a firewall, missing port forward or a service listening only on 127.0.0.1 makes it fail here.
Can I check a private IP like 192.168.1.10?
No. Private and local addresses are not reachable from the internet and are refused. Enter your public IP and set up port forwarding to the local machine.
Watch the services that are not websites
Mail servers, databases, SSH and game servers do not answer HTTP. A TinyPing port monitor checks them every 5, 15 or 30 minutes and alerts you when:
- the port stops accepting connections
- a firewall change starts blocking it
- the host stops resolving
US$6.99 a month or US$47 a year per 50 monitors, team members free. 7-day free trial, no card needed.
Want alerts in team chat? Follow the guide for Slack or Google Chat.