Port Checker
Check whether a TCP or UDP port on a host or IP address is open and reachable from the Internet — a real connection attempt from our server, not a guess.
Enter a host or IP address and a port number, choose TCP or UDP, and run the check to see whether it’s open.
Attempting to connect…
This check runs from Pingvero’s own server, not from your device — it shows whether a port is reachable from the wider Internet, which is not the same as whether it’s open on your local network. TCP results (open/closed) come from a real connection attempt and are reliable. UDP has no handshake, so a UDP result of “no response” is genuinely inconclusive rather than a sign the port is closed — see “TCP vs UDP Ports” below.
Quick Explanation
A port checker is a tool that tests whether a specific network port on a host or IP address will accept a connection. Every device that offers a service on a network — a website, a mail server, a game, a remote-access tool — does so on a numbered port, and a port checker simply attempts to connect to that port and reports what happens.
The result falls into one of a few outcomes: the port is open (something accepted the connection), closed (the connection was actively refused), filtered (a firewall is silently blocking it, so no answer arrives either way), or a timeout (no response within a reasonable time, which looks the same as filtered from the outside). This tool tells the four apart wherever it genuinely can, and says so plainly when it can’t.
Method
Five steps, no installation required.
Enter the hostname or IP address you want to test — your own server, a domain, or any public address.
Enter the port number you want to check, from 1 to 65535.
Select the protocol: TCP for most web, mail and remote-access services, or UDP for services like DNS, VoIP or game servers that use it.
Click “Check Port” to run a real connection attempt from our server.
Read the result: open, closed, or filtered/no response — each explained in plain language, with no invented status.
See our Methodology page for how every Pingvero tool measures your connection.
Basics
Every device connected to a network has an IP address — a way to be found. A port is a number, from 1 to 65535, that identifies a specific service or application running on that device. If the IP address gets data to the right computer, the port gets it to the right program running on that computer: web traffic to the web server, mail to the mail server, and so on, all sharing the same IP address without interfering with each other.
Ports work with either of two protocols. TCP (Transmission Control Protocol) sets up a reliable, confirmed connection before any data flows — used by web browsing, email and file transfer. UDP (User Datagram Protocol) sends data immediately with no setup and no confirmation of delivery — used where speed matters more than guaranteed delivery, like DNS queries, VoIP calls and many online games. A service is the software listening on a given port for that traffic; client/server communication is simply one device (the client) connecting to a specific IP address and port on another (the server) to use that service.
A handful of ports are reserved by convention for well-known services: port 80 for HTTP, 443 for HTTPS, 22 for SSH, 25 for SMTP, 53 for DNS, and 3389 for Remote Desktop. See the full reference table further down this page.
Protocols
TCP opens a connection with a handshake before any data is sent, and confirms every packet is delivered, in order. That handshake is exactly what a port checker relies on: a completed connection reliably means “open”, and an explicit refusal reliably means “closed”. Used by HTTP/HTTPS, SSH, email and most everyday services.
UDP sends a packet with no handshake and no guarantee it arrives or that anything replies — that’s what makes it fast, and it’s also what makes it hard to test. A UDP service that’s working perfectly may simply ignore an unexpected probe, so “no response” can mean open, filtered, or genuinely closed. Used by DNS, NTP, VoIP and many online games.
In short: a TCP check gives you a dependable yes-or-no answer. A UDP check can confirm a port is open if it gets a reply, but silence doesn’t prove the port is closed — that ambiguity is a property of UDP itself, not a limitation of this tool.
Reading Your Result
The four outcomes you can get from this tool, and what each one actually tells you.
| Result | What happened | What it means |
|---|---|---|
| Open | The connection completed successfully. | Something is listening on this port and accepting connections. |
| Closed | The connection was actively refused. | Nothing is listening on this port, or it was explicitly rejected. |
| Filtered | No response arrived before the timeout. | A firewall is likely dropping the connection silently — indistinguishable from the host being unreachable. |
| Timeout / No response | Nothing came back within the time allowed. | Common and expected for UDP; for TCP, usually the same cause as “filtered”. |
Reference
A short reference for the ports you’re most likely to check.
| Port | Protocol | Common service | Typical use |
|---|---|---|---|
| 21 | TCP | FTP | File transfer (control connection) |
| 22 | TCP | SSH | Secure remote login and file transfer |
| 25 | TCP | SMTP | Sending email between mail servers |
| 53 | UDP / TCP | DNS | Domain name resolution |
| 80 | TCP | HTTP | Unencrypted web traffic |
| 123 | UDP | NTP | Clock synchronization |
| 143 | TCP | IMAP | Receiving and syncing email |
| 443 | TCP | HTTPS | Encrypted web traffic |
| 3306 | TCP | MySQL | Database connections |
| 3389 | TCP | RDP | Windows Remote Desktop |
Why Check A Port
A port checker is a troubleshooting tool, not a scanner — here’s what it’s actually good for.
Confirm whether a service you can’t reach is actually up and accepting traffic, or whether the problem is somewhere in the network path.
Verify that a newly deployed server, API or website is reachable from the public Internet before pointing real traffic at it.
Confirm that a firewall rule you just added or changed is actually letting the traffic you expect through — or correctly blocking it.
See whether a specific application — a database, a mail server, a custom API — is listening and reachable on its expected port.
Rule out whether a site outage is caused by the web server itself, DNS pointing elsewhere, or a network/firewall issue in between.
Confirm that SSH, RDP or another remote-access port is open before you try to connect from off-site, instead of troubleshooting blind.
Troubleshooting
If a port you expect to be open shows closed or filtered, one of these is the usual reason.
Fix
Only open a port when you actually need to expose that service — every open port is something to keep patched and monitored.
Make sure the service you want to reach is actually installed, running, and configured to listen on the port you expect.
Check the firewall on the server or device itself, and add a rule allowing inbound traffic on that port if it’s missing.
If the device sits behind a router, set up port forwarding for that port to the device’s local IP address.
Confirm you’re forwarding to the correct local IP — it can change if the device uses a dynamic address.
Run the check above again from this page to confirm the port is now reachable from outside your network.
Keep Diagnosing
A port checker confirms accessibility. These tools look at the rest of your connection.
Measure the response time between your device and our test server.
ResultRound-trip time in ms
Check the delay between sending a request and getting a response back.
ResultDelay in ms
Check DNS records for any domain.
ResultA, AAAA, MX, TXT, NS & CNAME records
See the registration details of a domain name.
ResultRegistrar, creation & expiry dates
Find your public IP address instantly.
ResultPublic IPv4 / IPv6 address
Check your download speed, upload speed and connection latency.
ResultDownload & upload in Mbps, ping in ms
A port checker, a ping test and a DNS lookup answer different questions. Ping tells you how quickly a host responds and whether it responds to ICMP at all — it says nothing about any specific port or service. DNS Lookup tells you where a domain currently points. A WHOIS Lookup tells you who registered a domain and when. Port Checker is the one that tells you whether a specific service on a specific port is actually reachable — often the most useful of the four once you know a host is up and pointing at the right place.
FAQ
Short answers to the questions people ask most about checking ports.
A port checker is a tool that tests whether a specific TCP or UDP port on a host or IP address accepts a connection. It is used to confirm that a server, game or service is reachable from the Internet, or to troubleshoot why it isn’t.
Enter the hostname or IP address you want to test, the port number, and the protocol (TCP or UDP), then run the check above. This tool attempts a real connection from our server and reports whether the port is open, closed, or gave no response.
Find your public IP with our What Is My IP tool, forward or open the port on your router if needed, then enter that IP address and port above. Because the check runs from our server rather than your own device, it shows you the same view of your connection that the rest of the Internet has.
An open port means something on that host accepted the connection attempt — a service is running and listening on that port, and it is reachable from wherever the check ran. It doesn’t say anything about whether that service is configured correctly or secure.
A closed port means the host actively refused the connection: nothing is listening on that port, or something on the way explicitly rejected it. This is different from a timeout, where the connection attempt gets no response at all.
A timeout (shown here as “filtered / no response”) means no reply arrived before the check gave up. It almost always means a firewall is silently dropping the connection rather than rejecting it outright — from the outside, that looks identical to the host being offline, so this result is reported as inconclusive rather than as closed.
TCP sets up a connection and confirms delivery, so a port checker gets a clear open or closed answer. UDP sends data with no handshake and no guaranteed reply, so a UDP port checker often can’t tell open from filtered — see TCP vs. UDP Ports above for the full explanation.
You can check any port from 1 to 65535, on any public host or IP address. This tool only connects to public, Internet-routable addresses, so private or internal IP ranges (like 192.168.x.x or 10.x.x.x) can’t be tested this way — check those directly from a device on that same network instead.
Yes, and it’s one of the most common reasons people reach for a tool like this. A service can be listening correctly on your machine or local network while still being unreachable from the wider Internet, usually because of a router or firewall that hasn’t been configured to forward or allow that port. Checking from an external server, as this tool does, is the only way to see what the rest of the Internet actually sees.
Port 80 carries unencrypted HTTP traffic. It shows closed or filtered when no web server is running on that port, a firewall is blocking it, or the site only serves traffic over HTTPS on port 443 instead — increasingly the default for modern web servers.
Port 443 carries encrypted HTTPS traffic. It typically shows closed or filtered when no web server is listening on that port, the firewall or hosting provider is blocking inbound connections to it, or DNS is pointing at the wrong server entirely — worth double-checking with a DNS Lookup first.
Get started
Run the free port checker above to see whether a TCP or UDP port is open and reachable right now.