FTP Port Checker — Is Your Server's Port Open?

Enter a host and a port and this tool tells you whether the port accepts connections — from our servers, in a few seconds. Check the usual FTP and SFTP ports (21, 22, 990, 2121) or any port from 1–65535. Fast, rate-limited, and only the host and port you type are ever sent.

Connect Now — transfer files from your browser

Why check a port before you connect?

Most FTP and SFTP connection problems are boring and mechanical: the wrong port, the server moved, or a firewall blocking the way. A port check turns that guessing into a single answer — can anything reach this port on this host at all? If the answer is no, no client will connect either, and you can skip straight to checking your server's firewall and port forwarding. If the answer is yes, you know the path is open and the problem (if there is one) is further up — in the service itself or your login.

How this port checker works

The check runs from our servers, not from your computer. Your browser sends the host and port to the FilePort Pro API, and the server attempts a plain TCP connection to that host and port with a five-second timeout. TCP is the transport both FTP and SFTP run on, so a successful handshake is a reliable sign the network path is open. The result is one of four states: open (the host accepted the connection), closed (the host refused it), filtered (no reply — a firewall is probably dropping the packets), or unreachable (the host could not be found or routed to). Only that outcome — plus the time the open handshake took — comes back to your browser.

Honest notes: what a "port open" result does and doesn't mean

An open port is not the same as a working FTP or SFTP server. The probe only completes a TCP handshake — it does not speak FTP or SFTP, and it does not try to log in. A port can be open for a completely different service, or a server can accept connections and still reject your username or password once you talk to it. And because results come from our servers, they measure the path between our network and your host — a port can look open from here but be unreachable from your specific network (for example, a firewall that only allows certain source IPs). That is exactly why the tool is honest about what it checks: reachability, not your login.

What FTP port 21 actually does — and what it doesn't

FTP is unusual because it uses two connections, not one. Port 21 is the command (control) connection — the one that carries your login and every instruction ("list this folder", "get this file", "put this file"). The actual file data travels over a separate data connection on a different port, negotiated at the time of each transfer. This checker probes port 21, which is the right first thing to check: if the control connection is unreachable, no FTP client can talk to the server at all. But a good result on 21 only proves the control path is open — it doesn't prove the data path is.

Port 21 vs port 22: FTP vs SFTP

These two ports are easy to mix up. Port 21 is the plain-FTP control port: classic FTP sends your username and password in the clear (unencrypted). Port 22 is SFTP/SSH, which encrypts everything — your login and your files. A server can offer FTP and SFTP, only one of them, or neither. Before you probe, know which one your host provides: SFTP is almost always the safer choice because it's encrypted end to end. If you're unsure which your host supports, check its control panel or documentation.

Active vs passive FTP: which port the data uses

Because FTP splits control and data into two connections, the data connection can use different ports depending on the mode. In active mode, the server opens a connection back to your computer on a high port. In passive mode — the default in most modern clients and in web browsers — the client connects to a high port that the server advertises. Passive mode needs the server to allow a range of high ports through its firewall. This is why a common symptom is "port 21 looks fine but transfers hang": the control connection on 21 works, but the data connection is blocked. A port check on 21 alone can't reveal that — it only tells you the control path is open.

Why "FTP port" means TCP, not UDP

FTP runs on TCP, and TCP is what this checker probes. TCP is the reliable transport that guarantees data arrives intact and in order — exactly what file transfer needs, so port 21 is always checked as a TCP port. If you've seen the query "ftp port udp", the honest answer is that FTP does not use UDP. UDP is for a different class of service — like DNS (port 53) or live video — where a little packet loss is acceptable. A UDP scan of port 21 is therefore not the right check for FTP; this tool checks TCP, which is what FTP and SFTP actually use.

Why a port shows as closed

A "closed" result means the host answered and refused the connection, or nothing is listening there. Common causes: the FTP/SFTP service isn't running on that port, the server's firewall is rejecting the connection, the host provider blocks inbound traffic on that port, or you're testing the wrong IP or port. A "filtered" result (a timeout) usually means a firewall is silently dropping the packets, and "unreachable" means the host couldn't be found or routed to. For FTP specifically, keep in mind that port 21 being open doesn't guarantee the data ports are — a passive-mode config can still fail in the middle of a transfer.

How to troubleshoot a closed FTP port

Start by double-checking that you're testing the right host and port — a mistyped IP or a wrong port is the most common cause. If the port really is closed, look at your host's firewall or, on a cloud server, its security group inbound rules. For example, our AWS EC2 SFTP guide shows how to open TCP port 22 in a security group. Then confirm whether your host actually offers FTP on port 21 or SFTP on port 22, since many modern hosts provide only SFTP. If the port is open but a real login still fails, the problem is in the service or your credentials — test that with the SFTP Connection Tester, or just try transferring in your browser with the web FTP client. Full guide: FTP connection errors — what "refused," "timed out," and 530 mean and how to fix each one.

Frequently asked questions

What does it mean for a port to be open?

An open result means our server completed a TCP connection to that port on the host — something on the other end accepted the connection. It does not mean FTP or SFTP is running there, and it does not mean your login would work; the port could be open for an entirely different service.

What data does this tool collect?

Only the host and port you enter are sent to FilePort Pro's server, which runs the probe — no passwords, no files, and no session. Nothing is stored or retained afterwards: the server logs only an anonymous outcome code (open, closed, filtered or unreachable), never the host or port.

Why does a port show as filtered or time out?

A filtered or timed-out result means the probe sent its connection request but no reply arrived within five seconds. The most common cause is a firewall silently dropping the packets — a common security setting — but it can also mean the host or the network path is temporarily unreachable.

Is FTP the same as SFTP?

No. FTP is the older file-transfer protocol that sends your login and files in the clear on port 21, while SFTP transfers files inside an encrypted SSH connection on port 22. A server can offer one, the other, or both — SFTP is the safer option wherever it's available.

Does FTP use TCP or UDP?

FTP uses TCP, not UDP. Port 21 is a TCP port, and this checker probes it as TCP. UDP is used by different services such as DNS; a UDP scan of port 21 is not the right way to test FTP.

What is passive FTP?

In passive mode, the client connects to a high port the server advertises, which is the default in most FTP clients and browsers. It differs from active mode, where the server connects back to the client. Firewalls that block those data ports are a common reason transfers hang even when port 21 is open.

Port's open? Now do the transfer from your browser

Once you know the port is reachable, connect straight from the browser with FilePort Pro's web SFTP client — no software to install, and your credentials are never stored. Prefer SFTP over plain FTP where you can: FTP sends credentials in the clear, while SFTP is encrypted end to end.

If your server only supports plain FTP, open the free web FTP client instead and connect to port 21 from your browser.

Connect Now — transfer files from your browser

Explore the other free tools: SFTP command generator, transfer time calculator, checksum calculator and the ftp:// URL parser — or see all of them on the tools hub. Want to know exactly how the app handles your data? Read the security page and the privacy policy.