Port 990: FTPS
Port 990 is the control channel for FTPS, FTP wrapped in implicit TLS. It negotiates the encrypted session before file data moves over port 989, unlike plain FTP on ports 20 and 21.
| Port number | 990 |
|---|---|
| Service | FTPS Protocol (control) |
| Protocol | TCP |
| Category | File transfer |
| Default encryption | Yes (TLS/SSH) |
How do I check whether port 990 is open?
Port 990 carries TCP, so a connection either completes its handshake or it does not, which makes the check definitive.
| Question | Command | What to know |
|---|---|---|
| Is it open on a remote host? | nc -vz example.com 990 | A TCP handshake either completes or it does not, so netcat gives a definitive answer in one line. |
| Same check on Windows | Test-NetConnection example.com -Port 990 | Built into PowerShell. TcpTestSucceeded in the output is the answer; telnet is not installed by default on modern Windows. |
| What is listening locally? | ss -tlnp | grep ':990 ' | Lists the process bound to port 990 on Linux. On macOS use lsof -nP -iTCP:990 -sTCP:LISTEN, on Windows netstat -ano | findstr :990 |
Replace example.com with the host you are testing. A blocked port and a port with nothing listening on it look identical from the outside, so if a service should be running, check locally before blaming the firewall.
Frequently asked questions
What is port 990 used for?
Port 990 is the control channel for FTPS, FTP wrapped in implicit TLS. It negotiates the encrypted session before file data moves over port 989, unlike plain FTP on ports 20 and 21.
Is port 990 TCP or UDP?
Port 990 (FTPS) uses TCP.
Is port 990 secure?
Yes. Port 990 carries encrypted traffic by default, so data in transit is protected.
Should I open port 990 on my firewall?
Only if you specifically need FTPS. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.