Port990— FTPS (FTP over TLS, implicit)
TCP 990 is implicit-mode FTPS: the TLS handshake begins the moment the client connects, with no AUTH TLS negotiation. The explicit variant (port 21 + AUTH TLS) is more common today, but many older clients and appliances still default to 990.
Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.
Configuration and troubleshooting
For FTPS on 990: vsftpd needs `listen_port=990` and `implicit_ssl=YES`; FileZilla clients choose "Require implicit FTP over TLS". The control channel uses 990 but data channels take dynamic ports — open the `pasv_min_port`..`pasv_max_port` range in the firewall. Incomplete certificate chains fail silently on some clients; verify with `openssl s_client -connect host:990`.
Important limitations
Implicit FTPS on 990 is less common in modern deployments; IANA formally assigned the FTPS service name for this port. New deployments should use explicit FTPS (21 + AUTH TLS) or SFTP (22, SSH-based). Never mix the three — port, protocol and client settings must all match.
Read-only checks: run on the server host
Choose the commands for your OS. Check TCP and UDP separately. No result is not a lasting availability guarantee; inspect host and container separately.
Linux
sudo ss -ltnp 'sport = :990'macOS
sudo lsof -nP -iTCP:990 -sTCP:LISTENWindows PowerShell
Get-NetTCPConnection -LocalPort 990 -State ListenSources and review
Sources checked on:
This review covers the explanations and sources on this page, not your device or every community software entry below.
Software Using This Port (2 software)
Community software entries: links are references, not individual verification.
FTPS Implicit SSL
FTP over SSL/TLSEncryption
Usage Suggestions
- Before using port 990, please confirm it is not occupied by other services
- If you encounter port conflicts, consider using other ports or stopping the occupying service
Frequently asked questions
What is port 990 used for?
Port 990 sits in the File Sharing category. This page lists the registered purpose and the software commonly associated with it; to see what is actually listening on a specific machine, check the process with ss/netstat.
Is port 990 TCP or UDP?
The registered protocol on this page is TCP. The same number behaves independently on each protocol: TCP may be listening while UDP is idle, so check them separately.
How do I check if port 990 is in use?
On Linux: sudo ss -tlnp 'sport = :990' for an exact port match. On macOS: sudo lsof -nP -iTCP:990 -sTCP:LISTEN. On Windows PowerShell: Get-NetTCPConnection -LocalPort 990 -State Listen. A listener counts as confirmed only when you can see the bind address and process name; without root/admin you will not see other users' processes.
Is port 990 secure? Should I open it in my firewall?
A port number has no inherent security — it depends on whether the listening service is correctly configured and whether it needs exposure at all. Keep loopback/internal-only services firewalled; where public access is required, pair it with source restrictions, VPN or authentication. The caution section on this page lists port-specific risks.
Quick Info
- Port
- 990
- Protocol
- TCP
- Categories
- File Sharing
- Usage Status
- 2 software in use
Related Ports
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