Verified diagnostic signature
The FTP control or data connection was rejected by authentication, authorization, or network mode.
Match output from ftp, understand the likely cause, then continue with sourced, read-only checks.
- Confidence
- high
- Platforms
- linux · macos · windows
- Verified
- 2026-07-24
Recognized output
Signature matched locally
425 Can't open data connectionOneLiners matches this pattern in your browser. Your pasted output is not stored or indexed.
Likely causes
What usually produces this signal
- Wrong credentials
- Account or path policy
- Passive data port blocked
- Server-side filesystem access
Safe next checks
Collect evidence before changing the system
Connect to a TCP service and read its banner with netcat
printf '\n' | nc -v -w 5 <host> <port>The output matches the expected target and exits without an error.
List files in a remote FTP directory with curl
curl --fail --show-error --list-only --user <username> ftp://<host>/<remote-path>/The output matches the expected target and exits without an error.