Use scp on Linux: SSH Ports, Keys and Safe File Copies

The OpenSSH scp command copies files over SSH authentication and transport. Since OpenSSH 9.0 it uses SFTP by default; its historical name does not mean current versions necessarily use the legacy SCP protocol. A server offering FTP alone cannot accept an scp transfer.

Check access and the server identity

Obtain the correct host, SSH port, account, authorized key and permitted directory. Verify a new host-key fingerprint through a trusted separate channel. Stop on an unexpected key change; do not bypass strict checking. Use a transfer account rather than root, and preserve a recovery copy before overwriting a remote file.

Upload and download syntax

These are templates, not connections to a real service. Replace the example host, user and paths only after confirming authorization. Capital -P selects the port; lowercase -p preserves modification/access times and file mode bits.

scp -P 2222 -i ~/.ssh/transfer_ed25519 ./report.txt user@server.example:/upload/report.txt
scp -P 2222 -i ~/.ssh/transfer_ed25519 user@server.example:/upload/report.txt ./downloaded-report.txt

The source comes before the destination. A local name containing a colon can be mistaken for a remote specification; use an explicit local path such as ./name:part. Quote local paths containing spaces and check the installed client’s remote path handling; old SCP and modern SFTP modes have different shell-expansion behavior.

Common options

Option	Meaning and boundary
-r	Copy a directory recursively. OpenSSH scp follows symlinks encountered during traversal, so inspect scope before copying a tree.
-p	Preserve times and mode bits where permitted; not a complete ownership/ACL backup.
-i path	Select an identity file. Keep the private key protected; never upload it into the destination web root.
-F path	Use a specified SSH client configuration file.
-l limit	Limit bandwidth in kilobits per second, not kilobytes.
-4 or -6	Restrict address family when the destination supports it.
-v	Show diagnostics; redact account and infrastructure details before sharing.

-O requests the legacy SCP protocol. It is a compatibility option, not a general security or login-error fix. Do not use it simply to silence a path or subsystem problem without understanding the server requirements.

Verify the result

Check the exit status and compare important file contents or trusted checksums. A progress meter does not prove application-level correctness, and recursive copying does not create a consistent database snapshot or a versioned backup. For multiple operations and directory inspection, use the interactive SFTP client.

Reference: OpenSSH scp manual.

Reviewed October 15, 2026. The port and identity syntax was tested against a disposable loopback SSH service with synthetic files; these example hostnames were not contacted.