# SFTP (SSH File Transfer Protocol)

URL: https://softwaredictionary.org/terms/sftp
Category: Networking
Last updated: 2026-10-06
Pronunciation: es-ef-tee-PEE

In short: SFTP (SSH File Transfer Protocol) is a protocol for securely uploading, downloading and managing files on a remote server over an encrypted SSH connection.

## What is SFTP?

SFTP, the SSH File Transfer Protocol, moves files between computers inside an SSH connection, so logins, commands and file contents are all encrypted. It is often expanded as Secure File Transfer Protocol, but the official name refers to SSH. It runs as a subsystem of SSH on the same TCP port, `22`, and uses the same logins: a password or, preferably, an SSH key.

Besides uploads and downloads, SFTP can list directories, rename, move and delete files, change permissions and resume interrupted transfers, so it works like a remote file system. The protocol was designed by an IETF working group but never finished as an RFC; nearly every implementation, including OpenSSH, uses version 3, described in a draft from 2001. Common clients include the `sftp` command, FileZilla and WinSCP, and libraries exist for every major language.

SFTP is a standard way for companies to exchange files in bulk: banks, payroll providers and retailers drop CSV and XML files on each other's SFTP servers every night. It's like a secure mailroom where every visitor shows ID at the door and every package travels in a locked case. Administrators often restrict SFTP-only users to a single folder with no shell access, and cloud providers offer managed SFTP servers that store the files in object storage.

SFTP is often confused with FTPS and with FTP itself. FTP, the original File Transfer Protocol, sends passwords and data in plain text over separate control and data connections, and FTPS is that same FTP encrypted with TLS and certificates. SFTP is not FTP at all, but a different protocol built on SSH that uses a single connection. It also differs from `scp`, which only copies files, although since OpenSSH 9.0 in 2022, the `scp` command uses the SFTP protocol under the hood.

## Key takeaways

- SFTP transfers and manages files over an encrypted SSH connection.
- It uses SSH's port `22` and SSH logins, including key-based authentication.
- It can list, rename, delete and resume, not only upload and download.
- FTPS is FTP over TLS; SFTP is a separate protocol built on SSH.
- It is widely used for automated file exchange between companies.

## Example: Uploading and downloading with the sftp command

```bash
# Open a session with the same login and keys as SSH (port 22)
sftp deploy@files.example.com

sftp> ls /incoming                 # list a remote folder
sftp> put report.csv /incoming/    # upload
sftp> get /outgoing/invoice.pdf    # download
sftp> rename /incoming/report.csv /incoming/report-2026-10.csv
sftp> bye

# Automated: run commands from a file, e.g. in a nightly cron job
sftp -b upload-batch.txt deploy@files.example.com
```

## Frequently asked questions

**What is the difference between SFTP and FTPS?**

FTPS is the old FTP protocol wrapped in TLS encryption, with certificates and separate connections for commands and data. SFTP is a different protocol that runs inside SSH over a single connection and uses SSH keys or passwords.

**What port does SFTP use?**

SFTP uses the SSH port, TCP `22`, by default, because it runs inside an SSH connection. Plain FTP uses port `21`, and FTPS uses `21` or `990`.

**Is SFTP the same as SCP?**

Both copy files over SSH, but `scp` only copies, while SFTP can also list, rename, delete and resume. Since OpenSSH 9.0, the `scp` command itself uses the SFTP protocol by default.

## Sources

- [IETF draft: SSH File Transfer Protocol (draft-ietf-secsh-filexfer-02)](https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-02)
- [OpenBSD manual: sftp(1)](https://man.openbsd.org/sftp)

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