SFTP Server Docker Image

A secure, configurable SFTP server in a Docker container for easy file transfers.

Features

• Chroot environment for SFTP users
• Configurable user ID and group ID
• Support for password and public key authentication
• Persistent SSH host keys
• Modern encryption algorithms
• Terrapin attack protection

Quick Start

# Start with password authentication (required)
docker run --name sftp -p 2222:22 -e PASS=your_secure_password -d mobilistics/sftp

# With data volume
docker run --name sftp -p 2222:22 -v /path/on/host:/data/incoming -d mobilistics/sftp

# With persistent SSH keys
docker run --name sftp -p 2222:22 \
  -v /path/on/host/data:/data/incoming \
  -v /path/on/host/ssh:/ssh \
  -d mobilistics/sftp

# With custom user credentials
docker run --name sftp -p 2222:22 \
  -v /path/on/host/data:/data/incoming \
  -e USER=myuser \
  -e PASS=secure_password \
  -d mobilistics/sftp

Configuration Options

Environment Variable	Description	Default	Example
USER	SFTP username	sftp	USER=myuser
PASS	User's password	No default, required if PUBKEY not set	PASS=my_secure_password
USER_ID	UID of the user	1000	USER_ID=1001
GROUP_ID	GID of the group	1000	GROUP_ID=1001
PUBKEY	SSH public key for key-based authentication	-	PUBKEY=ssh-rsa AAAA...

Important: Either PASS or PUBKEY must be specified. For better security, using SSH keys (PUBKEY) is recommended over passwords.

Volume Configuration

The image uses two important volumes:

1. /data/incoming: Directory for file transfers
2. /ssh: Location for SSH host keys (optional, for persistence)

# Example with defined volumes
docker volume create sftp-data
docker volume create sftp-keys

docker run --name sftp -p 2222:22 \
  -v sftp-data:/data/incoming \
  -v sftp-keys:/ssh \
  -d mobilistics/sftp

Connecting to the SFTP Server

Command Line (Linux/macOS/Windows with OpenSSH)

# Connect with password (interactive input)
sftp -P 2222 sftp@localhost

# Connect with private key
sftp -P 2222 -i /path/to/private_key sftp@localhost

Docker Compose Example

version: "3"

services:
  sftp:
    image: mobilistics/sftp
    container_name: sftp-server
    ports:
      - "2222:22"
    volumes:
      - ./data:/data/incoming
      - ./ssh:/ssh
    environment:
      - USER=myuser
      - PASS=my_secure_password
      - USER_ID=1000
      - GROUP_ID=1000
    restart: unless-stopped

Troubleshooting

SSH/SFTP Connection Issues

# Check if the container is running
docker ps | grep sftp

# View container logs
docker logs sftp

# Enter the container for debugging
docker exec -it sftp bash