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[ Linux Command Encyclopedia](#) * * * ## What is sftp? SFTP (SSH File Transfer Protocol) is a secure file transfer protocol that transfers files through an SSH (Secure Shell) encrypted channel. Unlike traditional FTP, SFTP provides higher security, and all transmitted data is encrypted. ### Differences Between SFTP and FTP | Feature | SFTP | FTP | | --- | --- | --- | | Security | Encrypted transmission | Plain text transmission | | Port | 22 (SSH port) | 21 (control port) + 20 (data port) | | Protocol | Based on SSH | Independent protocol | | Firewall friendly | Only one port needs to be open | Multiple ports need to be open | * * * ## sftp Command Basic Syntax sftp [username@]hostname[:path] ### Common Option Parameters | Option | Description | | --- | --- | | `-P port` | Specify connection port (default 22) | | `-b batchfile` | Execute commands in batch file | | `-r` | Recursively copy entire directory | | `-v` | Show detailed debug information | | `-i private_key_file` | Authenticate using specified private key file | * * * ## Connecting to SFTP Server ### Basic Connection Method ## Example sftp username@hostname Example: ## Example sftp user@example.com ### Connecting with Specified Port If the server uses a non-standard port (not 22): ## Example sftp -P 2222 user@example.com ### Using Key Authentication ## Example sftp -i ~/.ssh/id_rsa user@example.com * * * ## Common SFTP Operations ### 1. Local File Operations | Command | Description | | --- | --- | | `lls` | List local directory contents | | `lcd` | Change local working directory | | `lmkdir` | Create directory locally | | `lrm` | Delete local file | ### 2. Remote File Operations | Command | Description | | --- | --- | | `ls` | List remote directory contents | | `cd` | Change remote working directory | | `mkdir` | Create directory on remote | | `rm` | Delete remote file | | `rename` | Rename remote file | ### 3. File Transfer | Command | Description | | --- | --- | | `put local_file ` | Upload file to remote server | | `get remote_file ` | Download file from remote server | | `mput local_files*` | Upload multiple files | | `mget remote_files*` | Download multiple files | * * * ## Practical Examples ### Example 1: Upload File to Server ## Example sftp user@example.com sftp>cd/var/www/html sftp> put index.html sftp>exit ### Example 2: Download Entire Directory (Recursive) ## Example sftp -r user@example.com:/backups /local/backups ### Example 3: Using Batch File Create `sftp_commands.txt`: put file1.txt put file2.txt get report.pdf exit Execute batch: ## Example sftp -b sftp_commands.txt user@example.com * * * ## Advanced Tips ### 1. Using Wildcards to Transfer Multiple Files ## Example sftp> mput *.jpg # Upload all jpg files sftp> mget log_*.txt # Download all txt files starting with log_ ### 2. Changing File Permissions ## Example sftp>chmod 644 index.html ### 3. Viewing File Information ## Example sftp>ls-l ### 4. Using Symbolic Links ## Example sftp> symlink /path/to/original /path/to/link * * * ## Troubleshooting Common Issues ### 1. Connection Refused * Check if the server is running SSH service * Confirm if the port is correct * Check firewall settings ### 2. Authentication Failed * Confirm username and password are correct * Check key file permissions (should be 600) * Ensure your public key is on the server ### 3. File Transfer Interrupted * Check network connection * Try using `reget` and `reput` commands to resume transfer ### 4. Insufficient Permissions * Check write permissions on remote directory * May need to use `sudo` (but sftp usually doesn't support direct sudo) * * * ## Security Best Practices 1. **Use key authentication** instead of password authentication 2. **Limit user permissions**, use chroot environment 3. **Regularly update** SSH server software 4. **Disable root login**, use regular user + sudo 5. **Monitor log files** (/var/log/auth.log) * * * ## Summary SFTP is an important tool for securely transferring files in Linux systems. Through this guide, you should have mastered: * Basic concepts and connection methods of SFTP * Common file operations and transfer commands * Practical batch processing and advanced tips * Solutions to common problems * Best practices for secure usage Now you can safely and efficiently transfer files between local and remote servers! [ Linux Command Encyclopedia](#)