sftp Command Linux: Complete Guide to Secure File Transfer Protocol

The sftp command (Secure File Transfer Protocol) is a powerful Linux utility that provides secure file transfer capabilities over an encrypted SSH connection. Unlike traditional FTP, SFTP ensures data integrity and confidentiality by encrypting all communications between client and server.

What is SFTP?

SFTP is a network protocol that combines the reliability of SSH with file transfer functionality. It operates on port 22 by default and provides:

• Encryption: All data transfers are encrypted end-to-end
• Authentication: Multiple authentication methods including password and key-based
• Integrity: Data corruption detection and prevention
• Firewall-friendly: Uses a single port for all operations

Basic SFTP Syntax

The basic syntax for the sftp command is:

sftp [options] [user@]hostname[:directory]

Common SFTP Options

Connecting to SFTP Server

Basic Connection

Connect to an SFTP server using username and password:

$ sftp [email protected]
[email protected]'s password: 
Connected to example.com.
sftp>

Connection with Custom Port

$ sftp -P 2222 [email protected]
Connected to example.com.
sftp>

Key-Based Authentication

$ sftp -i ~/.ssh/private_key [email protected]
Connected to example.com.
sftp>

Essential SFTP Commands

Navigation Commands

pwd – Print Working Directory

sftp> pwd
Remote working directory: /home/user

lpwd – Local Print Working Directory

sftp> lpwd
Local working directory: /home/localuser

ls – List Remote Directory

sftp> ls
documents    downloads    pictures    videos
file1.txt    file2.pdf    script.sh

lls – List Local Directory

sftp> lls
Desktop  Documents  Downloads  Music  Pictures  Videos

cd – Change Remote Directory

sftp> cd documents
sftp> pwd
Remote working directory: /home/user/documents

lcd – Change Local Directory

sftp> lcd /tmp
sftp> lpwd
Local working directory: /tmp

File Transfer Commands

get – Download Files from Server

Download a single file:

sftp> get file1.txt
Fetching /home/user/file1.txt to file1.txt
/home/user/file1.txt                    100%  1024    1.2KB/s   00:01

Download with different local name:

sftp> get remote_file.txt local_file.txt

Download multiple files using wildcards:

sftp> get *.txt
Fetching /home/user/file1.txt to file1.txt
Fetching /home/user/file2.txt to file2.txt

put – Upload Files to Server

Upload a single file:

sftp> put local_file.txt
Uploading local_file.txt to /home/user/local_file.txt
local_file.txt                          100%  2048    2.1KB/s   00:01

Upload with different remote name:

sftp> put local_file.txt remote_file.txt

Upload multiple files:

sftp> put *.pdf
Uploading document1.pdf to /home/user/document1.pdf
Uploading document2.pdf to /home/user/document2.pdf

mget – Download Multiple Files

sftp> mget *.log
Fetching /home/user/app1.log to app1.log
Fetching /home/user/app2.log to app2.log
Fetching /home/user/error.log to error.log

mput – Upload Multiple Files

sftp> mput *.jpg
Uploading photo1.jpg to /home/user/photo1.jpg
Uploading photo2.jpg to /home/user/photo2.jpg

Directory Operations

mkdir – Create Remote Directory

sftp> mkdir backup
sftp> ls
backup       documents    downloads

lmkdir – Create Local Directory

sftp> lmkdir temp_folder

rmdir – Remove Remote Directory

sftp> rmdir old_folder

rename – Rename Remote File/Directory

sftp> rename old_name.txt new_name.txt

rm – Remove Remote File

sftp> rm unwanted_file.txt

Advanced SFTP Features

Recursive Directory Transfer

Download entire directory structure:

sftp> get -r remote_directory
Fetching /home/user/remote_directory/ to remote_directory/
Entering /home/user/remote_directory/
Fetching /home/user/remote_directory/file1.txt to remote_directory/file1.txt
Fetching /home/user/remote_directory/subfolder/ to remote_directory/subfolder/

Upload entire directory structure:

sftp> put -r local_directory

File Permissions and Attributes

chmod – Change Remote File Permissions

sftp> chmod 755 script.sh
Changing mode on /home/user/script.sh

chown – Change Remote File Ownership

sftp> chown user:group file.txt

ls -la – Detailed File Listing

sftp> ls -la
drwxr-xr-x    3 user     group        4096 Aug 25 10:30 .
drwxr-xr-x    5 user     group        4096 Aug 24 15:20 ..
-rw-r--r--    1 user     group        1024 Aug 25 09:15 file1.txt
-rwxr-xr-x    1 user     group        2048 Aug 25 10:25 script.sh

Progress and Resume

Enabling Progress Indicators

sftp> progress
Progress meter enabled

Resume Interrupted Transfers

sftp> reget partially_downloaded_file.zip

SFTP Configuration and Customization

SSH Configuration File

Create or edit ~/.ssh/config for easier connections:

Host myserver
    HostName example.com
    User myusername
    Port 2222
    IdentityFile ~/.ssh/myserver_key

Then connect simply with:

$ sftp myserver

Batch Mode Operations

Create a batch file sftp_commands.txt:

cd /remote/directory
lcd /local/directory
get *.txt
put backup.tar.gz
quit

Execute batch commands:

$ sftp -b sftp_commands.txt [email protected]

Security Best Practices

Key-Based Authentication Setup

Generate SSH key pair:

$ ssh-keygen -t rsa -b 4096 -f ~/.ssh/sftp_key

Copy public key to server:

$ ssh-copy-id -i ~/.ssh/sftp_key.pub [email protected]

Restricting SFTP Access

Configure SSH server to restrict users to SFTP-only access by editing /etc/ssh/sshd_config:

Match User sftpuser
    ChrootDirectory /home/sftpuser
    ForceCommand internal-sftp
    AllowTcpForwarding no
    X11Forwarding no

Troubleshooting Common Issues

Connection Refused

Check if SSH service is running:

$ systemctl status ssh

Verify correct port:

$ nmap -p 22 example.com

Permission Denied

Check SSH key permissions:

$ chmod 600 ~/.ssh/private_key
$ chmod 644 ~/.ssh/private_key.pub

Verbose Debugging

Use verbose mode for detailed connection information:

$ sftp -v [email protected]

Performance Optimization

Compression

Enable compression for better performance over slow connections:

$ sftp -C [email protected]

Parallel Transfers

Use multiple connections for faster transfers:

$ sftp -o "ControlMaster=auto" -o "ControlPath=/tmp/ssh-%r@%h:%p" [email protected]

Alternative SFTP Tools

lftp

A more feature-rich alternative:

$ lftp sftp://[email protected]

rsync over SSH

For synchronization tasks:

$ rsync -avz -e ssh source/ [email protected]:/destination/

Conclusion

The sftp command is an essential tool for secure file transfers in Linux environments. Its integration with SSH provides robust security while maintaining ease of use. Whether you’re managing servers, backing up data, or transferring files between systems, mastering SFTP commands will significantly enhance your Linux administration skills.

Remember to always use key-based authentication when possible, keep your systems updated, and follow security best practices to maintain a secure file transfer environment.