Copying Files Over a Network

SSH-Based Methods

SCP (Secure Copy Protocol)

Traditional and simple file transfer over SSH.

# Copy file to remote host
scp file.txt user@remote-host:/path/to/destination/

# Copy file from remote host
scp user@remote-host:/path/to/file.txt ./local-destination/

# Copy directory recursively
scp -r /local/directory/ user@remote-host:/remote/path/

# Copy with port specification
scp -P 2222 file.txt user@remote-host:/path/

# Copy multiple files
scp file1.txt file2.txt user@remote-host:/path/

SFTP (SSH File Transfer Protocol)

Interactive file transfer with more features than SCP.

# Connect to remote host
sftp user@remote-host

# SFTP commands
sftp> put local-file.txt remote-file.txt    # Upload
sftp> get remote-file.txt local-file.txt    # Download
sftp> put -r local-directory/               # Upload directory
sftp> get -r remote-directory/              # Download directory
sftp> ls                                    # List remote files
sftp> lls                                   # List local files
sftp> cd /remote/path                       # Change remote directory
sftp> lcd /local/path                       # Change local directory

rsync over SSH

Most powerful and efficient for synchronization.

# Basic sync to remote
rsync -avz /local/path/ user@remote-host:/remote/path/

# Sync from remote
rsync -avz user@remote-host:/remote/path/ /local/path/

# Common options
rsync -avz --delete /source/ user@host:/dest/  # Delete extra files
rsync -avz --progress /source/ user@host:/dest/ # Show progress
rsync -avz --exclude='*.tmp' /source/ user@host:/dest/ # Exclude files

# Dry run (test without copying)
rsync -avz --dry-run /source/ user@host:/dest/

Network File Systems

NFS (Network File System)

Mount remote directories as local filesystems.

# Server setup (/etc/exports)
/shared/directory 192.168.1.0/24(rw,sync,no_subtree_check)

# Client mount
sudo mount -t nfs server-ip:/shared/directory /local/mount/point

# Permanent mount (/etc/fstab)
server-ip:/shared/directory /mnt/nfs nfs defaults 0 0

SMB/CIFS (Windows Shares)

Access Windows shares or Samba servers.

# Mount SMB share
sudo mount -t cifs //server-ip/share /mnt/smb -o username=user,password=pass

# Using credentials file
sudo mount -t cifs //server/share /mnt/smb -o credentials=/etc/samba/credentials

# Copy files after mounting
cp /local/files/* /mnt/smb/

HTTP-Based Methods

wget

Download files from web servers.

# Download single file
wget https://example.com/file.zip

# Download with custom filename
wget -O custom-name.zip https://example.com/file.zip

# Download directory recursively
wget -r -np -k https://example.com/directory/

# Resume interrupted download
wget -c https://example.com/large-file.zip

curl

Versatile tool for uploading and downloading.

# Download file
curl -O https://example.com/file.zip

# Upload file via POST
curl -X POST -F "file=@local-file.txt" https://upload.example.com/

# Upload with authentication
curl -u username:password -T file.txt ftp://ftp.example.com/

Modern Transfer Tools

rclone

"rsync for cloud storage" - supports many cloud providers.

# Configure cloud storage
rclone config

# Copy to cloud
rclone copy /local/path remote:bucket/path

# Sync with cloud
rclone sync /local/path remote:bucket/path

# Mount cloud storage
rclone mount remote:bucket /mnt/cloud

Performance Comparison

Method	Speed	Security	Resumable	Compression	Best For
scp	Medium	High	No	No	Simple transfers
sftp	Medium	High	Yes	No	Interactive transfers
rsync	Fast	High	Yes	Yes	Synchronization
wget/curl	Fast	Medium	Yes	No	Web downloads
rclone	Fast	High	Yes	Yes	Cloud storage

Security Considerations

SSH Key Authentication

More secure than passwords for SSH-based transfers.

# Generate SSH key pair
ssh-keygen -t rsa -b 4096

# Copy public key to remote host
ssh-copy-id user@remote-host

# Now SCP/SFTP/rsync work without passwords
scp file.txt user@remote-host:/path/

Encryption in Transit

SSH-based methods (SCP, SFTP, rsync over SSH) - Always encrypted
HTTPS - Encrypted web transfers
Plain FTP/HTTP - Unencrypted, avoid for sensitive data

Best Practices

Use rsync for large transfers - It's resumable and only transfers changes
Compress data - Use -z flag with rsync for slow networks
Test with dry-run - Always test large operations first
Use SSH keys - More secure and convenient than passwords
Monitor progress - Use --progress flag for long transfers
Verify transfers - Use checksums to ensure data integrity

# Example: Secure, efficient backup to remote server
rsync -avz --progress --delete \
  --exclude='*.tmp' --exclude='.cache' \
  /home/user/important-data/ \
  backup-server:/backups/$(date +%Y-%m-%d)/