SCP - Secure Copy¶

Overview¶

SCP (Secure Copy Protocol) copies files between hosts over SSH. Simple, secure, and available wherever SSH is.

┌──────────────────────────────────────────────────────────────────────────┐
│                           SCP Transfer                                    │
│                                                                           │
│   Local Machine                              Remote Server                │
│   ┌─────────────────┐                       ┌─────────────────┐          │
│   │                 │      SSH Tunnel       │                 │          │
│   │   file.txt     ─┼──────────────────────>│    file.txt     │          │
│   │                 │      Encrypted        │                 │          │
│   └─────────────────┘                       └─────────────────┘          │
│                                                                           │
└──────────────────────────────────────────────────────────────────────────┘

Basic Syntax¶

scp [options] source destination

Locations can be: - Local: /path/to/file - Remote: user@host:/path/to/file

Copy To Remote¶

Single File¶

scp file.txt user@host:/home/user/
scp file.txt user@host:~/
scp file.txt user@host:~/newname.txt

Multiple Files¶

scp file1.txt file2.txt user@host:~/
scp *.txt user@host:~/documents/

Directory¶

scp -r directory/ user@host:~/
scp -r directory/ user@host:~/newdirname/

Copy From Remote¶

Single File¶

scp user@host:/path/to/file.txt ./
scp user@host:~/file.txt ./local_name.txt

Multiple Files¶

scp user@host:~/file1.txt user@host:~/file2.txt ./
scp "user@host:~/*.txt" ./

Directory¶

scp -r user@host:~/directory/ ./

Copy Between Remote Hosts¶

scp user1@host1:/path/file.txt user2@host2:/path/

Routing

By default, traffic goes through your local machine. Use -3 to force this, or configure ProxyJump for direct transfer.

Common Options¶

Port¶

scp -P 2222 file.txt user@host:~/

Identity File¶

scp -i ~/.ssh/mykey file.txt user@host:~/

Recursive (Directories)¶

scp -r directory/ user@host:~/

Preserve Attributes¶

scp -p file.txt user@host:~/
# Preserves modification times, access times, modes

Compression¶

scp -C largefile.tar.gz user@host:~/

Bandwidth Limit¶

scp -l 1000 file.txt user@host:~/
# Limit in Kbit/s (1000 Kbit/s = ~125 KB/s)

Quiet Mode¶

scp -q file.txt user@host:~/

Verbose¶

scp -v file.txt user@host:~/

Using SSH Config¶

SCP uses ~/.ssh/config:

# ~/.ssh/config
Host myserver
    HostName server.example.com
    User admin
    IdentityFile ~/.ssh/server_key
    Port 2222

Then simply:

scp file.txt myserver:~/
scp myserver:~/file.txt ./

Through Jump Host¶

With ProxyJump¶

scp -o ProxyJump=bastion file.txt internal:~/

Using Config¶

# ~/.ssh/config
Host internal
    HostName 10.0.0.10
    User admin
    ProxyJump bastion

scp file.txt internal:~/

Progress and Statistics¶

Show Progress (Default)¶

scp file.txt user@host:~/
# Shows: file.txt    100%  1234KB  10.5MB/s   00:00

Hide Progress¶

scp -q file.txt user@host:~/

Handling Special Characters¶

Spaces in Paths¶

# Quote the entire remote path
scp "user@host:~/path with spaces/file.txt" ./

# Or escape
scp user@host:~/path\ with\ spaces/file.txt ./

Special Characters¶

scp "user@host:~/file[1].txt" ./
scp user@host:"~/file[1].txt" ./

Large File Transfers¶

With Compression¶

scp -C largefile.iso user@host:~/

Resumable (Not Native)¶

SCP doesn't support resume. For large files, use rsync instead:

rsync -avP --partial largefile.iso user@host:~/

Monitor Progress with pv¶

# Alternative approach
cat largefile.iso | pv | ssh user@host "cat > largefile.iso"

Batch Operations¶

Multiple Hosts¶

for host in server1 server2 server3; do
    scp file.txt user@$host:~/
done

Multiple Files with Wildcards¶

scp user@host:"/var/log/*.log" ./logs/

From File List¶

while read file; do
    scp "$file" user@host:~/backup/
done < filelist.txt

Exit Codes¶

Code	Meaning
0	Success
1	General error
2	Connection error
65	Host not allowed
66	Protocol error

Comparison with Alternatives¶

Feature	SCP	SFTP	rsync
Simple copies	Yes	Yes	Yes
Interactive	No	Yes	No
Resume transfers	No	Yes	Yes
Delta sync	No	No	Yes
Preserve permissions	Yes	Yes	Yes
Bandwidth limit	Yes	Yes	Yes
Available everywhere	Yes	Yes	Usually (needs separate install on some systems)

When to Use SCP¶

Use SCP for: - Quick, simple file copies - Small to medium files - One-off transfers - Scripts needing simple syntax

Use SFTP for: - Interactive file management - Browsing remote directories - Resume support

Use rsync for: - Large files (resume support) - Directory synchronization - Incremental backups - Bandwidth optimization

Troubleshooting¶

Permission Denied¶

# Check remote permissions
ssh user@host "ls -la ~/target/"

# Check you're using correct user
scp file.txt correctuser@host:~/

Connection Refused¶

# Test SSH connection first
ssh user@host

# Check port
scp -P 2222 file.txt user@host:~/

Slow Transfers¶

# Enable compression
scp -C file.txt user@host:~/

# Check network
ssh user@host "speedtest-cli"

Path Issues¶

# Use absolute paths
scp file.txt user@host:/home/user/

# Quote paths with spaces
scp file.txt "user@host:/path with spaces/"

Security Considerations¶

Uses SSH encryption - Traffic is secure
Respects SSH config - Same security as SSH
Key-based auth - Use keys, not passwords
Verify host keys - Don't skip host key verification

# Bad (skips verification)
scp -o StrictHostKeyChecking=no file.txt user@host:~/

# Good (uses verification)
scp file.txt user@host:~/