Samba's implementation of SMB3 encryption represents a significant security improvement over previous versions. When configured with smb encrypt = required in the [global] section, it enforces encryption for all connections, preventing downgrade attacks.

SMB3 supports multiple encryption ciphers:

• AES-128-CCM (default in Samba 4.7+)
• AES-128-GCM (more efficient but requires newer clients)

The encryption covers both file data and metadata, providing comprehensive protection.

For secure remote access, combine SMB encryption with other security measures:

[global]
    workgroup = WORKGROUP
    server min protocol = SMB3_11
    server max protocol = SMB3
    encrypt passwords = yes
    smb encrypt = required
    hosts allow = 192.168.1.0/24  # Restrict to local network
    interfaces = eth0 192.168.1.100/24
    bind interfaces only = yes

While SMB3 encryption is strong, exposing Samba directly to the internet isn't recommended due to:

• Potential vulnerabilities in SMB implementation
• Brute force attacks against user accounts
• Limited protection against zero-day exploits

For remote access, consider these more secure approaches:

# Option 1: VPN + Samba
# Set up OpenVPN for secure tunnel:
sudo apt install openvpn
sudo systemctl enable openvpn@server

# Option 2: SSHFS
# Mount remote share securely:
sshfs user@samba-server:/remote/share /local/mount -o allow_other,default_permissions

Verify your encryption is working with this command:

smbclient -L //localhost -U username -m SMB3
# Look for "encryption=on" in the output

SMB3 encryption adds minimal overhead (typically 5-15% throughput reduction) thanks to AES-NI hardware acceleration in modern CPUs.

Regular maintenance is crucial:

# Update regularly
sudo apt update && sudo apt upgrade samba -y

# Monitor logs for suspicious activity
sudo tail -f /var/log/samba/log.*

Since its introduction in SMB 3.0 (Windows 8/Server 2012 era), the protocol has incorporated AES-128/256 encryption capabilities that fundamentally changed its security posture. The older vulnerabilities (like those exploited by WannaCry) primarily affected SMB1, which should never be used today.

The settings you've implemented represent a strong baseline:

[global]
workgroup = workgroup
security = user
encrypt passwords = true
smb encrypt = required  # Forces AES-128-GCM encryption

Key security aspects this enables:

• End-to-end encryption for all traffic
• Protection against credential interception
• Mitigation of man-in-the-middle attacks

While SMB3 encryption is robust, exposing it directly to the internet isn't recommended due to:

• Potential zero-day vulnerabilities
• Brute force attack surface
• Protocol-specific attack vectors

Instead, consider these safer alternatives:

# Option 1: VPN + Samba
sudo apt install openvpn
# Configure OpenVPN with TLS 1.3 and AES-256-GCM

# Option 2: SSH Tunnel
ssh -L 445:localhost:445 user@samba-server -N -f

# Option 3: WebDAV over HTTPS
sudo a2enmod ssl
sudo apt install mod-encoding

For maximum protection, add these to your smb.conf:

[global]
# Protocol restrictions
min protocol = SMB3_11
server max protocol = SMB3

# Authentication hardening
ntlm auth = no
lanman auth = no

# Connection limits
max log size = 10000
max smbd processes = 1000

AES-256-GCM encryption (set via smb encrypt = required) typically causes only 5-15% throughput reduction on modern CPUs with AES-NI instructions. Benchmark with:

# On Linux client:
smbclient -U user //server/share -c "ls" --option="client max protocol=SMB3"

# Measure encrypted transfer:
dd if=/dev/zero bs=1M count=1000 | smbclient -U user //server/share -c "put - largefile.bin"

Essential commands for security monitoring:

# Check active encrypted sessions:
sudo smbstatus -v | grep -i encrypted

# Audit log analysis (look for failed auths):
sudo journalctl -u smbd --since "1 hour ago" | grep -i fail

# Verify protocol versions in use:
sudo tcpdump -i eth0 'port 445' -vv -X | grep -i dialect