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CIFS/SMB Setup and Configuration for Proxmox

Common Internet File System (CIFS) and Server Message Block (SMB) are network file sharing protocols that enable clients to access files and services on remote servers. This guide provides comprehensive instructions for setting up CIFS/SMB with Proxmox, covering both server and client configuration.

What is CIFS/SMB?​

CIFS/SMB is a network file sharing protocol suite that allows applications to read and write files and request services from server programs in a computer network. Originally developed by Microsoft, it's now widely supported across different operating systems.

Benefits of CIFS/SMB​

  • ✅ Cross-Platform: Excellent Windows compatibility, good Linux support
  • ✅ Built-in Authentication: Integrated with Active Directory and domain authentication
  • ✅ Feature Rich: Advanced features like file locking, permissions, and metadata
  • ✅ Mature Protocol: Well-established with extensive enterprise support
  • ✅ Encryption: Modern SMB versions support encryption
  • ✅ Wide Adoption: Supported by most NAS devices and storage systems

Limitations of CIFS/SMB​

  • ❌ Performance Overhead: Higher protocol overhead compared to NFS
  • ❌ Complexity: More complex configuration than simpler protocols
  • ❌ Windows Dependency: Best performance and features with Windows servers
  • ❌ Version Compatibility: Different SMB versions have varying capabilities

SMB/CIFS Versions Comparison​

SMB 3.x (Modern - Recommended)

  • Security: End-to-end encryption, secure negotiation
  • Performance: Improved throughput, multichannel support
  • Features: Scale-out file servers, transparent failover
  • Resilience: Continuous availability, automatic recovery
  • Compatibility: Windows 8+, Windows Server 2012+, modern Linux
  • Recommendation: Use for all new deployments

Architecture Overview​

┌─────────────────────────────────────────────────────────────┐
│                 Proxmox Cluster                             │
│                                                             │
│  ┌─────────────┐    ┌─────────────┐    ┌─────────────┐     │
│  │ Proxmox     │    │ Proxmox     │    │ Proxmox     │     │
│  │ Node 1      │    │ Node 2      │    │ Node 3      │     │
│  │             │    │             │    │             │     │
│  │ CIFS Client │    │ CIFS Client │    │ CIFS Client │     │
│  │ /mnt/pve/   │    │ /mnt/pve/   │    │ /mnt/pve/   │     │
│  │ └─smb-share │    │ └─smb-share │    │ └─smb-share │     │
│  └─────────────┘    └─────────────┘    └─────────────┘     │
│         │                   │                   │          │
└─────────┼───────────────────┼───────────────────┼──────────┘
          │                   │                   │
          └───────────────────┼───────────────────┘
                              │
                    ┌─────────┴─────────┐
                    │   Network Switch  │
                    └─────────┬─────────┘
                              │
                    ┌─────────┴─────────┐
                    │ SMB/CIFS Server   │
                    │                   │
                    │ ┌───────────────┐ │
                    │ │ Samba/SMB     │ │
                    │ │ Service       │ │
                    │ │ (Port 445)    │ │
                    │ └───────────────┘ │
                    │                   │
                    │ ┌───────────────┐ │
                    │ │ Shared Dirs   │ │
                    │ │ /srv/samba/   │ │
                    │ │ ├─data        │ │
                    │ │ ├─vm          │ │
                    │ │ └─backup      │ │
                    │ └───────────────┘ │
                    └───────────────────┘

SMB/CIFS Server Configuration​

1. Install Samba Server​

# Update package list
sudo apt update

# Install Samba server
sudo apt install samba samba-common-bin

# Install additional utilities
sudo apt install cifs-utils

# Start and enable Samba services
sudo systemctl start smbd
sudo systemctl enable smbd
sudo systemctl start nmbd
sudo systemctl enable nmbd

# Check service status
sudo systemctl status smbd
sudo systemctl status nmbd

2. Create Shared Directories​

# Create directories for SMB shares
sudo mkdir -p /srv/samba/{data,vm,backup,iso,templates}

# Create a dedicated samba group
sudo groupadd smbgroup

# Create samba user
sudo useradd -M -d /srv/samba -s /usr/sbin/nologin -G smbgroup smbuser

# Set ownership and permissions
sudo chown -R smbuser:smbgroup /srv/samba/
sudo chmod -R 755 /srv/samba/

# Set SELinux context (if SELinux is enabled)
sudo setsebool -P samba_enable_home_dirs on
sudo setsebool -P samba_export_all_rw on

3. Configure Samba​

# Backup original Samba configuration
sudo cp /etc/samba/smb.conf /etc/samba/smb.conf.backup.$(date +%Y%m%d)

# Create new Samba configuration
sudo tee /etc/samba/smb.conf > /dev/null << 'EOF'
# Samba Configuration for Proxmox Storage

[global]
    # Server identification
    workgroup = WORKGROUP
    server string = Proxmox Storage Server
    netbios name = PROXMOX-STORAGE
    
    # Protocol versions
    server min protocol = SMB2
    server max protocol = SMB3
    client min protocol = SMB2
    client max protocol = SMB3
    
    # Security settings
    security = user
    map to guest = bad user
    guest account = nobody
    
    # Performance and reliability
    socket options = TCP_NODELAY IPTOS_LOWDELAY SO_RCVBUF=131072 SO_SNDBUF=131072
    read raw = yes
    write raw = yes
    max xmit = 65535
    dead time = 15
    getwd cache = yes
    
    # Logging
    log file = /var/log/samba/log.%m
    max log size = 1000
    log level = 1
    
    # Character set
    unix charset = UTF-8
    dos charset = CP850
    
    # Disable printing
    load printers = no
    printing = bsd
    printcap name = /dev/null
    disable spoolss = yes

# Data share - read/write access
[data]
    comment = Data Storage
    path = /srv/samba/data
    browseable = yes
    writable = yes
    guest ok = no
    valid users = @smbgroup
    create mask = 0664
    directory mask = 0775
    force group = smbgroup

# VM storage - high performance
[vm]
    comment = VM Storage
    path = /srv/samba/vm
    browseable = yes
    writable = yes
    guest ok = no
    valid users = @smbgroup
    create mask = 0664
    directory mask = 0775
    force group = smbgroup
    # Performance optimizations for VM storage
    strict allocate = yes
    allocation roundup size = 1048576

# Backup storage
[backup]
    comment = Backup Storage
    path = /srv/samba/backup
    browseable = yes
    writable = yes
    guest ok = no
    valid users = @smbgroup
    create mask = 0664
    directory mask = 0775
    force group = smbgroup

# ISO storage - read-only
[iso]
    comment = ISO Images
    path = /srv/samba/iso
    browseable = yes
    writable = no
    guest ok = yes
    read only = yes

# Template storage
[templates]
    comment = VM Templates
    path = /srv/samba/templates
    browseable = yes
    writable = yes
    guest ok = no
    valid users = @smbgroup
    create mask = 0664
    directory mask = 0775
    force group = smbgroup
EOF

4. Create Samba Users​

# Add system user to samba group
sudo usermod -a -G smbgroup $USER

# Create Samba user (this will prompt for password)
sudo smbpasswd -a smbuser

# Enable the Samba user
sudo smbpasswd -e smbuser

# Verify Samba users
sudo pdbedit -L -v

5. Configure Firewall​

# For Ubuntu/Debian with ufw
sudo ufw allow samba

# Or manually allow SMB ports
sudo ufw allow 139/tcp
sudo ufw allow 445/tcp
sudo ufw allow 137/udp
sudo ufw allow 138/udp

# For CentOS/RHEL with firewalld
sudo firewall-cmd --permanent --add-service=samba
sudo firewall-cmd --reload

# Check firewall status
sudo ufw status
# or
sudo firewall-cmd --list-all

6. Test Samba Configuration​

# Test Samba configuration syntax
sudo testparm

# Restart Samba services
sudo systemctl restart smbd nmbd

# Check service status
sudo systemctl status smbd nmbd

# Test local access
smbclient -L localhost -U smbuser

# List shares
smbclient -L //localhost -U smbuser

Proxmox CIFS Client Configuration​

1. Install CIFS Client​

# Install CIFS utilities
apt update
apt install cifs-utils

# Verify installation
mount.cifs --version

2. Create Credentials File​

# Create secure credentials file
sudo mkdir -p /etc/cifs-credentials

# Create credentials file for each share/user
sudo tee /etc/cifs-credentials/smbuser > /dev/null << 'EOF'
username=smbuser
password=your_password_here
domain=WORKGROUP
EOF

# Secure the credentials file
sudo chmod 600 /etc/cifs-credentials/smbuser
sudo chown root:root /etc/cifs-credentials/smbuser

3. Create Mount Points​

# Create mount point directories
mkdir -p /mnt/pve/smb-{data,vm,backup,iso,templates}

# Verify directories
ls -la /mnt/pve/ | grep smb

4. Test Manual Mount​

# Test manual mount with SMB3
mount -t cifs //192.168.1.100/data /mnt/pve/smb-data \
  -o credentials=/etc/cifs-credentials/smbuser,vers=3.0,iocharset=utf8

# Test manual mount with SMB2
mount -t cifs //192.168.1.100/data /mnt/pve/smb-data \
  -o credentials=/etc/cifs-credentials/smbuser,vers=2.0,iocharset=utf8

# Verify mount
df -h | grep cifs
ls /mnt/pve/smb-data/

# Test write access
touch /mnt/pve/smb-data/test-file
ls -la /mnt/pve/smb-data/test-file
rm /mnt/pve/smb-data/test-file

# Unmount for configuration
umount /mnt/pve/smb-data

5. Configure Persistent Mounts​

# Backup current fstab
cp /etc/fstab /etc/fstab.backup.$(date +%Y%m%d)

# Add CIFS mounts to fstab
cat >> /etc/fstab << 'EOF'

# CIFS/SMB Mounts for Proxmox Storage
//192.168.1.100/data      /mnt/pve/smb-data      cifs    credentials=/etc/cifs-credentials/smbuser,vers=3.0,iocharset=utf8,file_mode=0664,dir_mode=0775,uid=root,gid=root,_netdev 0 0
//192.168.1.100/vm        /mnt/pve/smb-vm        cifs    credentials=/etc/cifs-credentials/smbuser,vers=3.0,iocharset=utf8,file_mode=0664,dir_mode=0775,uid=root,gid=root,_netdev,cache=strict 0 0
//192.168.1.100/backup    /mnt/pve/smb-backup    cifs    credentials=/etc/cifs-credentials/smbuser,vers=3.0,iocharset=utf8,file_mode=0664,dir_mode=0775,uid=root,gid=root,_netdev 0 0
//192.168.1.100/iso       /mnt/pve/smb-iso       cifs    credentials=/etc/cifs-credentials/smbuser,vers=3.0,iocharset=utf8,ro,_netdev 0 0
//192.168.1.100/templates /mnt/pve/smb-templates cifs    credentials=/etc/cifs-credentials/smbuser,vers=3.0,iocharset=utf8,file_mode=0664,dir_mode=0775,uid=root,gid=root,_netdev 0 0
EOF

6. CIFS Mount Options Explained​

# Essential CIFS mount options:

# Authentication
credentials=/path/file   # Credentials file location
username=user           # Username for authentication
password=pass           # Password (insecure, use credentials file)
domain=DOMAIN          # Windows domain

# Protocol Version
vers=3.0               # SMB 3.0 (recommended)
vers=2.1               # SMB 2.1
vers=2.0               # SMB 2.0
vers=1.0               # SMB 1.0 (deprecated)

# Character Encoding
iocharset=utf8         # Character set for filenames
unicode                # Enable Unicode support

# File Permissions
file_mode=0664         # Default file permissions
dir_mode=0775          # Default directory permissions
uid=1000               # User ID for files
gid=1000               # Group ID for files
forceuid               # Force all files to specified uid
forcegid               # Force all files to specified gid

# Performance Options
cache=strict           # Strict caching (better for VMs)
cache=loose            # Loose caching (better performance)
cache=none             # No caching
rsize=65536           # Read buffer size
wsize=65536           # Write buffer size

# Network Options
_netdev               # Network device (wait for network)
soft                  # Soft mount (return errors on timeout)
hard                  # Hard mount (retry indefinitely)

7. Mount CIFS Shares​

# Mount all CIFS shares
mount -a

# Verify all mounts
df -h | grep cifs
mount | grep cifs

# Test each mount point
ls /mnt/pve/smb-data/
ls /mnt/pve/smb-vm/
ls /mnt/pve/smb-backup/

Proxmox Storage Configuration​

1. Add CIFS Storage via Web Interface​

  1. Access Proxmox Web Interface

    • Navigate to your Proxmox web interface
    • Go to Datacenter → Storage

  2. Add CIFS Storage

    • Click Add → CIFS
    • Configure the following:
      • ID: smb-data (unique identifier)
      • Server: 192.168.1.100
      • Share: data
      • Username: smbuser
      • Password: your_password
      • Content: Select appropriate content types
      • Nodes: Select which nodes can access this storage

  3. Advanced Options

    • SMB Version: Select 3.0 (recommended)
    • Options: Add custom mount options if needed

2. Add CIFS Storage via Command Line​

# Backup current storage configuration
cp /etc/pve/storage.cfg /etc/pve/storage.cfg.backup.$(date +%Y%m%d)

# Add CIFS storage definitions
cat >> /etc/pve/storage.cfg << 'EOF'

# CIFS/SMB Storage Definitions
cifs: smb-data
        server 192.168.1.100
        share data
        path /mnt/pve/smb-data
        username smbuser
        password your_password_here
        content images,vztmpl
        smbversion 3
        options file_mode=0664,dir_mode=0775

cifs: smb-vm
        server 192.168.1.100
        share vm
        path /mnt/pve/smb-vm
        username smbuser
        password your_password_here
        content images
        smbversion 3
        options file_mode=0664,dir_mode=0775,cache=strict

cifs: smb-backup
        server 192.168.1.100
        share backup
        path /mnt/pve/smb-backup
        username smbuser
        password your_password_here
        content backup
        smbversion 3

cifs: smb-iso
        server 192.168.1.100
        share iso
        path /mnt/pve/smb-iso
        username smbuser
        password your_password_here
        content iso
        smbversion 3

cifs: smb-templates
        server 192.168.1.100
        share templates
        path /mnt/pve/smb-templates
        username smbuser
        password your_password_here
        content vztmpl
        smbversion 3
EOF

3. Verify Storage Configuration​

# Check storage status
pvesm status

# List all storage
pvesm list

# Test storage access
pvesm path smb-data:100/vm-100-disk-0.qcow2

# Check storage capacity
pvesm status smb-data

Performance Optimization​

1. SMB Server Tuning​

# Optimize Samba server performance
# Edit /etc/samba/smb.conf and add/modify:

[global]
    # Performance optimizations
    socket options = TCP_NODELAY IPTOS_LOWDELAY SO_RCVBUF=131072 SO_SNDBUF=131072
    read raw = yes
    write raw = yes
    max xmit = 65535
    
    # Async I/O
    aio read size = 16384
    aio write size = 16384
    aio write behind = true
    
    # Oplocks for better caching
    oplocks = yes
    level2 oplocks = yes
    kernel oplocks = no
    
    # Memory mapping
    use mmap = yes
    
    # Disable unnecessary features
    load printers = no
    disable spoolss = yes

# Restart Samba after changes
sudo systemctl restart smbd

2. Client-Side Optimization​

# Optimize CIFS client mount options
# Add to /etc/fstab mount options:
# cache=strict,rsize=65536,wsize=65536,actimeo=1

# Example optimized fstab entry:
# //192.168.1.100/vm /mnt/pve/smb-vm cifs credentials=/etc/cifs-credentials/smbuser,vers=3.0,cache=strict,rsize=65536,wsize=65536,actimeo=1,_netdev 0 0

3. Network Optimization​

# Enable jumbo frames (if supported)
# On SMB server
sudo ip link set dev eth0 mtu 9000

# On Proxmox clients
ip link set dev eth0 mtu 9000

# Add to /etc/network/interfaces for persistence:
# auto eth0
# iface eth0 inet static
#     address 192.168.1.10/24
#     gateway 192.168.1.1
#     mtu 9000

4. Kernel Tuning​

# Optimize kernel parameters for CIFS
cat >> /etc/sysctl.conf << 'EOF'

# CIFS Performance Tuning
net.core.rmem_default = 262144
net.core.rmem_max = 16777216
net.core.wmem_default = 262144
net.core.wmem_max = 16777216
net.ipv4.tcp_rmem = 4096 65536 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216
EOF

# Apply settings
sysctl -p

Security Configuration​

1. SMB Encryption​

# Enable SMB encryption in /etc/samba/smb.conf
[global]
    # Force SMB encryption
    smb encrypt = required
    
    # Or allow but don't require
    # smb encrypt = desired

# For specific shares
[data]
    smb encrypt = required

2. Access Control​

# Restrict access by IP in /etc/samba/smb.conf
[global]
    hosts allow = 192.168.1.0/24 127.0.0.1
    hosts deny = ALL

# Per-share access control
[data]
    hosts allow = 192.168.1.10 192.168.1.11 192.168.1.12

3. User and Group Management​

# Create dedicated groups for different access levels
sudo groupadd smb-readonly
sudo groupadd smb-readwrite
sudo groupadd smb-admin

# Add users to appropriate groups
sudo usermod -a -G smb-readwrite smbuser

# Configure share permissions
[data]
    valid users = @smb-readwrite, @smb-admin
    read list = @smb-readonly
    write list = @smb-readwrite, @smb-admin
    admin users = @smb-admin

Troubleshooting​

Common Issues and Solutions​

Mount Failures

# Test SMB server connectivity
smbclient -L //192.168.1.100 -U smbuser

# Test network connectivity
ping 192.168.1.100
telnet 192.168.1.100 445

# Check SMB services
sudo systemctl status smbd nmbd

# Debug mount issues
mount -t cifs //192.168.1.100/data /mnt/pve/smb-data -v \
  -o credentials=/etc/cifs-credentials/smbuser,vers=3.0

# Check system logs
journalctl -u smbd
tail -f /var/log/samba/log.smbd

Diagnostic Commands​

# CIFS client diagnostics
mount | grep cifs
df -h | grep cifs
cat /proc/fs/cifs/Stats

# SMB server diagnostics
sudo testparm
smbstatus
sudo smbstatus -S

# Network diagnostics
ss -tuln | grep 445
netstat -an | grep 445
nmap -p 445 192.168.1.100

# System logs
journalctl -f | grep -i smb
tail -f /var/log/samba/log.smbd

Monitoring and Maintenance​

1. SMB Health Monitoring​

# Create SMB monitoring script
cat > /usr/local/bin/smb-monitor.sh << 'EOF'
#!/bin/bash

LOG_FILE="/var/log/smb-monitor.log"

# Function to check SMB mount health
check_smb_mount() {
    local mount_point="$1"
    local name="$2"
    
    if mountpoint -q "$mount_point"; then
        if timeout 10 ls "$mount_point" >/dev/null 2>&1; then
            echo "$(date): ✓ $name is healthy"
            return 0
        else
            echo "$(date): ✗ $name is unresponsive"
            return 1
        fi
    else
        echo "$(date): ✗ $name is not mounted"
        return 1
    fi
}

# Check all SMB mounts
for mount in data vm backup iso templates; do
    check_smb_mount "/mnt/pve/smb-$mount" "smb-$mount"
done >> "$LOG_FILE"

# Log SMB server status (if local)
if systemctl is-active --quiet smbd; then
    echo "$(date): SMB Server Status:" >> "$LOG_FILE"
    smbstatus -b >> "$LOG_FILE" 2>&1
fi
EOF

chmod +x /usr/local/bin/smb-monitor.sh

# Add to crontab
echo "*/5 * * * * /usr/local/bin/smb-monitor.sh" | crontab -

2. Automated Remount Script​

# Create automatic remount script
cat > /usr/local/bin/smb-remount.sh << 'EOF'
#!/bin/bash

LOG_FILE="/var/log/smb-remount.log"

remount_smb() {
    local mount_point="$1"
    local name="$2"
    
    echo "$(date): Attempting to remount $name" >> "$LOG_FILE"
    
    # Try to unmount first
    umount "$mount_point" 2>/dev/null
    
    # Wait a moment
    sleep 2
    
    # Remount
    if mount "$mount_point"; then
        echo "$(date): ✓ Successfully remounted $name" >> "$LOG_FILE"
        return 0
    else
        echo "$(date): ✗ Failed to remount $name" >> "$LOG_FILE"
        return 1
    fi
}

# Check and remount failed SMB mounts
for mount in data vm backup iso templates; do
    mount_point="/mnt/pve/smb-$mount"
    if ! mountpoint -q "$mount_point" || ! timeout 5 ls "$mount_point" >/dev/null 2>&1; then
        remount_smb "$mount_point" "smb-$mount"
    fi
done
EOF

chmod +x /usr/local/bin/smb-remount.sh

3. Log Rotation​

# Configure log rotation for SMB logs
cat > /etc/logrotate.d/smb-custom << 'EOF'
/var/log/smb-monitor.log
/var/log/smb-remount.log {
    daily
    rotate 7
    compress
    delaycompress
    missingok
    notifempty
    create 644 root root
}
EOF

Best Practices​

1. Security Best Practices​

  • Use SMB 3.0+: Always use modern SMB versions with encryption
  • Strong Authentication: Implement strong passwords and consider domain authentication
  • Network Segmentation: Isolate SMB traffic using VLANs
  • Access Control: Use IP restrictions and user-based access controls
  • Regular Updates: Keep Samba and client software updated

2. Performance Best Practices​

  • Dedicated Networks: Use dedicated gigabit or 10GbE networks for storage
  • Optimize Mount Options: Use appropriate caching and buffer sizes
  • Server Tuning: Optimize Samba server configuration for your workload
  • Monitor Performance: Regular monitoring of throughput and latency
  • Load Distribution: Distribute load across multiple SMB servers

3. Reliability Best Practices​

  • Redundancy: Implement server and network redundancy
  • Monitoring: Comprehensive monitoring and alerting
  • Backup Strategies: Regular backups of SMB server configuration and data
  • Documentation: Maintain detailed documentation of configurations
  • Testing: Regular testing of failover and recovery procedures

CIFS/SMB provides excellent compatibility and feature richness for Proxmox storage, especially in mixed Windows/Linux environments. When properly configured with modern SMB versions, it offers good performance and robust security features suitable for enterprise virtualization deployments.

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