SMB/CIFS Windows Shares

Install CIFS utilities

# Ubuntu/Debian
sudo apt install cifs-utils samba samba-common-bin

# RHEL/CentOS
sudo yum install cifs-utils samba-client

Mount SMB share

Basic mount

sudo mount -t cifs //server/share /mnt/share -o username=user,password=pass

Better: Use credentials file

Create ~/.smbcredentials:

username=myuser
password=mypassword
domain=WORKGROUP

Set permissions:

chmod 600 ~/.smbcredentials

Mount:

sudo mount -t cifs //server/share /mnt/share -o credentials=~/.smbcredentials

Permanent mount (fstab)

Add to /etc/fstab:

//server/share  /mnt/share  cifs  credentials=/home/user/.smbcredentials,uid=1000,gid=1000  0  0

Common mount options

username=user           # Username
password=pass           # Password (not recommended)
credentials=/path/file  # Credentials file
uid=1000               # File owner UID
gid=1000               # File owner GID  
file_mode=0755         # File permissions
dir_mode=0755          # Directory permissions
vers=3.0               # SMB version
sec=ntlmssp            # Security mode
_netdev                # Wait for network

List shares

# List shares on server
smbclient -L //server -U username

# Anonymous
smbclient -L //server -N

Interactive access

# Connect to share
smbclient //server/share -U username

# Inside smbclient:
ls                  # List files
get file.txt        # Download
put localfile.txt   # Upload
mget *.txt          # Download multiple
mput *.txt          # Upload multiple
cd directory        # Change directory
pwd                 # Print working directory
help                # Show commands
exit                # Quit

Copy files

# Using smbclient
smbclient //server/share -U username -c "get file.txt"

# Recursive get
smbclient //server/share -U username -c "prompt OFF; recurse ON; mget *"

Test with smbget

# Download file
smbget smb://server/share/file.txt -U username

# Recursive download
smbget -R smb://server/share/ -U username

Mount Windows share

# Windows 10/11 share
sudo mount -t cifs //192.168.1.100/Users /mnt/windows \
  -o username=WindowsUser,password=pass,vers=3.0

Domain authentication

sudo mount -t cifs //server/share /mnt/share \
  -o username=user,password=pass,domain=DOMAIN

Security modes

# NTLMv2 (most common)
-o sec=ntlmssp

# Kerberos
-o sec=krb5

# NTLM
-o sec=ntlm

# No security  
-o sec=none

SMB versions

# SMB 3.0 (Windows 8/Server 2012+)
-o vers=3.0

# SMB 2.1 (Windows 7/Server 2008R2)
-o vers=2.1

# SMB 1.0 (deprecated, insecure)
-o vers=1.0

Troubleshooting

Permission denied

# Check credentials
smbclient -L //server -U username

# Try different SMB version
sudo mount -t cifs //server/share /mnt -o username=user,vers=2.1

Host is down

# Test connectivity
ping server
telnet server 445

# Check firewall
sudo nmap -p 445 server

List more details

# Verbose mount
sudo mount -t cifs //server/share /mnt -o username=user,vers=3.0 -v

Unmount

sudo umount /mnt/share

# Force unmount
sudo umount -f /mnt/share
sudo umount -l /mnt/share  # Lazy

Check mounted CIFS shares

mount | grep cifs
df -h | grep cifs

Samba server (share Linux folder)

Install

sudo apt install samba

Configure /etc/samba/smb.conf

[MyShare]
   path = /path/to/share
   browseable = yes
   read only = no
   guest ok = no
   create mask = 0755

Add Samba user

sudo smbpasswd -a username

Restart Samba

sudo systemctl restart smbd
sudo systemctl restart nmbd

Test configuration

testparm

Firewall (for Samba server)

# Ubuntu UFW
sudo ufw allow samba

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

Common issues

"Host is down"

• Check network connectivity
• Verify server is running
• Check firewall (port 445)

"Permission denied"

• Verify credentials
• Check share permissions
• Try different security mode

"Invalid argument"

• Try different SMB version
• Check mount options syntax

Performance tuning

# Larger buffer
-o rsize=130048,wsize=130048

# No caching (for consistency)
-o cache=none

# More aggressive caching
-o cache=strict

AutoFS for SMB

/etc/auto.master:

/mnt/cifs  /etc/auto.cifs  --timeout=60

/etc/auto.cifs:

share  -fstype=cifs,credentials=/root/.smbcredentials  ://server/share

Complete example

# 1. Create mount point
sudo mkdir -p /mnt/windowsshare

# 2. Create credentials file
cat > ~/.smbcredentials << EOF
username=myuser
password=mypassword
domain=WORKGROUP
EOF
chmod 600 ~/.smbcredentials

# 3. Test mount
sudo mount -t cifs //192.168.1.100/Share /mnt/windowsshare \
  -o credentials=$HOME/.smbcredentials,uid=1000,gid=1000,vers=3.0

# 4. Add to fstab
echo "//192.168.1.100/Share  /mnt/windowsshare  cifs  credentials=$HOME/.smbcredentials,uid=1000,gid=1000,vers=3.0,_netdev  0  0" | sudo tee -a /etc/fstab

# 5. Test fstab
sudo mount -a