Many administrators face this frustrating scenario: You've configured a Samba public share with guest ok = yes, yet Windows clients stubbornly demand authentication. This contradicts the intended behavior where public shares should allow anonymous access.

The root cause typically lies in three key areas:

[global]
   security = user
   map to guest = Bad User
   guest account = nobody

[DSMPubblica]
   path = /var/dsm/pubblica
   guest ok = yes
   guest only = yes
   read only = no
   force user = nobody
   force group = nogroup
   create mask = 0777
   directory mask = 0777

Windows clients have particular requirements:

• Enable insecure guest access in Windows 10/11: gpedit.msc → Computer Configuration → Administrative Templates → Network → Lanman Workstation → "Enable insecure guest logons"
• For Windows 7/8.1: Registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters\AllowInsecureGuestAuth set to 1

When troubleshooting, examine these log entries:

tail -f /var/log/samba/log.smbd
smbclient -L //localhost -U%
testparm -s

The complete permission chain must align:

chmod -R 777 /var/dsm/pubblica
chown -R nobody:nogroup /var/dsm/pubblica
setsebool -P samba_export_all_rw on  # For SELinux systems

This tested setup resolves the password prompt issue:

[global]
   workgroup = WORKGROUP
   server string = Samba Server
   security = user
   map to guest = Bad User
   guest account = nobody
   dns proxy = no
   log file = /var/log/samba/log.%m
   max log size = 1000
   socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192

[Public]
   path = /samba/public
   browsable = yes
   writable = yes
   guest ok = yes
   read only = no
   create mask = 0777
   directory mask = 0777
   force user = nobody
   force group = nogroup

For Windows clients accessing Linux shares, ensure NTFS permissions don't conflict:

net use Z: \\server\public /user:guest *
icacls Z:\ /grant Everyone:(OI)(CI)F

When configuring mixed-access Samba shares (both public and private), Windows clients often stubbornly demand credentials even for designated guest-accessible shares. This occurs despite seemingly correct configurations, manifesting in two key symptoms:

• Windows requesting credentials for shares marked guest ok = yes
• Authentication prompts reappearing after system reboots despite credential caching

Your current setup reveals several common pitfalls in Samba-Windows integration. Let's analyze the core issues:

[global]
  # Problem area 1: Missing security specification
  security = user  # This should be explicitly set
  
  # Problem area 2: Guest account handling
  map to guest = bad user  # Crucial for public shares

[DSMPubblica]
  # Problem area 3: Inconsistent permissions
  force create mode = 777  # Overkill and potentially unsafe

Windows 7/8.1 clients enforce specific authentication protocols that often conflict with Samba's defaults. The smb_pwd_check_ntlmv1 error indicates protocol mismatch.

Essential adjustments for Windows compatibility:

[global]
  # Security protocol adjustments
  client min protocol = NT1
  client max protocol = SMB3
  server min protocol = NT1
  server max protocol = SMB3
  
  # Guest access foundation
  guest account = nobody
  map to guest = bad user

For your public share (DSMPubblica), implement these changes:

[DSMPubblica]
  path = /var/dsm/pubblica
  browseable = yes
  read only = no
  guest ok = yes
  guest only = yes
  force user = nobody
  create mask = 0666
  directory mask = 0777
  
  # Windows-specific optimizations
  store dos attributes = yes
  inherit permissions = yes

For your secured share (DSMUfficio), enhance the existing configuration:

[DSMUfficio]
  path = /var/dsm/ufficio
  valid users = @dsm @administrators
  write list = @dsm
  read list = @administrators
  force group = dsm
  create mask = 0770
  directory mask = 0770
  
  # Security hardening
  ntlm auth = yes
  restrict anonymous = 2

Critical post-configuration steps on Linux:

# Set proper ownership
sudo chown -R nobody:nogroup /var/dsm/pubblica
sudo chmod -R u=rwx,g=rwx,o=rwx /var/dsm/pubblica

# For private share
sudo chown -R root:dsm /var/dsm/ufficio
sudo chmod -R 770 /var/dsm/ufficio

# SELinux contexts (if applicable)
sudo chcon -Rt samba_share_t /var/dsm/pubblica
sudo chcon -Rt samba_share_t /var/dsm/ufficio

Add these registry modifications to prevent credential caching issues:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters]
"RequireSecuritySignature"=dword:00000000
"EnablePlainTextPassword"=dword:00000001
"EnableSecuritySignature"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa]
"LmCompatibilityLevel"=dword:00000001

Essential commands for troubleshooting:

# Test configuration
testparm -v

# Real-time log monitoring
sudo tail -f /var/log/samba/log.smbd

# Client connection testing
smbclient -L //localhost -U%

# Detailed share access check
smbclient //server/DSMPubblica -N -d 3

Before declaring victory, verify:

• Global security = user is set
• map to guest = bad user exists in [global]
• Public share has guest ok = yes AND guest only = yes
• Filesystem permissions match Samba masks
• Windows network discovery is enabled
• Firewall allows SMB ports (445/tcp, 137-139/udp)