Incremental synchronization from SMB with smbprotocol on Linux: NTLM authentication and log control

The Problem
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Recently I needed to sync an SMB share from a NAS with my Linux server. The obvious solution would be smbclient or mount -t cifs, but I wanted:

Incremental synchronization (only new or modified files)
Detect files deleted from the share
Control NTLM authentication directly from code
Silence the obscene amount of logs that smbprotocol spits out

The Python smbprotocol library solved all of this, but there’s no documentation on how to do it properly. Here’s my solution.

Initial Setup
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Install the dependencies:

pip install smbprotocol sqlalchemy pydantic python-dotenv

The basic idea: maintain a SQLite database with a record of all synchronized files (name, MD5 hash, timestamp). Each execution compares the current share with the database and processes only changes.

Silencing smbprotocol logs
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This is critical. Without controlling it, the library fills your console with debug messages:

import logging

# Silenciar smbprotocol
logging.getLogger('smbprotocol').setLevel(logging.WARNING)
logging.getLogger('smbprotocol.connection').setLevel(logging.WARNING)
logging.getLogger('smbprotocol.session').setLevel(logging.WARNING)

# Tu logger
logger = logging.getLogger('sync_smb')
logger.setLevel(logging.INFO)
handler = logging.StreamHandler()
handler.setFormatter(logging.Formatter('%(asctime)s - %(levelname)s - %(message)s'))
logger.addHandler(handler)

This reduces logs to something reasonable. Without this, each operation generates 50 lines of garbage.

SQLite Database Structure
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from datetime import datetime
from sqlalchemy import create_engine, Column, String, DateTime, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

Base = declarative_base()

class SyncedFile(Base):
    __tablename__ = 'synced_files'
    
    filename = Column(String, primary_key=True)
    md5_hash = Column(String)
    file_size = Column(Integer)
    last_modified = Column(DateTime)
    sync_timestamp = Column(DateTime, default=datetime.utcnow)

engine = create_engine('sqlite:///smb_sync.db')
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)

NTLM Connection
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from smbprotocol.session import Session
from smbprotocol.tree import TreeConnect
import socket

username = "DOMINIO\\usuario"  # Formato NETBIOS\usuario
password = "contraseña"
host = "192.168.x.x"
share = "compartido"

# Conexión básica
connection = smbprotocol.connection.Connection(
    uuid.uuid4(),
    host,
    445,
)
connection.connect()

session = Session(connection, username, password)
session.connect()

tree = TreeConnect(session, f"\\\\{host}\\{share}")
tree.connect()

NTLM is negotiated automatically. You don’t need to do anything special, but make sure you use the correct DOMINIO\usuario format.