Interact with a server using the SMB 2/3 Protocol
SMBv2 and v3 Client for Python.
SMB is a network file sharing protocol and has numerous iterations over the years. This library implements the SMBv2 and SMBv3 protocol based on the MS-SMB2 document.
- Negotiation of the SMB 2.0.2 protocol to SMB 3.1.1 (Windows 10/Server 2016)
- Authentication with both NTLM and Kerberos
- Message signing
- Message encryption (SMB 3.x.x+)
- Connect to a Tree/Share
- Opening of files, pipes and directories
- Set create contexts when opening files
- Read and writing of files and pipes
- Sending IOCTL commands
- Sending of multiple messages in one packet (compounding)
- Experimental support for both standalone and DFS server shares
This is definitely not feature complete as SMB is quite a complex protocol, see backlog for features that would be nice to have in this library.
To use Kerberos authentication on Linux, further dependencies are required, to install these dependencies run
# for Debian/Ubuntu/etc: sudo apt-get install gcc python-dev libkrb5-dev pip install smbprotocol[kerberos] # for RHEL/CentOS/etc: sudo yum install gcc python-devel krb5-devel krb5-workstation python-devel pip install smbprotocol[kerberos]
Kerberos auth with Windows should just work out of the box with the
pyspnego library but on Linux, the
python-gssapi library must be installed and
smbprotocol requires a particular GSSAPI extension to be available to
work. This extension should be installed on the majority of MIT or Heimdal Kerberos installs but that is not a
guarantee. To verify that Kerberos is available on Linux you can run the following check in a Python console:
try: from gssapi.raw import inquire_sec_context_by_oid print("python-gssapi extension is available") except ImportError as exc: print("python-gssapi extension is not available: %s" % str(exc))
If it isn't available, then either a newer version of the system's gssapi implementation needs to be setup and python-gssapi compiled against that newer version. In the absence of this extension, only NTLM auth is used.
To install smbprotocol, simply run
pip install smbprotocol # To install with Kerberos support pip install smbprotocol[kerberos]
This will download the required packages that are used in this package and get your Python environment ready to go.
One of the first steps as part of the SMB protocol is to negotiate the dialect used and other features that are available. Currently smbprotocol supports the following dialects;
2.0.0: Added with Server 2008/Windows Vista
2.1.0: Added with Server 2008 R2/Windows 7
3.0.0: Added with Server 2012/Windows 8
3.0.2: Added with Server 2012 R2/Windows 8.1
3.1.1: Added with Server 2016/Windows10
Each dialect adds in more features to the protocol where some are minor but some are major. One major changes is in Dialect 3.x where it added message encryption. Message encryption is set to True by default and needs to be overridden when creating a Session object for the older dialects.
By default, the negotiation process will use the latest dialect that is supported by the server but this can be overridden if required. When this is done by the following code
import uuid from smbprotocol.connection import Connection, Dialects connection = Connection(uuid.uuid4(), "server", 445) connection.connect(Dialects.SMB_3_0_2)
While you shouldn't want to downgrade to an earlier version, this does allow you to set a minimum dialect version if required.
There are 2 different APIs you can use with this library.
smbprotocol: Low level interface that can do whatever you want but quite verbose
smbclient: Higher level interface that implements the builtin
os.pathfile system functions but for SMB support
examples folder contains some examples of both the high and low level
interface but for everyday user's it is recommended to use
smbclient as it
is a lot simpler.
The higher level interface
smbclient is designed to make this library easier
for people to use for simple and common use cases. It is designed to replicate
os.path filesystem functions like
os.path.exists(). It is also designed to handle connections
to a DFS target unlike
A connection made by
smbclient is kept in a pool and re-used for future
requests to the same server until the Python process exists. This makes
authentication simple and only required for the first call to the server. Any
DFS referrals are also cached in that Python process. This optimises any
future requests to that same DFS namespace.
The functions in
smbclient have a global config object that can be used to
set any connection defaults to use for any future connections. It can also be
used to specify any domain based DFS settings for more advanced setups. It is
recommended to use
ClientConfig() to set any global credentials like so:
import smbclient smbclient.ClientConfig(username='user', password='password')
ClientConfig is a singleton and any future instanciations of that
object will just update the keys being set. You can set the following keys on
client_guid: The client GUID to identify the client to the server on a new connection
username: The default username to use when creating a new SMB session if explicit credentials weren't set
password: The default password to use for authentication
domain_controller: The domain controller hostname. This is useful for environments with DFS servers as it is used to identify the DFS domain information automatically
skip_dfs: Whether to skip doing any DFS resolution, useful if there is a bug or you don't want to waste any roundtrip requesting referrals
auth_protocol: The authentication protocol to use;
require_secure_negotiate: Control whether the client validates the negotiation info when connecting to a share (default:
- More information can be found on SMB3 Secure Dialect Negotiation
As well as setting the default credentials on the
ClientConfig you can also
specify the credentials and other connection parameters on each
function or when registering a new server. These functions accept the
username: The username used to connect to the share
password: The password used to connect to the share
port: Override the default port (
445) to connect to
encrypt: Whether to force encryption on the connection, requires SMBv3 or newer on the remote server (default:
connection_timeout: Override the connection timeout in seconds (default:
If using Kerberos authentication and a Kerberos ticket has already set by
smbclient will automatically use those credentials without
having to be explicitly set. If no ticket has been retrieved or you wish to use
different credentials then set the default credentials on the
password on the first request to the server.
For example I only need to set the credentials on the first request to create the directory and not for the subsequent file creation in that dir.
import smbclient # Optional - specify the default credentials to use on the global config object smbclient.ClientConfig(username='user', password='pass') # Optional - register the credentials with a server (overrides ClientConfig for that server) smbclient.register_session("server", username="user", password="pass") smbclient.mkdir(r"\\server\share\directory", username="user", password="pass") with smbclient.open_file(r"\\server\share\directory\file.txt", mode="w") as fd: fd.write(u"file contents")
If you wish to reset the cache you can either start a new Python process or
smbclient.reset_connection_cache() to close all the connections that
have been cached by the client.
This library makes use of the builtin Python logging facilities. Log messages
are logged to the
smbprotocol named logger as well as
* is each python script in the
These logs are really useful when debugging issues as they give you a more step by step snapshot of what it is doing and what may be going wrong. The debug side will also print out a human readable string of each SMB packet that is sent out from the client so it can get very verbose.
To this module, you need to install some pre-requisites first. This can be done by running;
pip install -r requirements-test.txt # you can also run tox by installing tox pip install tox
From there to run the basic tests run;
py.test -v --pep8 --cov smbprotocol --cov-report term-missing # or with tox 2.7, 2.7, 3.4, 3.5, and 3.6 tox
There are extra tests that only run when certain environment variables are set. To run these tests set the following variables;
SMB_USER: The username to authenticate with
SMB_PASSWORD: The password to authenticate with
SMB_SERVER: The IP or hostname of the server to authenticate with
SMB_PORT: The port the SMB server is listening on, default is
SMB_SHARE: The name of the share to connect to, a share with this name must exist as well as a share with the name
$SMB_SHARE-encryptedmust also exist that forces encryption
From here running
py.test with these environment variables set will
activate the integration tests.
This requires either Windows 10 or Server 2016 as they support Dialect 3.1.1 which is required by the tests.
If you don't have access to a Windows host, you can use Docker to setup a Samba container and use that as part of the tests. To do so run the following bash commands;
source ./build_helpers/lib.sh lib::setup::smb_server
This command will also set the required
SMB_* env vars used in testing.
Here is a list of features that I would like to incorporate, PRs are welcome if you want to implement them yourself;
- Multiple channel support to speed up large data transfers
- Lots and lots more...
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