An Introduction to the SMB Protocol - Using Samba, Second Edition [Book]
An Introduction to the SMB Protocol Now we're going to cover some low-level technical details Selection from Using Samba, Second Edition [Book] The client and server must complete three steps to establish a connection to a resource. SMB is an important protocol because of the large number of PCs out a connection, clients can then send commands (SMBs) to the server. subnet NetBIOS API. • Combined with a transport protocol to be called NetBEUI – NetBIOS Association CIFS specification History table. • Samba.
The computer named maya shares a printer to the network, and the computer named toltec shares a disk directory. Two computers that both have resources to share This brings out an important point in Samba terminology: A server is a computer with a resource to share.
A client is a computer that wishes to use that resource. A computer can be a client, a server, or both, or it can be neither at any given time. Microsoft Windows products have both the SMB client and server built into the operating system, and it is common to find Windows acting as a server, client, both, or neither at any given time in a production network.Linux Samba
Although Samba has been developed primarily to function as a server, there are also ways that it and associated software can act as an SMB client. As with Windows, it is even possible to set up a Unix system to act as an SMB client and not as a server.
See Chapter 5 for more details on this topic. Negotiate the protocol variant. Set session parameters, and make a tree connection to a resource. This DC then contacts a DC in the first trusted domain to check whether the user is valid before instructing the server to grant access to the resource.
Samba can even particpate in trust relationships with other domains. This rule may change in a future release. Make sure to check the Samba web site for the latest release and updates. A domain member server does not authenticate users logging on to the domain, but still handles security functions such as file permissions for domain users accessing its resources. Thus, it is possible to have a Samba server support domain logons for a network of Windows clients, including the most recent releases from Microsoft.
This setup can result in a very stable, high-performance, and more secure network; it also provides the benefit of not having to purchase per-seat Windows Client Acccess Licenses CALs from Microsoft. The current release also supports migration of user and group information from a Windows NT 4. Local Nested Groups Windows has always supported the concept of adding groups as members of other groups. Current Samba releases also support this capability, by using Winbind to define a group that is local to the server and can contain Windows domain groups.
Upon receiving a request for the list of users in the local group, Winbind expands the membership of any nested domain groups that it contains. This feature can be useful, such as when you want to set the group ownership of a file that must be accessible by multiple domain groups. You define on the Samba host a local group that contains all of the appropriate domain groups.
Of course, it is possible to perform an equivalent function if the filesystem supports access control lists.
Server Message Block
However, local groups have the advantage of requiring you to deal with only one group instead of many. Unicode and Internationalization Unicode is the pervasive means of representing non-English character sets on Windows NT-based computers. The UCS2 encoding represents each character using 16 bits, providing more than enough combinations to handle more languages that any of us have to manage on our network. Building Samba to include Unicode support is covered in Chapter 2.
User and Group Account Storage Plug-in Modules Libraries knows as passdb modules allow an administrator to choose the persistent storage backend for user and group information. Prior versions of Samba supported this feature in a limited fashion and required the storage interface—for example, a flat text file smbpasswd or an LDAP directory service—to be defined at compile time.
This approach allows for easy migration from one storage format to another and to have one Samba package that supports the needs of multiple installations. Users and groups and how they are stored are discussed in Chapter 5. Good examples of current VFS modules are the network recycle bin, virus scanners, and filesystem snapshot tools.
User Privileges Recent releases of Samba introduced the ability to grant certain rights, such as the ability to join Windows clients to a Samba domain, to a nonroot user.
Prior versions of Samba required the use of a user account with a uid of 0 that is, the superuser. Being able to delegate such security-sensitive operations goes a long way when managing Samba domains with multiple administrators. Privileges are discussed in the context of users and groups in Chapter 5.
Server Message Block - Wikipedia
Windows Automatic Driver Downloads Samba 2. Future Research in Samba 4. Examples of these projects of these items include: There has been a great deal of confusion about the relationship between Samba 3. Both source code repositories are part of the Samba project. Samba software This section needs to be updated.
Please update this article to reflect recent events or newly available information. As of version 3Samba provides file and print services for Microsoft Windows clients and can integrate with a Windows NT 4.
Samba4 installations can act as an Active Directory domain controller or member server, at Windows domain and forest functional levels. It supports only SMB 2. The platform could be used for traditional NAS, Cloud Gateway, and Cloud Caching devices for providing secure access to files across a network.
Likewise was purchased by EMC Isilon in It has the following advantages over user-space implementations: It provides better performance, and it's easier to implement some features like SMB Direct. It supports SMB 3. Performance issues[ edit ] The use of the SMB protocol has often correlated with a significant increase in broadcast traffic on a network.
NetBIOS functions by broadcasting services available on a particular host at regular intervals. While this usually makes for an acceptable default in a network with a smaller number of hosts, increased broadcast traffic can cause problems as the number of hosts on the network increases. Since the release of Windowsthe use of WINS for name resolution has been deprecated by Microsoft, with hierarchical Dynamic DNS now configured as the default name resolution protocol for all Windows operating systems.
WINS can still be configured on clients as a secondary name resolution protocol for interoperability with legacy Windows environments and applications. Network designers have found that latency has a significant impact on the performance of the SMB 1.
Monitoring reveals a high degree of "chattiness" and a disregard of network latency between hosts. Microsoft has explained that performance issues come about primarily because SMB 1.
Opportunistic locking support has changed with each server release. Opportunistic locking[ edit ] In the SMB protocol, opportunistic locking is a mechanism designed to improve performance by controlling caching of network files by the client.