This is the client VFS module for the SMB3 family of NAS protocols,
(including support for the most recent, most secure dialect SMB3.1.1)
as well as for earlier dialects such as SMB2.1, SMB2 and the older
Common Internet File System (CIFS) protocol. CIFS was the successor
to the original dialect, the Server Message Block (SMB) protocol, the
native file sharing mechanism for most early PC operating systems.

The SMB3 protocol is supported by most modern operating systems
and NAS appliances (e.g. Samba, Windows 10, Windows Server 2016,
MacOS) and even in the cloud (e.g. Microsoft Azure).
The older CIFS protocol was included in Windows NT4, 2000 and XP (and
later) as well by Samba (which provides excellent CIFS and SMB3
server support for Linux and many other operating systems). Use of
dialects older than SMB2.1 is often discouraged on public networks.
This module also provides limited support for OS/2 and Windows ME
and similar very old servers.

This module provides an advanced network file system client
for mounting to SMB3 (and CIFS) compliant servers. It includes
support for DFS (hierarchical name space), secure per-user
session establishment via Kerberos or NTLM or NTLMv2, RDMA
(smbdirect), advanced security features, per-share encryption,
directory leases, safe distributed caching (oplock), optional packet
signing, Unicode and other internationalization improvements.

In general, the default dialects, SMB3 and later, enable better
performance, security and features, than would be possible with CIFS.
Note that when mounting to Samba, due to the CIFS POSIX extensions,
CIFS mounts can provide slightly better POSIX compatibility
than SMB3 mounts. SMB2/SMB3 mount options are also
slightly simpler (compared to CIFS) due to protocol improvements.

If you need to mount to Samba, Azure, Macs or Windows from this machine, say Y.

source code:

fs/smb/client/