How to disable SMB in Windows and Windows Server to avoid Ransomware WannaCry

For those who doesn't patch their Windows SMB is enable by default

This article describes how to enable and disable Server Message Block (SMB) version 1 (SMBv1), SMB version 2 (SMBv2), and SMB version 3 (SMBv3) on the SMB client and server components.

Warning: We do not recommend that you disable SMBv2 or SMBv3. Disable SMBv2 or SMBv3 only as a temporary troubleshooting measure. Do not leave SMBv2 or SMBv3 disabled.

In Windows 7 and Windows Server 2008 R2, disabling SMBv2 deactivates the following functionality:

Request compounding - allows for sending multiple SMB 2 requests as a single network request
Larger reads and writes - better use of faster networks
Caching of folder and file properties - clients keep local copies of folders and files
Durable handles - allow for connection to transparently reconnect to the server if there is a temporary disconnection
Improved message signing - HMAC SHA-256 replaces MD5 as hashing algorithm
Improved scalability for file sharing - number of users, shares, and open files per server greatly increased
Support for symbolic links
Client oplock leasing model - limits the data transferred between the client and server, improving performance on high-latency networks and increasing SMB server scalability
Large MTU support - for full use of 10-gigabye (GB) Ethernet
Improved energy efficiency - clients that have open files to a server can sleep

In Windows 8, Windows 8.1, Windows 10, Windows Server 2012, and Windows Server 2016, disabling SMBv3 deactivates the following functionality (and also the SMBv2 functionality that's described in the previous list):

Transparent Failover - clients reconnect without interruption to cluster nodes during maintenance or failover
Scale Out – concurrent access to shared data on all file cluster nodes
Multichannel - aggregation of network bandwidth and fault tolerance if multiple paths are available between client and server
SMB Direct – adds RDMA networking support for very high performance, with low latency and low CPU utilization
Encryption – Provides end-to-end encryption and protects from eavesdropping on untrustworthy networks
Directory Leasing - Improves application response times in branch offices through caching
Performance Optimizations - optimizations for small random read/write I/O