In the context of the Microsoft Windows NT line of operating systems, a Security Identifier (commonly abbreviated SID) is a unique name (an alphanumeric character string) which is assigned by a Windows Domain controller during the log on process that is used to identify a subject, such as a user or a group of users in a network of NT/2000 systems.

Windows grants or denies access and privileges to resources based on access control lists (ACLs), which use SIDs to uniquely identify users and their group memberships. When a user logs into a computer, an access token is generated that contains user and group SIDs and user privilege level. When a user requests access to a resource, the access token is checked against the ACL to permit or deny particular action on a particular object.

• 0 - Null Authority
• 1 - World Authority
• 2 - Local Authority
• 3 - Creator Authority
• 4 - Non-unique Authority
• 5 - NT Authority
• 9 - Resource Manager Authority

Setup Instruction:

http://supportkb.arraynetworks.net/kbcontent/AAA/UserSID/User_SID_Based_Login.ppt

Understanding SID:

http://supportkb.arraynetworks.net/kbcontent/AAA/UserSID/Security_Identifier.doc

http://supportkb.arraynetworks.net/kbcontent/AAA/UserSID/Why_Understanding_SIDs_is_Important.doc

Tools:

http://supportkb.arraynetworks.net/kbcontent/AAA/UserSID/Install-winMd5Sum.exe

http://supportkb.arraynetworks.net/kbcontent/AAA/UserSID/getsid.exe