LAN Manager
Encyclopedia
LAN Manager was a Network Operating System
(NOS) available from multiple vendors and developed by Microsoft
in cooperation with 3Com Corporation. It was designed to succeed 3Com's 3+Share
network server software which ran atop a heavily modified version of MS-DOS
.
operating system co-developed by IBM
and Microsoft. It originally used the Server Message Block
protocol atop either the NetBIOS Frames protocol (NBF) or a specialized version of the Xerox Network Systems (XNS) protocol. These legacy protocols had been inherited from previous products such as MS-NET for MS-DOS
, Xenix-NET for MS-Xenix
, and the afore-mentioned 3+Share. A version of LAN Manager for Unix-based systems called LAN Manager/X was also available.
In 1990, Microsoft announced LAN Manager 2.0 with a host of improvements, including support for TCP/IP as a transport protocol. The last version LAN Manager, 2.2, which included an MS-OS/2 1.31 base operating system, remained Microsoft's strategic server system until the release of Windows NT Advanced Server
in 1993.
Many vendors shipped licensed versions, including:
a user's password
known as the LM hash
algorithm. This makes the authentication crackable in a matter of seconds using rainbow table
s or in few hours using brute force. Its use in Windows NT
was replaced by NTLM
, which is still vulnerable to rainbow tables, but less vulnerable to brute force attacks. Both protocols have subsequently been deprecated in favor of Kerberos, but remain in use for backward compatibility and inter-operability.
Network operating system
A networking operating system , also referred to as the Dialoguer, is the software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions...
(NOS) available from multiple vendors and developed by Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
in cooperation with 3Com Corporation. It was designed to succeed 3Com's 3+Share
3+Share
3+Share was a pioneering file and print sharing product from 3Com. Introduced in the early 1980s, 3+Share was competitive with Novell's NetWare in the open systems network server business throughout the 1980s....
network server software which ran atop a heavily modified version of MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
.
Development history
LAN Manager was based on the OS/2OS/2
OS/2 is a computer operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for "Operating System/2," because it was introduced as part of the same generation change release as IBM's "Personal System/2 " line of second-generation personal...
operating system co-developed by IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
and Microsoft. It originally used the Server Message Block
Server Message Block
In computer networking, Server Message Block , also known as Common Internet File System operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an...
protocol atop either the NetBIOS Frames protocol (NBF) or a specialized version of the Xerox Network Systems (XNS) protocol. These legacy protocols had been inherited from previous products such as MS-NET for MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
, Xenix-NET for MS-Xenix
Xenix
Xenix is a version of the Unix operating system, licensed to Microsoft from AT&T in the late 1970s. The Santa Cruz Operation later acquired exclusive rights to the software, and eventually superseded it with SCO UNIX ....
, and the afore-mentioned 3+Share. A version of LAN Manager for Unix-based systems called LAN Manager/X was also available.
In 1990, Microsoft announced LAN Manager 2.0 with a host of improvements, including support for TCP/IP as a transport protocol. The last version LAN Manager, 2.2, which included an MS-OS/2 1.31 base operating system, remained Microsoft's strategic server system until the release of Windows NT Advanced Server
Windows NT 3.1
Windows NT 3.1 is the first release of Microsoft's Windows NT line of server and business desktop operating systems, and was released to manufacturing on 27 July 1993. The version number was chosen to match the one of Windows 3.1, the then-latest operating environment from Microsoft, on account of...
in 1993.
Many vendors shipped licensed versions, including:
- 3Com Corporation 3+Open
- HP LAN Manager/X
- IBMIBMInternational Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
LAN ServerLAN ServerIBM LAN Server started as a close cousin of Microsoft LAN Manager and first shipped in early 1988. It was originally designed to run on top of Operating System/2 Extended Edition. The network client was called IBM LAN Requester and was included with OS/2 EE 1.1 by default. IBM LAN Server started as... - Tapestry Torus
Security vulnerability
LAN Manager authentication uses a particularly weak method of hashingCryptographic hash function
A cryptographic hash function is a deterministic procedure that takes an arbitrary block of data and returns a fixed-size bit string, the hash value, such that an accidental or intentional change to the data will change the hash value...
a user's password
Password
A password is a secret word or string of characters that is used for authentication, to prove identity or gain access to a resource . The password should be kept secret from those not allowed access....
known as the LM hash
LM hash
LM hash, LanMan, or LAN Manager hash was the primary hash that Microsoft LAN Manager and Microsoft Windows versions prior to Windows NT used to store user passwords...
algorithm. This makes the authentication crackable in a matter of seconds using rainbow table
Rainbow table
A rainbow table is a precomputed table for reversing cryptographic hash functions, usually for cracking password hashes. Tables are usually used in recovering the plaintext password, up to a certain length consisting of a limited set of characters. It is a form of time-memory tradeoff, using less...
s or in few hours using brute force. Its use in Windows NT
Windows NT
Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix. It was intended to complement...
was replaced by NTLM
NTLM
In a Windows network, NTLM is a suite of Microsoft security protocols that provides authentication, integrity, and confidentiality to users....
, which is still vulnerable to rainbow tables, but less vulnerable to brute force attacks. Both protocols have subsequently been deprecated in favor of Kerberos, but remain in use for backward compatibility and inter-operability.