Windows 2000 Services for UNIX File Sharing

Microsoft Windows 2000 executes cross-platform file sharing with UNIX and Linux systems using Microsoft Windows Services for UNIX (SFU), primarily through the implementation of Network File System (NFS) components and an identity-mapping service. By deploying Server for NFS, Client for NFS, and the User Name Mapping service, Windows 2000 bridges the fundamental protocol and security differences between Windows-based SMB/NTFS environments and UNIX-based NFS/POSIX architectures.

Server for NFS

Server for NFS allows a Windows 2000 machine to act as a native NFS server. When installed, an administrator can designate any local NTFS directory as an NFS share (export). UNIX clients mount these directories using standard NFS protocols (NFSv2 or NFSv3) over TCP/IP without requiring additional client-side software. Server for NFS processes incoming UNIX remote procedure calls (RPC) and translates them into Windows file system requests against NTFS.

Client for NFS

Client for NFS enables Windows 2000 workstations and servers to access directories exported by remote UNIX servers. Once installed, Client for NFS integrates directly with the Windows Multiple Provider Router (MPR) and network redirector. This integration allows users to mount remote UNIX file systems and interact with them as standard mapped network drives using familiar Windows utilities like Windows Explorer or the command line.

User Name Mapping

File systems in UNIX rely on numeric User Identifiers (UIDs) and Group Identifiers (GIDs), while Windows 2000 relies on Security Identifiers (SIDs) tied to local accounts or Active Directory. The User Name Mapping (UNM) service resolves this fundamental mismatch:

  • Identity Translation: UNM maps UNIX usernames, UIDs, and GIDs to their corresponding Windows domain or local accounts.
  • Data Sources: The service can pull UNIX account data directly from Network Information Service (NIS) servers or parse static UNIX /etc/passwd and /etc/group files.
  • Access Control: When a UNIX user requests a file on a Windows 2000 NFS share, Server for NFS queries the UNM service to determine the corresponding Windows SID. The request is then evaluated against the file's NTFS Access Control List (ACL), ensuring consistent security enforcement.

Permission and Metadata Translation

Windows 2000 SFU translates POSIX file permissions (read, write, execute for owner, group, and other) into NTFS discretionary access control lists (DACLs). When creating or modifying files, SFU recalculates these permissions to ensure parity across both operating systems:

  • POSIX Permissions on NTFS: Standard UNIX file mode bits are translated into equivalent NTFS read, write, and execute permissions.
  • Case Sensitivity: Because UNIX is case-sensitive and Windows is typically case-preserving but insensitive, SFU allows the Windows kernel to handle case-sensitive lookups on NTFS volumes configured for NFS sharing.