Default File Sharing Protocols in Windows 98

Microsoft Windows 98 relied on a combination of application-level services and transport protocols to handle local network file sharing. At the core of this system was the Server Message Block (SMB) protocol operating through the NetBIOS API, with TCP/IP serving as the default underlying transport protocol. This article details the specific protocols, transport layers, and network components that Windows 98 utilized out of the box to share files and printers across local area networks.

Server Message Block (SMB)

The primary application-layer protocol for file sharing in Windows 98 was Server Message Block (SMB), specifically the dialect often referred to as CIFS (Common Internet File System). SMB enabled client computers to read, write, and request services from file and print shares hosted on other machines.

In Windows 98, this functionality was managed by the "File and printer sharing for Microsoft Networks" service, paired with the "Client for Microsoft Networks." While SMB handled the high-level file operations, it did not operate directly over raw IP; instead, it required an intermediary session service provided by NetBIOS.

NetBIOS (Network Basic Input/Output System)

NetBIOS served as the session and transport interface that SMB relied upon to establish connections, locate network resources, and manage machine names. Windows 98 utilized NetBIOS names (limited to 15 characters plus a 1-character service identifier) to identify computers on the local network rather than relying purely on DNS or hostnames.

Transport Protocols: NetBIOS over TCP/IP (NBT)

Unlike Windows 95, which originally defaulted to NetBEUI in its earliest retail releases, Windows 98 configured TCP/IP as its primary, default network protocol out of the box.

Because Windows 98 required NetBIOS for file sharing, it implemented NetBIOS over TCP/IP (NBT), standardized under RFC 1001 and RFC 1002. NBT enabled SMB file sharing to function across modern IP-routed networks using three specific standard ports:

  • UDP Port 137: NetBIOS Name Service (for name registration and resolution).
  • UDP Port 138: NetBIOS Datagram Service (for connectionless communication and browser elections).
  • TCP Port 139: NetBIOS Session Service (for establishing the connection used by SMB file transfers).

Windows 98 did not support direct-hosted SMB (SMB over raw TCP port 445), which was introduced later in Windows 2000; port 139 was strictly required.

Alternative Protocols Provided by Default

While TCP/IP was the default binding, Windows 98 included native, easily configurable support for legacy transport protocols to maintain backward compatibility:

  • NetBEUI (NetBIOS Extended User Interface): A fast, non-routable protocol designed for small, single-segment local area networks. It carried SMB traffic without the configuration overhead of IP addresses.
  • IPX/SPX-Compatible Protocol (NWLink): Microsoft’s implementation of Novell NetWare’s protocol stack. Windows 98 could run SMB over NetBIOS-over-IPX for environments integrated with Novell NetWare servers.