Windows 98 Remote Access Service Protocols

This article provides an overview of the communication, framing, and network protocols utilized by Remote Access Service (RAS) and Dial-Up Networking in Microsoft Windows 98. Operating during the height of the dial-up modem era, Windows 98 relied on an array of connection and transport protocols to authenticate users, establish secure sessions, and transmit local area network (LAN) traffic across remote telephone and serial lines.

Framing and Connection Protocols

Windows 98 RAS relied on data-link layer protocols to encapsulate network traffic across serial lines and modem connections.

  • Point-to-Point Protocol (PPP): PPP was the default and most widely used framing protocol in Windows 98 RAS. It provided a robust standard for connecting to remote servers, offering automatic configuration, error detection, support for multiple network protocols simultaneously, and encrypted authentication mechanisms.
  • Serial Line Internet Protocol (SLIP): Supported primarily for backward compatibility, SLIP was an older framing standard used to connect to legacy UNIX terminal servers. Unlike PPP, SLIP supported only TCP/IP, lacked dynamic IP address negotiation, and offered no native security or error correction.
  • Point-to-Point Tunneling Protocol (PPTP): Integrated into Windows 98 Dial-Up Networking, PPTP enabled Virtual Private Network (VPN) functionality. It allowed Windows 98 clients to establish secure, encrypted tunnels across the public Internet to access remote Windows NT networks by encapsulating PPP packets inside Generic Routing Encapsulation (GRE) headers.

Transport and Network Protocols

Once a remote connection was established via PPP or SLIP, Windows 98 RAS encapsulated several primary network protocols to enable file sharing, application access, and Internet browsing:

  • TCP/IP (Transmission Control Protocol/Internet Protocol): The standard protocol suite for accessing the Internet and modern corporate intranets. Windows 98 RAS supported both static IP configuration and dynamic addressing via DHCP (Dynamic Host Configuration Protocol) or PPP IPCP (IP Control Protocol).
  • IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange): Implemented via Microsoft’s NWLink, this protocol allowed remote Windows 98 clients to connect to Novell NetWare servers and access NetWare file and print resources over dial-up.
  • NetBEUI (NetBIOS Extended User Interface): A fast, non-routable protocol utilized for small, local Windows-based networks. RAS enabled remote access to NetBEUI-only Windows NT and Windows for Workgroups environments through NetBIOS gateways.

Authentication Protocols

To verify credentials and secure remote logins, Windows 98 RAS implemented several industry-standard authentication protocols over PPP:

  • PAP (Password Authentication Protocol): A basic authentication method that transmitted usernames and passwords in clear text.
  • CHAP (Challenge Handshake Authentication Protocol): A secure, encrypted challenge-response authentication scheme that prevented plain-text credential transmission.
  • MS-CHAP (Microsoft Challenge Handshake Authentication Protocol): Microsoft's proprietary extension of CHAP, designed to integrate with Windows NT domain security and support RSA RC4-based data encryption (MPPE, or Microsoft Point-to-Point Encryption).