2016-12-05 WINDOWS NETWORKS AND NAMES NetBIOS and NetBEUI • 1983: IBM’s PC-LAN networks uses NetBIOS - API (Application Programmer Interface) only - relies on other network protocols • Corresponds to Session layer of OSI model/netbeui • NetBIOS API provides: - Name registration, resolution service - Connection-oriented session service - Connectionless Datagram service • NetBEUI – NetBIOS services over IEEE 802.2 frames - not used anymore 1 2016-12-05 NetBIOS Over TCP/IP - NBT • supports NetBIOS connections on TCP/IP networks - Sometimes called “NetBEUI” or “NetBIOS” (oops) • 1987: RFCs 1001, 1002 • Uses well-known TCP and UDP ports: - port 137 - NetBIOS Name Service, NBNS » generally uses UDP - port 138 - NetBIOS Datagram Service » generally uses UDP - port 139 - NetBIOS Session Service » generally uses TCP » short sessions - port 445 - SMB exchanges NetBIOS, NetBEUI, and OSI • matched to OSI • Redirector - sends network requests to layers: appropriate server - 7 – Redirector • SMB - 6 – SMB - file and printer sharing » replaced by CIFS • NetBIOS - session, datagram, and name - 5 – NetBIOS services - 4 –(NetBEUI) • NetBEUI - 3 –(NetBEUI) - data transport, frame formatting - 2 – NDIS – works with NetBIOS » Network Driver Interface Specification • NDIS - MS interface to NICs - 1 – NIC 2 2016-12-05 SMB/CIFS Networking • Servers broadcast their name, advertise services - Entire group/domain sees broadcast • Windows Workgroup - Organizes computers into groups that can share - “My Network Places” folder on a Windows machine - Any node can join by choosing the workgroup name - Non-Windows nodes: Samba software provides CIFS support • Windows Domain - Based on a domain controller node, running Windows Server - Nodes must authenticate to the domain controller to join - All domain controllers are also DNS servers • Active Directory - Distributed organization of domain controllers NetBIOS Names • NetBIOS names are “flat” – no extension or suffix - Maximum length of 16 octets » MS: 15 characters for name, 16th octet gives node type - Disallowed characters are \ / : * ? " ; | and SPACE - Distinct from computer’s name, but usually set equal - Case-insensitive: “abcd”, “aBcD”, and “ABCD” are all the same name 3 2016-12-05 Windows Names NetBIOS Names • Original scheme: Windows host broadcasts its name at startup - This registers the name on the local network - Clients can also broadcast to look for servers • WINS: Windows Internet Name Service takes the place of broadcasts - More efficient 4 2016-12-05 Server Message Block • Application-layer protocol - Primarily for use on local networks • Uses TCP port 445 • Can also use NetBIOS via UDP ports 137 & 138 or TCP ports 137 & 139 • SMB and CIFS share files/folders and printers, based on NetBIOS names - Server Message Block – original protocol, used by Microsoft - Common Internet File System – current, cross-platform version • SAMBA - open-source implementation of SMB Wireshark – Windows Name Broadcast 5 2016-12-05 Windows Networking in the VM-LAN • Start your Linux client - Start Wireshark - Set the display filter as: (udp.port>=137 && udp.port<=139) • Start your Windows client - You should see NBNS and BROWSER frames in wireshark Active Directory and Integrated Zones • Standard DNS keeps a primary zone file on a domain’s primary DNS server - Secondary DNS servers mirror it with secondary zone files - Only the primary zone records can be updated • Active Directory-integrated zone allows all domain controllers to update DNS records - DHCP servers, new IP nodes can submit updates to one of the DNS servers 6 2016-12-05 LMHOSTS, WINS Servers and Proxies • LMHOSTS file on a client node - Text file, keeps listings of other NetBIOS nodes - Similar to DNS hosts file • WINS servers - Windows Internet Name Service - Maintain records of NetBIOS names - Clients register directly with WINS server instead of broadcasting - Can accept routed registrations • WINS proxy agents - Forward broadcast NetBIOS names to a WINS server - Needed to support nodes that don’t know about WINS servers WINS and TCP/IP • Windows 7 Advanced TCP/IP settings dialog • Use and configuration of WINS server and LMHOSTS file are managed here 7.