Some Network Commands n Some useful network commands –ping –finger –nslookup –tracert –ipconfig

Port Addresses What is a port address? n A unique number assigned to a network application as an address to receive or send data. Why need port addresses? n A single host may run several servers, such as Web, FTP, Telnet, , etc. When the network layer receives a message, it needs to know which application layer software package should receive the message.

Application Layer Port Addresses n Port numbers are divided in three ranges: –Well-known ports: , controlled by IANA –Registered ports: –Dynamic or private ports: We also call them ephemeral ports.

Application Layer Port Addresses n Default port number assignmentsport number assignments –Web: 80 (or 8080) –FTP: 21 –News group: 119 (or 8119) –Telnet: 23 –SMTP: 25 n IANA (Internet Assigned Numbers Authority) is taking care this issue.

WINS n WINS (Windows Internet Naming Service) manages the association of workstation names and locations with IP addresses without the user or an administrator having to be involved in each configuration change. n WINS automatically creates a computer name-IP address mapping entry in a table. When a computer is moved to another geographic location, the new subnet information will be updated automatically in the WINS table. n WINS complements the NT Server's DHCP. n WINS have been submitted to IETF as proposed open standards. New features are included in the follow-on to Windows NT, Windows 2000.

Windows Network Model Layer 7 Layer 6 Layer 5 Layer 4 Layer 3 Layer 2 Layer 1 Physical layer Data link layer Network layer: IP Transport layer: TCP, UDP Application layer: FTP, TELNET, HTTP, etc. Internet Model Windows Network Model I/O Named Pipes Mail Server Environment Subsystem NetBIOS (Redirector) TDI WINSOCK NDIS 3.0 NDIS Environment and Drivers NetBEUITCP/IP Provider Interface NDIS: Network Driver Interface Specification

NDIS n NDIS (Network Driver Interface Specification) is a Windows specification for how communication protocol programs (such as TCP/IP) and network device drivers should communicate with each other.

NetBIOS NetBIOS (Network Basic Input/Output System) n Created by IBM for its early PC Network, was adopted by Microsoft, and has since become a de facto industry standard. n A program that allows applications on different computers to communicate within a local area network (LAN). n Used in Ethernet, token ring, and Windows NT networks.

NetBEUI NetBEUI (NetBIOS Extended User Interface) n Developed by IBM for its LAN Manager product and has been adopted by Microsoft for its Windows NT, LAN Manager, and Windows for Workgroups products. n A new, extended version of NetBIOS, the program that lets computers communicate within a local area network. n Formalizes the frame format (or arrangement of information in a data transmission) that was not specified as part of NetBIOS.

NetBIOS vs. NetBEUI n NetBIOS has 18 commands for PC connections. n NetBEUI adds 8 more and is used as a transport protocol. It is faster and more efficient than NetBIOS n When NetBEUI is in use, NETBIOS becomes API that invokes NetBeui. n They can support a LAN with less than 200 PCs.

NetBIOS over TCP/IP n NetBIOS over TCP/IP runs over the TCP/IP, so that you can share drives and printers over the Internet. n In the "Network" configuration window in Windows 95, there is no option for NetBIOS over TCP/IP, but a "NetBEUI" entry, with which Microsoft actually means NetBIOS over NetBEUI. n With the installation of TCP/IP protocol, Windows automatically installs the "NetBIOS over TCP/IP”. n If you do want the TCP/IP protocol, but not "NetBIOS over TCP/IP" (because of security problem), you should uncheck "Files and Printer Sharing" in the Bindings tab of the TCP/IP entry in Network Configuration.