Transcript Some Network Commands - Texas Tech University

Some Network Commands
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Some useful network commands
– ping
– finger
– nslookup
– tracert
– ipconfig
Port Addresses
What is a port address?
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A unique number assigned to a network application
as an address to receive or send data.
Why need port addresses?
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A single host may run several servers, such as Web,
FTP, Telnet, Email, 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
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Port numbers are divided in three
ranges:
– Well-known ports: 0-1023, controlled by
IANA
– Registered ports: 1024-49151
– Dynamic or private ports: 49152-65535.
We also call them ephemeral ports.
Application Layer Port Addresses
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Default port number assignments
– Web: 80 (or 8080)
– FTP: 21
– News group: 119 (or 8119)
– Telnet: 23
– SMTP: 25
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IANA (Internet Assigned Numbers
Authority) is taking care this issue.
WINS
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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.
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.
WINS complements the NT Server's DHCP.
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
Windows Network Model
Internet Model
Application layer:
I/O
Named Pipes Mail Server
Environment Subsystem
FTP, TELNET,
HTTP, etc.
Transport layer:
TCP, UDP
Network layer: IP
Data link layer
Physical layer
Layer 7
Layer 6
Provider Interface
NetBIOS (Redirector)
TDI
NetBEUI
WINSOCK
Layer 5
Layer 4
TCP/IP
Layer 3
NDIS 3.0
NDIS Environment
and Drivers
802.2 802.3 802.4 802.5
NDIS: Network Driver Interface Specification
Layer 2
Layer 1
NDIS
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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)
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Created by IBM for its early PC Network, was adopted
by Microsoft, and has since become a de facto industry
standard.
A program that allows applications on different
computers to communicate within a local area network
(LAN).
Used in Ethernet, token ring, and Windows NT
networks.
NetBEUI
NetBEUI (NetBIOS Extended User Interface)
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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.
A new, extended version of NetBIOS, the program
that lets computers communicate within a local area
network.
Formalizes the frame format (or arrangement of
information in a data transmission) that was not
specified as part of NetBIOS.
NetBIOS vs. NetBEUI
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NetBIOS has 18 commands for PC
connections.
NetBEUI adds 8 more and is used as a
transport protocol. It is faster and more
efficient than NetBIOS
When NetBEUI is in use, NETBIOS becomes
API that invokes NetBeui.
They can support a LAN with less than 200
PCs.
NetBIOS over TCP/IP
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NetBIOS over TCP/IP runs over the TCP/IP, so that you
can share drives and printers over the Internet.
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.
With the installation of TCP/IP protocol, Windows
automatically installs the "NetBIOS over TCP/IP”.
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.