Chapter%20Overview

1
Chapter Overview

• TCP/IP Services
• TCP/IP Utilities

2
Automated TCP/IP Configuration Solutions

• Reverse Address Resolution Protocol (RARP)
• Bootstrap Protocol (BOOTP)
• Dynamic Host Configuration Protocol (DHCP)

3
RARP

• Uses the same message format as Address
  Resolution Protocol (ARP)
• Designed for diskless workstations
• Supplies an Internet Protocol (IP) address only
• No longer used

4
RARP Communications
5
BOOTP

• Supplies an IP address and other Transmission
  Control Protocol/Internet Protocol (TCP/IP)
  parameters
• Can supply an executable boot file using Trivial
  File Transfer Protocol (TFTP)
• Requires you to manually configure parameters for
  each client
• Cannot allocate IP addresses automatically
• Cannot prevent IP address duplication

6
DHCP

• Addresses the shortcomings of RARP and BOOTP
• Dynamically allocates IP addresses from a pool
• Reclaims unused addresses
• Prevents IP address duplication
• Supplies all TCP/IP parameters

7
DHCP Components

• Client
• Server
• Protocol

8
DHCP Address Allocation Types

• Manual allocation
• Automatic allocation
• Dynamic allocation

9
Manual Allocation

• The administrator assigns a permanent IP address
  to the client.
• Manual allocation is used for computers that
  require permanent IP address assignments.

10
Automatic Allocation

• The DHCP server assigns the client a permanent IP
  address chosen from a pool.
• Automatic allocation is used on networks where
  computers are rarely moved to other subnets.
• This minimizes DHCP traffic.

11
Dynamic Allocation

• The DHCP server leases to the client an IP
  address chosen from a pool.
• The client must periodically renew the lease
  address.
• Unrenewed lease addresses are returned to the
  pool.
• Dynamic allocation allows you to add, remove, and
  relocate computers.

12
The DHCP Message Format
13
The DHCP Options Field Format
14
DHCP Message Types

• 1DHCPDISCOVER
• 2DHCPOFFER
• 3DHCPREQUEST
• 4DHCPDECLINE
• 5DHCPACK
• 6DHCPNAK
• 7DHCPRELEASE
• 8DHCPINFORM

15
The DHCP Address Assignment Process
16
The IP Address Leasing Process

• The address assignment process is the same for
  all of the allocation methods.
• Clients using manual or automatic allocation
  receive no further communication after the
  address assignment.
• Clients using dynamic allocation lease IP
  addresses for a time interval specified by the
  server.
• The client must renew the lease on a regular
  basis to continue using it.
• DHCP address leases are typically measured in
  days.
• If addresses are in short supply, a shorter lease
  interval is warranted.
• If computers are rarely moved to other subnets,
  longer lease intervals reduce the DHCP traffic.

17
The DHCP Lease Renewal Process
18
The HOSTS File

• A HOSTS file is a lookup table containing a list
  of host names and their equivalent IP addresses.
• Each computer has its own HOSTS file.
• As the Internet grew, the HOSTS file became
  impractical, and the Domain Name System (DNS)
  eventually replaced it.

19
DNS Characteristics

• Defined in Request for Comments (RFC) 1034 and
  RFC 1035
• DNS defines
• A hierarchical namespace for computer networks
• A service for resolving names into IP addresses

20
The DNS Namespace
21
The DNS Name Resolution Process
22
DNS Resource Record Types
Record Type Function
Start of Authority (SOA) Indicates that the name server is the authoritative source for the domain
Name Server (NS) Identifies the DNS servers in the domain
Address (A) Contains a name-to-address mapping for a computer in the domain
Canonical Name (CNAME) Creates an alternative (or alias) name for a computer already represented by an Address record
Pointer (PTR) Contains an address-to-name mapping in in-addr.arpa for a computer in the domain
Mail Exchange (MX) Identifies a computer that is responsible for processing e-mail traffic addressed to the domain
23
WINS Characteristics

• Is the acronym for Windows Internet Name Service
• Is a Network Basic Input/Output System (NetBIOS)
  name server
• Resolves NetBIOS names into IP addresses
• Used only by Microsoft Windows computers

24
Ping Characteristics

• Supplied with virtually every TCP/IP
  implementation
• Tests connectivity to another TCP/IP system
• Syntax ping target

25
Ping Output (Typical)

• Pinging cz1 192.168.2.10 with 32 bytes of
  data 
• Reply from 192.168.2.10 bytes32 timelt10ms
  TTL128
• Reply from 192.168.2.10 bytes32 timelt10ms
  TTL128
• Reply from 192.168.2.10 bytes32 timelt10ms
  TTL128
• Reply from 192.168.2.10 bytes32 timelt10ms
  TTL128
• Ping statistics for 192.168.2.10Packets Sent
  4, Received 4, Lost 0 (0 loss),
• Approximate round trip times in
  milli-secondsMinimum 0ms, Maximum 0ms,
  Average 0ms

26
Traceroute Characteristics

• Variant of the Ping program
• Displays a list of the routers on the path that
  packets take to a destination
• Uses Echo Request and Echo Reply messages, as
  Ping does
• Modifies the Time To Live value in each
  successive Echo Request message
• Can be used to troubleshoot network
  communications problems by specifying the
  location of the difficulty

27
IPCONFIG.EXE and WINIPCFG.EXE Characteristics

• IPCONFIG.EXE and WINIPCFG.EXE are Windows
  utilities that display TCP/IP configuration
  parameters.
• Use IPCONFIG.EXE on Microsoft Windows 2000 and
  Microsoft Windows NT.
• Use WINIPCFG.EXE on Microsoft Windows 95,
  Microsoft Windows 98, and Microsoft Windows Me.
• Both utilities can release and renew DHCP IP
  addresses.

28
ARP.EXE Characteristics

• ARP.EXE enables you to view and modify the
  contents of the ARP cache.
• Adding addresses to the ARP cache speeds up the
  connection process.
• Addresses added manually to the ARP cache are not
  purged.

29
Using ARP.EXE

• Syntax
• ARP -a ipaddress -n ipaddress -s
  ipaddress hwaddress interface -d ipaddress
  interface

Parameter Function
-a ipaddress Displays the contents of a specific ARP cache entry
-n ipaddress Displays the contents of the ARP cache for a network interface
-s ipaddress hwaddress interface  Adds a new entry to the ARP cache
-d ipaddress interface Deletes an entry in the ARP cache
30
Using NETSTAT.EXE

• Syntax
• NETSTAT interval -a -p protocol -n -e
  -r -s

Parameter Function
interval Refreshes the display every interval seconds
-a  Displays the current network connections and the ports that are currently listening for incoming network connections
-p protocol   Displays the currently active connections for the protocol specified by the protocol variable
-n Causes the program to identify computers using IP addresses instead of names
-e  Displays incoming and outgoing traffic statistics for the network interface
-r  Displays the routing table plus the current active connections
-s   Displays detailed network traffic statistics for the IP, Internet Control Message Protocol (ICMP), TCP, and User Datagram Protocol (UDP) protocols
31
Using NBTSTAT.EXE

• Syntax
• NBTSTAT -a name -A ipaddress -c -n
  -r -R -s -S -RR

Parameter Function
-a name Displays the NetBIOS names registered on the computer identified by the name variable
-A ipaddress  Displays the NetBIOS names registered on the computer identified by the ipaddress variable
-c  Displays the contents of the local computer's NetBIOS name cache
-n  Displays the NetBIOS names registered on the local computer
-r Displays the number of NetBIOS names registered and resolved by the local computer, using both broadcasts and WINS
32
Using NBTSTAT.EXE (Cont.)

• Syntax
• NBTSTAT -a name -A ipaddress -c -n -r
  -R -s -S -RR

Parameter Function
-R Purges the local computer's NetBIOS name cache of all entries and reloads the LMHOSTS file
-s Displays a list of the computer's currently active NetBIOS settings (identifying remote computers by name), their current status, and the amount of data transmitted to and received from each system
-S Displays a list of the computer's currently active NetBIOS settings (identifying remote computers by IP address), their current status, and the amount of data transmitted to and received from each system
-RR Sends name release requests to WINS, then starts refresh
33
Nslookup Syntax

• Syntax
• NSLOOKUP DNSname DNSserver

Parameter Function
DNSname Specifies the DNS name that you want to resolve
DNSserver Specifies the DNS name or IP address of the DNS server that you want to query for the name specified in the DNSname variable
34
Telnet

• Telnet provides remote control capabilities.
• Telnet clients can execute commands on a server
  and view the results.
• Telnet was designed for UNIX systems.
• All Windows versions include a Telnet client.
• Windows 2000 and later versions have a Telnet
  server.

35
FTP

• You can use the File Transfer Protocol (FTP) to
  transfer files between computers, create and
  remove directories, rename and delete files, and
  manage access permissions.
• FTP was designed for UNIX computers.
• FTP is the mainstay of Internet communications.
• All UNIX computers have FTP client and server
  capabilities.
• All Windows computers have a command-line FTP
  client.
• Windows 2000 and Windows NT servers have an FTP
  server built into Microsoft Internet Information
  Services (IIS).

36
Chapter Summary

• TCP/IP services
• DHCP assigns IP addresses by using automatic,
  manual, or dynamic allocation.
• DNS resolves host and domain names into IP
  addresses.
• WINS resolves NetBIOS names into IP addresses.
• TCP/IP utilities
• Ping tests whether one computer running TCP/IP
  can communicate with another computer on the
  network.
• Traceroute displays the path that packets take
  through a network to reach their destinations.
• IPCONFIG.EXE and WINIPCFG.EXE display information
  about the computers TCP/IP configuration, and
  they release and renew DHCP IP address
  assignments.

37
Chapter Summary (Cont.)

• TCP/IP utilities (Cont.)
• ARP.EXE enables you to view and modify the
  contents of the ARP cache maintained by a TCP/IP
  system.
• Netstat displays information about a computers
  TCP/IP connections and the traffic passing over
  them.
• NBTSTAT.EXE displays information about NetBIOS
  connections and their traffic.
• Nslookup enables you to transmit DNS requests to
  specific servers.
• Telnet provides remote control access to another
  computer on the network.
• FTP lets you manage files and transfer them to
  and from a remote computer.