Network testing and debugging

Network Testing and
Debugging
TCP/IP CONCEPTS, WIRING, CONFIGURATING NETWORK, PROTOCOLS
S a d e e d A m e e n P O
s a d e e d a m e e n @ g m a i l . c o m

Testing and Debugging
 Testing activity is carried down to find the
defect in the network and its configurations.
 Identify and remove errors from computer
hardware or from network is termed as
debugging
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Possible points of failure
 The cable is plugged into the wrong network
 Host machine is plugged into the wrong network
 Host machine has a bad network card
 Machine is offline
 The web server may not be running
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Testing the IP configuration
 Windows systems offer a command-line tool,
called ipconfig, that lets you find out your
computer's IP configuration
 The output of this command gives the IP
configuration for each interface
 a computer with two network cards and one
wireless adapter has 3 interfaces each with its
own configuration
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Testing the IP configuration cont
 The Ethernet interface connected to the local area network (network card) is not
active since the cable is disconnected, but the PPP adapter (MTS) is configured.
 Machines on a same network must use a same address range (with different
addresses) and a same subnet mask
 In the case of a local network, connecting machines that do not have routable
IP addresses, so-called private address ranges must be used
 The default gateway refers to, when applicable, the IP address of the machine
offering internet access. DNS servers
 The DNS servers must correspond to the organization's DNS servers; most of the
time these are the service provider's DNS servers
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Testing the connection
 To test the proper functioning of a network
 Ping utility is a highly practical utility provided as a standard feature
with most operating systems.
 Ping lets you send a data packet to a network computer and lets
you evaluate the response time
 ping -t 192.168.0.3 Ping the IP addresses of the network's computers
 ping -t Mickey Ping the computer names
 Ping –t www.google.com ping a domain name
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Testing the connection cont
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Network Testing
 Load Testing
 Stress Testing
 Negative Testing
 Inopportune Testing
 Conformance/Compliance Testing
 Line Speed Testing
 Performance Testing
 Robustness/Security Testing
 Interoperability Testing 09-03-2015sadeedameen@gmail.com
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Load Testing
 Load testing is the process of putting demand on a system or device
and measuring its response. Load testing is performed to determine a
system's behavior under both normal and anticipated
peak loadconditions
 Where a system can support testing to actual volumes we have a
performance testing service to meet your requirements.
 Our network testing services provides comprehensive concurrent user
simulation of user and system traffic. This can be conducted while
concurrently generating threats and attacking traffic at high loads.
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Stress Testing
 Stress testing is a form of deliberately intense or thorough
testing used to determine the stability of a given nework.
 It involves testing beyond normal operational capacity,
often to a breaking point, in order to observe the results
 Stress testing is the process of determining the ability of a
network or device to maintain a certain level of
effectiveness under unfavorable conditions.
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Stress Testing
Actions involved may include:
 Running several resource-intensive applications in a single computer at
the same time
 Attempting to hack into a computer and use it as a zombie to
spreadspam
 Flooding a server with useless e-mail messages
 Making numerous, concurrent attempts to access a single Web site
 Attempting to infect a system with viruses, Trojans, spyware or
othermalware
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Negative Testing
 Process to verify that the device under test responds
correctly to error conditions or unacceptable input
conditions.
 Negative testing can be challenging because the
number of incorrect conditions is unlimited.
 Example of a negative test would be using a security
protocol for authentication with an incorrect parameter
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Inopportune Testing
 Process to verify that the device under test is able to
react properly when an unexpected event occurs
 The event is syntactically correct, but occurs when not
expected
 Inopportune testing is a specific instance of negative
protocol conformance testing.
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Conformance/Compliance Testing
 Testing both the capabilities and behavior of an implementation, and
checking what is observed against the conformance requirements in the
relevant International Standards.(ISO/IEC 9646-1:1994(E))
 testing to see if the device under test operates according to that
requirement
 This is done by creating a series of single function tests for each
requirement, resulting in thousands of tests
 An example of a conformance test is to check if the “ping” command
operates correctly.
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Line Speed Testing
 Process of verifying that a device can operate at its rated
line speed, when the bandwidth is 100% utilized or saturated.
 process of subjecting the device under test to out of
boundary conditions
 For example, if the device is rated as operating at 5 Giga
bytes per second, then the device should be able to handle
incoming traffic utilizing all the available bandwidth
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Performance Testing
 Process of verifying that the performance of the
device under test meets an acceptable level
 Performance testing is a superset of line speed
testing in which performance applies to many
aspects of a network device or application,
and not just line speed.
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Robustness/Security Testing
 Process of subjecting a device under test to particular input streams
 The input streams may be one of three types:
 Random input streams
 Valid input streams
 Invalid input streams
 Security testing is more broadly defined to include monitoring /
surveillance and the detection of specific exploits like IP spoofing or
phishing etc
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Interoperability Testing
 Process of testing devices from multiple manufacturers by interacting
in such a manner as to exercise the network protocol under test
 Interoperability testing is very useful in the early stages of a new
product
 As products mature, interoperability testing becomes less valuable as
it does not uncover enough new bugs to warrant the cost of setting
up, configuring and managing network equipment from various
manufacturers.
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Network Testing and Debugging
Penetration testing
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Penetration testing
 Evaluating the security of a network by hacking.
Basically, it is an analysis of system for any potential
vulnerabilities that may result from any of the following:
Poor or improper system configuration
Known and / or unknown hardware or software
flaws
Operational weaknesses in process
Technical countermeasures
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Penetration testing cont
Importance of PenetrationTesting:
 It prevents financial loss through from hackers or extortionists or
disgruntled employees
 It prevents financial loss through unreliable business systems and
processes
 From an operational perspective, penetration testing helps shape
information security strategy.
 It protects your brand by avoiding loss of consumer confidence
and business reputation.
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Basic Network Troubleshooting Tools
Ping
 The most commonly used network tool is the ping utility
 This utility is used to provide a basic connectivity test between the
requesting host and a destination host.
 This is done by using the Internet Control Message Protocol (ICMP)
which has the ability to send an echo packet to a destination host
and a mechanism to listen for a response from this host
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Tracert/traceroute
 once the ping utility has been used to determine basic
connectivity, the tracert/traceroute utility can used to determine
more specific information about the path to the destination host
 It includes the route the packet takes and the response time of
these intermediate hosts
 Tracert for Windows machines and traceroute for Linux/unix
based machines
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Tracert/traceroute cont
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Ipconfig/ifconfig
 The utilities that can be used to find out this IP configuration
information include the ipconfig utility on Windows machines and
the ifconfig utility on Linux/unix based machines.
 One of the most important things that must be completed when
troubleshooting a networking issue is to find out the specific IP
configuration of the variously affected hosts
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Ipconfig/ifconfig cont
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Nslookup
 Some of the most common networking issues revolve around issues with
Dynamic Name System (DNS) address resolution issues.
 The nslookup utility can be used to lookup the specific IP address(es)
associated with a domain name. If this utility is unable to resolve this
information, there is a DNS issue
 Along with simple lookup, the nslookup utility is able to query specific
DNS servers to determine an issue with the default DNS servers
configured on a host
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Nslookup cont
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Netstat
 the current state of the active network
connections on a host
 It is also possible to use the netstat utility to
determine which services on a host that is
associated with specific active ports
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PuTTY/Tera Term
 When connecting to a variety of different types of
equipment, a telnet, SSH or serial client is required; when
this is required both the puTTY and Tera Term programs are
able to provide these functionalities.
 The selection of one over the other is strictly a personal
preference.
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PuTTY/Tera Term cont
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Subnet and IP Calculator
 These can be used to unsure a correct IP address selection and with
this a correct IP address configuration
 While this type of tool is used by senior level network engineers, much of
the information obtained from the tool becomes simpler to calculate
the longer and more experience you have in the field
 Two of the more commonly used free IP calculators include
Wildpackets (Bitcricket) Network Calculator and Solarwinds Advanced
Subnet Calculator
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Subnet and IP Calculator cont
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Speedtest.net/pingtest.net
 A very easy test that can be used to both determine the Internet bandwidth
available to a specific host and to determine the quality of an Internet
connection is the use of the tools available at the speedtest.net and
pingtest.net websites
 The speedtest.net site provides the ability to determine the amount of
bandwidth that is available to a specific host at a specific point in time
 This is a good tool to use when measuring how long it is going to take to
upload or download information from a local to remote host
 The pingtest.net website is used to determine the quality of the connection by
measuring the ping response times and jitter amounts over a short period of
time. 09-03-2015sadeedameen@gmail.com
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Speedtest.net/pingtest.net cont
 This information can be used to determine a likelihood
of how well the measured connection will deal with
certain types of high demand traffic like Voice over IP
(VoIP) or gaming
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Pathping/mtr
 In an effort to take advantage of the benefits of both
the ping and tracert/traceroute commands, the
pathping and mtr utilities were developed
 Both of these tools take the functionality and
information that can be obtained from these types of
tools and provide a more detailed single picture of the
path characteristics from a specific host to a specific
destination
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Pathping/mtr->Pathping
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Pathping/mtr->mtr
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Route
This utility is used to display the current status of the routing table on a host
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Network testing and debugging

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