React Native Developer

Tuesday, February 19, 2019

COMPUTER NWTWORK


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Lab 2: 
Objective: To make the students aware about and learn the detailed use of the following OS level TCP/IP diagnostic and troubleshooting commands: ping, ns lookup

1)  Ping command

PING: Packet InterNet Groper ping
 

The ping command is a Command Prompt command used to test the ability of the source computer to reach a specified destination computer. The ping command is usually used as a simple way to verify that a computer can communicate over the network with another computer or network device.
The ping command operates by sending Internet Control Message Protocol (ICMP) Echo Request messages to the destination computer and waiting for a response. How many of those responses are returned, and how long it takes for them to return, are the two major pieces of information that the ping command provides.
For example, you might find that there are no responses when pinging a network printer, only to find out that the printer is offline and its cable needs replaced. Or maybe you need to ping a router to verify that your computer can connect to it, to eliminate it as a possible cause for a networking issue. Ping Command Syntax
ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS] [-r count] [-s count] [w timeout] [-R] [-S srcaddr] [-p] [-4] [-6] target [/?]
Ping Command Options
Item
Explanation
-t
Using this option will ping the target until you force it to stop by using Ctrl-C.
-a
This ping command option will resolve, if possible, the hostname of an IP address target.
-ncount
This option sets the number of ICMP Echo Requests to send, from 1 to 4294967295. The ping command will send 4 by default if -n isn't used.
-l size
Use this option to set the size, in bytes, of the echo request packet from 32 to 65,527. The ping command will send a 32-byte echo request if you don't use the -l option.
-f
Use this ping command option to prevent ICMP Echo Requests from being fragmented by routers between you and the target. The -f option is most often used to troubleshoot Path Maximum Transmission Unit (PMTU) issues.
-i TTL
This option sets the Time to Live (TTL) value, the maximum of which is 255.
-v TOS
This option allows you to set a Type of Service (TOS) value. Beginning in Windows 7, this option no longer functions but still exists for compatibility reasons.
-rcount
Use this ping command option to specify the number of hops between your computer and the target computer or device that you'd like to be recorded and displayed. The maximum value for count is 9, so use the tracert command instead if you're interested in viewing all the hops between two devices.
-scount
Use this option to report the time, in Internet Timestamp format, that each echo request is received and echo reply is sent. The maximum value for count is 4, meaning that only the first four hops can be time stamped.
-wtimeout
Specifying a timeout value when executing the ping command adjusts the amount of time, in milliseconds, that ping waits for each reply. If you don't use the -w option, the default timeout value of 4000 is used, which is 4 seconds.
-R
This option tells the ping command to trace the round trip path.
-Ssrcaddr
Use this option to specify the source address.
-p
Use this switch to ping a Hyper-V Network Virtualization provider address.
-4
This forces the ping command to use IPv4 only but is only necessary if target is a hostname and not an IP address.
-6
This forces the ping command to use IPv6 only but as with the -4option, is only necessary when pinging a hostname.
Target
This is the destination you wish to ping, either an IP address or a hostname.
/?
Use the help switch with the ping command to show detailed help about the command's several options.
EXAMPLE

ping –n 5 –l 1500 www.google.com

 

ping 127.0.0.1

 
 ping –a 192.168.1.22
 

Ping  -t  -6  localhost(servername)

 

ping –r 5 127.0.0.1 ping –r 9 127.0.0.1

 

2)nslookup

 
The nslookup (which stands for name server lookup) command is a network utility program used to obtain information about internet servers. It finds name server information for domains by querying the Domain Name System.
Most computer operating systems include a built-in command line program with the same name. Some network providers also host web-based services of this same utility (like Network-Tools.com). These programs are all designed to perform name server lookups against specified domains.
Displays information that you can use to diagnose Domain Name System (DNS) infrastructure. Before using this tool, you should be familiar with how DNS works. The nslookup command-line tool is available only if you have installed the TCP/IP protocol.

OPTIONS



Parameter
Description


exits nslookup.


Connects with the finger server on the current computer.


Displays a short summary of nslookup subcommands.


lists information for a DNS domain.


changes the default server to the specified DNS domain.


changes the default server to the server for the root of the DNS domain name space.


changes the default server to the specified DNS domain.


changes configuration settings that affect how lookups function.


prints the current values of the configuration settings.


changes the query class. The class specifies the protocol group



Parameter
Description



of the information.


Turns exhaustive Debugging mode on or off. All fields of every packet are printed.


Turns Debugging mode on or off.


nslookup /set defname
appends the default DNS domain name to a single component lookup request. A single component is a component that contains no periods.


changes the default DNS domain name to the name specified.


nslookup /set ignore
Ignores packet truncation errors.


changes the default TCP/UDP DNS name server port to the value specified.


changes the resource record type for the query.


Tells the DNS name server to query other servers if it does not have the information.


Sets the number of retries.


changes the name of the root server used for queries.


appends the DNS domain names in the DNS domain search list to the request until an answer is received. This applies when the set and the lookup request contain at least one period, but do not end with a trailing period.


changes the default DNS domain name and search list.


Parameter
Description


changes the initial number of seconds to wait for a reply to a request.


changes the resource record type for the query.


Specifies to use or not use a virtual circuit when sending requests to the server.

sorts and lists the output of the previous ls subcommand or commands.







SYNTAX
nslookup [-opt ...] [{Host| [Server]}
EXAMPLE
nslookup lifewire.com
 

nslookup www.microsoft.com

 









Lab 3:  
Objective: To make the students aware about and learn the detailed use of the following OS level TCP/IP diagnostic and troubleshooting commands: ipconfig, arp, netstat, tracert, telnet.

ipconfig(IP Configration)

In Windows, ipconfig is a console application designed to run from the Windows command prompt. This utility allows you to get the IP address information of a Windows computer. It also allows some control over active TCP/IP connections. ipconfig replaced the older winipcfg utility.
 


 









SYNTAX

ipconfig [/allcompartments] [/? | /all | /renew [adapter] | /release [adapter] | /renew6 [adapter] | /release6 [adapter] | /flushdns | /displaydns | /registerdns | /showclassid adapter | /setclassid adapter [classid] | /showclassid6 adapter | /setclassid6 adapter [classid] ]

OPTIONS
/all
Display full configuration information.
/release
Release the IPv4 address for the specified adapter.
/release6
Release the IPv6 address for the specified adapter.
/renew
Renew the IPv4 address for the specified adapter.
/renew6
Renew the IPv6 address for the specified adapter.
/flushdns
Purges the DNS Resolver cache.
/registerdns
Refreshes all DHCP leases and re-registers DNS names.
/displaydns
Display the contents of the DNS Resolver cache.
/showclassid
Displays all the DHCP class IDs allowed for adapter.
/setclassid
Modifies the DHCP class id.
/showclassid6
Displays all the IPv6 DHCP class IDs allowed for an adapter.
/setclassid6
Modifies the IPv6 DHCP class id.

EXAMPLE ipconfig/all

 

ipconfig/all| more


 

ipconfig/displaydns

 


arp
(AddressResolutionProtocol)

Address Resolution Protocols (ARP) deal with the way local IP addresses are resolved between computers on a network.
The ARP compares the address and subnet masks of the host and the target computer. If these match then the address has effectively been resolved to the local network.
 

Arp syntax

ARP -s inet_addreth_adr [if_addr]
ARP -d inet_addr [if_addr]
ARP -a [inet_addr] [-N if_addr]

OPTIONS

-a
Displays current ARP entries by interrogating the current protocol data. If inet_addr is specified, the IP and physical addresses for only the specified computer are displayed. If more than one network interface uses ARP, entries for each ARP table are displayed.
-g
Same as –a
inet_addr
Specifies an Internet address.
-N if addr
Displays the ARP entries for the network interface specified by if_addr.
-d
Deletes the host specified by inet_addr.
-s
Adds the host and associates the Internet address inet_addr with the physical

address eth_addr. The physical address is given as 6 hexadecimal bytes separated by hyphens. The entry is permanent.
eth_addr
Specifies a physical address.
if_addr
If present, this specifies the Internet address of the interface whose address translation table should be modified. If not present, the first applicable interface will be used.

EXAMPLE arp -a

 

netstat(NETworkSTATistics)

The netstat command is a Command Prompt command used to display very detailed information about how your computer is communicating with other computers or network devices.
Specifically, the netstat command can show details about individual network connections, overall and protocol-specific networking statistics, and much more, all of which could help troubleshoot certain kinds of networking issues.

 

 

 

 

 

 




SYNTAX

NETSTAT [-a] [-b] [-e] [-f] [-n] [-o] [-p proto] [-r] [-s] [-x] [-t] [interval]

OPTIONS


-a
Displays all connections and listening ports.
-b
Displays the executable involved in creating each connection or listening port. In some cases, well-known executables host multiple independent components, and in these cases, the sequence of components involved in creating the connection or listening port is displayed. In this case, the executable name is in [] at the bottom, on top is the component it called, and so forth until TCP/IP was reached. Note that this option can be time-consuming and will fail unless you have sufficient permissions.
-e
Displays Ethernet statistics. This option may be combined with the -s option.
-f
Displays Fully Qualified Domain Names (FQDN) for foreign addresses.
-n
Displays addresses and port numbers in numerical form.
-o
Displays the owning process ID associated with each connection.
-p proto
Shows connections for the protocol specified by proto; proto may be any of: TCP, UDP, TCPv6, or UDPv6. If used with the -s option to display per-protocol statistics, proto may be any of: IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, or UDPv6.
-r
Displays the routing table.
-s
Displays per-protocol statistics. By default, statistics are shown for IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, and UDPv6; the -p option may be used to specify a subset of the default.
-t
Displays the current connection offload state.
-x
Displays NetworkDirect connections, listeners, and shared endpoints.
-y
Displays the TCP connection template for all connections. Cannot be combined with the other options.
interval
Redisplays selected statistics, pausing interval seconds between each display. Press Ctrl+C to stop redisplaying statistics. If omitted, netstat will print the current configuration information once.

EXAMPLE

netstat –an

 

netstat 5

 

netstat –r

 

Tracert(TErminalNEtwork)

The tracert command is a Command Prompt command that's used to show several details about the path that a packet takes from the computer or device you're on to whatever destination you specify.
You might also sometimes see the tracert command referred to as the trace route command or traceroute command to install traceroutecommond in ubuntu sudo apt-get install traceroute
 





Tracert Command Syntax
tracert [-d] [-h MaxHops] [-w TimeOut] [-4] [-6] target [/?]

OPTIONS

Item
Description
-d
This option prevents tracert from resolving IP addresses to hostnames, often resulting in much faster results.
-
hMaxHops
This tracert option specifies the maximum number of hops in the search for the target. If you do not specify MaxHops, and a target has not been found by 30 hops, tracert will stop looking.
-wTimeOut
You can specify the time, in milliseconds, to allow each reply before timeout using this tracert option.
-4
This option forces tracert to use IPv4 only.
-6
This option forces tracert to use IPv6 only.
target
This is the destination, either an IP address or hostname.
/?
Use the help switch with the tracert command to show detailed help about the command's several options.

EXAMPLE trecert www.goole.com

 

tracert 192.168.1.1

 

tracert –d www.yahoo.com

 


Lab 4 a:
Objective:Implement a simple TCP socket based client server program in Python in which the client connects to the server. The server displays the ip address and port number of client and sendsan acknowledgement message back to client. The client displays the received acknowledgement message on screen.

Client.py

#!/usr/bin/env python3 

import socket 

HOST = '127.0.0.1'  # The server's hostname or IP address  PORT = 65432        # The port used by the server 

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:      s.connect((HOST, PORT)) 
    s.sendall(b'Hello, world')      data = s.recv(1024) 

print('Received', repr(data))

 






server.py

import socket 
HOST = '127.0.0.1'  # Standard loopback interface address (localhost) 
PORT = 65432        # Port to listen on (non-privileged ports are > 1023) 

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:      s.bind((HOST, PORT)) 
    s.listen(4)      conn, addr = s.accept()      with conn:          print('Connected by', addr)          while True: 
            data = conn.recv(1024)              if not data: 
                break              conn.sendall(data)
 


Lab 4 b:
Objective:Implement a simple UDP socket based client server program in Python in which the client connects to the server. The server displays the ip address and port number of client and sends an acknowledgement message back to client. The client displays the received acknowledgement message on screen.
Udp server

import socket  host = '127.0.0.1'  port = 6789 
Ssocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)  Ssocket.bind((host,port))  while True: 
            data,addr = Ssocket.recvfrom(1024)   print ("Message: ", data) 
socket.close() 
 

udp client

import socket  host = '127.0.0.1'  port = 6789 
msg = str.encode("hello server") 
Csocket = socket.socket(socket.AF_INET,socket.SOCK_DGRAM) 
Csocket.sendto(msg,(host,port))
 





















1.      List up to IO different protocols that appear in the protocol column in the unfiltered packet-listing
window.


2.      How long did it take from when the HTTP GET message was sent until the HTTP OK reply was received? (By default, the value of the Time column in the packet listing window is the amount of time, in seconds, since Wireshark tracing began. To display the Time field in time-of-day format, select the Wireshark View pull down menu, then select Time Display Format, then select Time-of-day. For now you don’t need to understand HTTP GET and OK, but reading the textbook may be helpful if you are curious on how they work.).

3.      What is the Internet address of the www.google.com? What is the Internet address of your computer? Include a screenshot and describe where you got the data to answer this question.


4.      Provide a screenshot showing http protocol only with Wireshark running on your computer.







5.      How many packets did you capture (total of all protocols, not just HTTP)? Now, use display filters to determine how many packets contain your ip address (hint: Use ip.addr instead of the clumsy ip.src or ip.dst format). What is this filter you used? Now, reverse the filter to determine how many packets don’t contain your ip address. See any problems here? If not, you've already figured out the point of this question, so explain how you did so. If so, how can this problem be fixed? What are the appropriate display filters to use? How does Wireshark warn you of such a problem?

























6.      Use your newly acquired Wireshark skills to capture the process when your browser loads the front page of INI's website (i.e. http://www.ini.cmu.edu). How many packets did you capture? Were all of them HTTP? How many HTTP requests did you make? Were all the replies "200 OK"? Did you find anything else interesting? Please ensure you have examined this packet capture in detail, using appropriate Wireshark functionality. Please include screen captures where you think they are necessary.

7.      What is the IP address of your computer? Of the gtu.ac.in server?




8.      What HTTP version is your browser running? What version of HTTP is the server running?

9.      What is the status code and phrase returned from the server to your browser?







10.   What languages does your browser indicate to the server that it can accept? Which header line is used to indicate this information?

11.   When was the HTML-file, that you have retrieved, last modified at the server? Which header line is used to indicate this information?





12.   How many bytes of content (size of file) are returned to your browser? Which header line is used to indicate this information?


























What is Wireshark?

Wireshark is a network packet analyzer. A network packet analyzer will try to capture network packets and tries to display that packet data as detailed as possible.
You could think of a network packet analyzer as a measuring device used to examine what’s going on inside a network cable, just like a voltmeter is used by an electrician to examine what’s going on inside an electric cable (but at a higher level, of course).
In the past, such tools were either very expensive, proprietary, or both. However, with the advent of Wireshark, all that has changed.
Wireshark is perhaps one of the best open source packet analyzers available today.

1.1.1. Some intended purposes

Here are some examples people use Wireshark for:
Network administrators use it to troubleshoot network problems
Network security engineers use it to examine security problems
QA engineers use it to verify network applications
Developers use it to debug protocol implementations
People use it to learn network protocol internals
Beside these examples Wireshark can be helpful in many other situations too.

1.1.2. Features

The following are some of the many features Wireshark provides:
Available for UNIX and Windows.
Capture live packet data from a network interface.
Open files containing packet data captured with tcpdump/WinDump, Wireshark, and a number of other packet capture programs.
Import packets from text files containing hex dumps of packet data.
Display packets with very detailed protocol information.
Save packet data captured.
Export some or all packets in a number of capture file formats.
Filter packets on many criteria.
Search for packets on many criteria.
Colorize packet display based on filters.
Create various statistics.
…​and a lot more!

Download Wireshark

To download Wireshark:
1.   Open a web browser.
2.   Navigate to http://www.wireshark.org.
3.   Select Download Wireshark.
4.   Select the Wireshark Windows Installer matching your system type, either 32-bit or 64-bit as determined in Activity 1. Save the program in the Downloads folder.
5.   Close the web browser.

Install Wireshark

Wireshark is a free and open source packet analyzer used for network troubleshooting and analysis. These activities will show you how to download and install Wireshark.
To install Wireshark:
1.   Open Windows Explorer.
2.   Select the Downloads folder.
3.   Locate the version of Wireshark you downloaded in Activity 2. Double-click on the file to open it.
4.   If you see a User Account Control dialog box, select Yes to allow the program to make changes to this computer.
5.   Select Next > to start the Setup Wizard.
6.   Review the license agreement. If you agree, select I Agree to continue.
7.   Select Next > to accept the default components.
8.   Select the shortcuts you would like to have created. Leave the file extensions selected. Select Next > to continue.
9.   Select Next > to accept the default install location.
10.                    Select Install to begin installation.
11.                    Select Next > to install WinPcap.
12.                    Select Next > to start the Setup Wizard.
13.                    Review the license agreement. If you agree, select I Agree to continue.
14.                    Select Install to begin installation.
15.                    Select Finish to complete the installation of WinPcap.
16.                    Select Next > to continue with the installation of Wireshark.
17.                    Select Finish to complete the installation of Wireshark.

 The Menu

Wireshark’s main menu is located either at the top of the main window (Windows, Linux) or at the top of your main screen (macOS). An example is shown in Figure 3.2, “The Menu”.

Note
Some menu items will be disabled (greyed out) if the corresponding feature isn’t available. For example, you cannot save a capture file if you haven’t captured or loaded any packets.
Figure 3.2. The Menu

The main menu contains the following items:
File: -
This menu contains items to open and merge capture files, save, print, or export capture files in whole or in part, and to quit the Wireshark application.
Edit: -
This menu contains items to find a packet, time reference or mark one or more packets, handle configuration profiles, and set your preferences; (cut, copy, and paste are not presently implemented).
View: -
This menu controls the display of the captured data, including colorization of packets, zooming the font, showing a packet in a separate window, expanding and collapsing trees in packet details.
Go: -
This menu contains items to go to a specific packet.
Capture: -
This menu allows you to start and stop captures and to edit capture filters.
Analyze: -
This menu contains items to manipulate display filters, enable or disable the dissection of protocols, configure user specified decodes and follow a TCP stream.
Statistics: -
This menu contains items to display various statistic windows, including a summary of the packets that have been captured, display protocol hierarchy statistics and much more.
Telephony: -
This menu contains items to display various telephony related statistic windows, including a media analysis, flow diagrams, display protocol hierarchy statistics and much more.
Wireless: -
The items in this menu show Bluetooth and IEEE 802.11 wireless statistics.
Tools: -
This menu contains various tools available in Wireshark, such as creating Firewall ACL Rules.
Help: -
This menu contains items to help the user, e.g. access to some basic help, manual pages of the various command line tools, online access to some of the webpages, and the usual about dialog.







INDUSTRIAL VISIT:

                                                                                                    Date:18/3/2019
                                                                                                    Monday
Industrial Visit MCA 2019 Thanks to Bhagwan mahavir college of Managemnet and our Proffesor and  the department of MCA, we the students of 4th semester MCA, were given the opportunity to go on an industrial visit to “Pure Skill IT Training Academy”. 
During Industrial visit students visit companies and get insight regarding the internal working environment of a company and how a company functions, as well as useful information related to the practical aspects of the educational course which cannot be visualized in lectures.
The industrial visit is considered one of the most tactical methods of teaching. It provides students with an opportunity to learn practically through interaction, working methods and employment practices. Moreover, it gives exposure from an academic point of view.

In Industrial Visit we got a knowledge about Wireshark ,how to use wireshark how we can work with wireshark and  we got knowledge about Networking that how the network works,how the switches were working in industry, and many wire and hubs are connected with many switches they saw us many types of cables which were used in Industry.
Industry Networks was very easy to use.

We Got some Knowledge About Networks in Industry:

1.Cable type: UTP – Twisted Pair Cable
2.Connector: RJ45
3.Switch: Ordinary 24 Port Fast Ethernet(gigabit) speed-1gbps
4.Topology: Star Topology
5.Router: Wireless Router,TP link company
6.Internet Connectivity: City BroadBand pure Fibre
7.Internet Speed: 100 mbps
8.Wifi Connectivity: Yes,by TP link wireless Router
9.Bandwidth: 100 mbps
10.ISP(Internet service provider): City Broadband
11.NIC card: Intel Company
12.IP: Class c
13.IP Address: 192.168.0.0
14.Licence Software: Microsoft Company





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