How to be a network adminstrator (2)

We will begin  network admin package 2 , Check the first package here :

 Agenda for this package :

• $$ netstat
• $$ ifstat
• $$ tcpdump
• $$ dhclient
• $$ nmap
• $$ telnet
• $$ ssh
• $$ minicom
• $$ ftp
• $$ wget
• $$ showmount

 

1- netstat

• ** Function : used to display network connections , information , else ..
• ** Syntax :

$netstat [option]

hint : option like [-r] [-s] ,make view of info page

 

example

 

netstat without options used to display all active localhost connections.

 

2- ifstat

• ** Function : a simple tool to report interface activity
• ** Syntax :

$ifstat

example

• ifstat need to install may be by default with system if not make this
  ◦ sudo apt-get install ifstat for debian
  ◦ yum install ifstat

 

3- tcpdump

• ** Function : tcpdump command is also called as packet analyzer . With tcpdump allow us to capture packets , then we can use it in analyziz ,we can save it in fie with extension .pcap
• ** syntax :

$tcpdump [option] [argument such as file name with extension type]

 

example

may be say that you don’t have perrmission fot that

• $ type su
• $ tcpdump -i eth0   #network interface

• making tcpdump files

◦ tcpdump -w test.pcap -i eth0

just after this make ls command and see that will make afile called  test.pcap

 

4- dhclient :

• ** Function : Dynamic Host Configuration Protocol Client , what !!!

it  provides a means for configuring one or more network interfaces using the Dynamic Host Configuration Protocol

 

• ** Syntax :

# dhclient [optiom] [argument]

 

example :
from abilities of dhclient that its can renews the ip address

• ** su
• ** dhclient eth0                #eth0 (my network interface)

 

 

5- nmap : (Short for network mapper)

• $ Function :  nmap is a network exploration tool and security
• $ used as port scanner , so what is the mean of port scanner !
•  
• $ Port scanner : A software program designed to go through a large listing of interesting ports or all available network ports and probe each port to see if it is available or open and accepting packets.

 

I am not good an asecurity guy so I am not good at this point , but let’s do some with this

 

• example :

 

notice PORT and STATE .

 

 

6- telnet :

Function : we can use telnet tool to connect to another remote computer .

• Syntax :

# telnet  [ server name for example ]

this will ask u for >>

                                    username :

                                    password :

 

 

7- ssh : ( secure shell )

• # Function : is an encrypted protocol and associated program intended to replace telnet . It can also be used for creating secure tunnels .
• # Syntax :

# ssh [ server name for example]

 

8- minicom

• # Function : used to connect to serial device such as router and servers such as cisco router for example .

           #  Syntax  :

 minicom >>>> make connection with default serial device

minicom -s Edit minicom settings

 

 

9- ftp : ( file transfer protocol )

• ** Function : is commonly used for copying files to and from other computers. These computers may be at the same site or at different sites thousands of miles apart.

• ** Syntax :

$ftp [option] [host]

when type this this will open a shell begin with ftp> we can make ftp command

 

• this is the list of available command for ftp

 

10 – wget : File download utility for Linux systems

• ** Function : is a file download utility for the command line. It can be used to download files via HTTP and FTP protocols. In the above example, a file is downloaded from a

remote HTTP system and saved in the current directory.

• ** Syntax :

examples

▪                     wget http://%5BHOST/FILE%5D

▪                     wget ftp://[HOST/FILE]

 

 

كيف يعمل البلوتوث ؟

تعود تسميه البلوتوث الى ملك الدنمارك هارالد بلوتوث الذى قد نجح فى توحيد الدنمارك وجزء من النرويج الى مملكه واحده كما انه ادخل الديانه المسيحيه للدنمارك وقد قتل عام 986 فى معركه مع ابنه سفين وعلى الرغم من انه اسم ليس له صله بالتكنولوجيا الا انه قد اختير للدلاله على وجود شركات هامه فى مجال صناعه الاتصالات فى منطقه البحر البطليق ( بما فى ذلك من الدنمارك والسويد وفنلندا والنرويج)

وقد تم تصميم تقنية بلوتوث في المقام الأول لدعم الشبكات اللاسلكية فتلك الاشارات تغطي مسافات قصيرة وعادة ما يصل الى 32 قدما (10 مترا) و توجد إصدارات متعددة منها الإصدار 1.1 حيث معدل نقل البيانات1 Mbps والاصدار 1.2 كما يوجد الاصدار 2.0.الذى يبلغ فيه معدل نقل البيانات الى اكثر من 3 Mbps  والاجهزه التى بها اصدار 2.0 يمكنها التعامل مع الاصدارات الاخرى اى ان غالبا ما يتم التعامل لمعدل نقل البيانات 1 Mbps

تقوم شبكه البلوتوث بنقل البيانات عبر موجات منخفضه فى ال(power) حيث يصل التردد الى 2.45GH كما يمكن للبلوتوث ان يتصل ب 8 اجهزه فى نفس الوقت ولذلك قد يتسائل البعض عن كيفيه نقل البيانات البعض دون حدوث تداخل فى الاشارات؟؟ وهل تلك اشاره البلوتوث تؤثر على اشاره المحمول والعكس ؟؟

بالطبع لا حيث ان اشاره البلوتوث تصل الى 1mw اذا ما قورنت باشارات المحمول التى تصل الى 3w & 4w مما يجعل تلك الاشارات ضعيفه ولكنها كافيه لاختراق الجدران كل ذلك فى نطاق 10m كما يوجد مسح متواصل لمدى ترددات اشارة البلوتوث وهذا مايعرف باسم spread-spectrum frequency hopping حيث أن المدى المخصص لترددات البلوتوث هي بين GH2.40 إلى GH2.48 ويتم هذا المسح بمعدل 1600 مرة في الثانية الواحدة وهذا ما يجعل الجهاز المرسل يستخدم تردد معين مثل GH2.42  لتبادل المعلومات مع جهاز أخر في حين أن جهازين في نفس الغرفة يستخدموا تردد آخر مثل  GH2.45  ويتم اختيار هذه الترددات تلقائيا وبطريقة عشوائية مما يمنع حدوث تداخلات بين الاجهزة، لانه لا يوجد اكثر من جهازين يستخدما نفس التردد في نفس الوقت واذا حدث تداخل فيكون لجزء من الثانيه ولن تشعر به.

والسؤال الان اذا تواجد فى المنزل اجهزه كثيره تعمل بالبلوتوث مثلا كالمحمول و الريسيفر وكمبيوتر وغيرهم كيف ستعمل تلك الاجهزه ؟؟ عندما تكون الاجهزة مزودة بتكنولوجيا البلوتوث فإن هذه الاجهزة تتمكن من معرفة المطلوب منها دون تدخل من المستخدم فشرائح البلوتوث تكون مبرمجه بكل المعلومات الازمه لتشغيلها حيث يمكنها الاتصال فيما بينها فتعرف فيما اذا كان مطلوب منها نقل بيانات مثل بيانات البريد الالكتروني من جهاز الهاتف المحمول إلى الكمبيوتر أو التحكم بأجهزة أخرى مثل تحكم جهاز الستيريو بالسماعات. حيث تنشئ شبكة تواصل صغيرة بين الأجهزة وتوابعها تعرف باسم personal-area network  وتختصر PAN أو باسم  piconet تستخدم كل شبكة احد الترددات المتوفرة في المدى من 2.40 GH إلى.48 GH2 وتلك الشبكه تكون لها (IP Address) خاص بها وبالتالى يتم نقل البيانات داخل تلك الشبكه فقط اما اشارات الاجهزه المجاوره لا تتأثر بها.

ولكن يوجد الثغرات الامنيه فى ذلك النظام فقد تمكن بعض الاشخاص من التجسس والتصنت على المكالمات لبعض من الاشخاص ليس فقط ذلك بل يمكن معرفه كل ما يحتوى المحمول على معلومات وقد حدث ذلك فى المانياالا ان احد كبار مستشارى الانظمه المعلوماتيه اراد اثبات عكس ذلك الا انه عندما قام بمسح الكترونى بمساعده الحاسوب مع استخدام هوائى تمكن من اظهار جميع ارقام الهواتف ومعرفه من اتصل بمن ومتى وكل المعلومات كل ذلك فى فتره قليله جدا وتلك المشكله ليست جديده فقد حذر كثير من العلماء منها من قبل ولكنى حقيقه لا اعرف حتى الان هل قاموا بوضع برامج للحمايه من سرقه المعلومات ام لا ولكن كل ما استطيع ان انصح به لا تترك البلوتوث مفتوحا ولا تستقبل اى شىء من شخص لا تعرفه والاجهزه التى تخلو من البلوتوث هى التى تكون اكثر امانا .

 

Internet Software Evolution -Part 4-

Communicate Using Internet Protocol

In the last series of articles, we got (Introduced To The History of Internet Evolution[1, 2, 3]). Actually, we have not yet reached the “Internet” as we know today. We have learned a lot in the last article “episode 3”, but there is still more to learn. If you are wondering what this series of articles is about, hopefully you will find out soon. Be Patient!

In the 1960s, twenty years after Vannevar Bush proposed MEMEX, the word hypertext was coind by Ted Nelson. Ted Nelson was one of the major visionaries of the coming hypertext revolution.     
He knew that the technology of his time could never handle the explosive growth of information that was proliferating across the planet. Nelson popularized the hypertext concept, but it was Douglas Engelbart who developed the first working hypertext system. At the end of World War II, Douglas Engelbert was a 20-year-old U.S Navy radar technician in the Philippines. One day, in a Red Cross library “those are places we rarely visit nowadays”, he picked up a copy of of the Atlantic Monthly dated July 1945. He happened to come across Vannevar Bush’s article about the MEMEX automated library system and was strongly influenced by this vision of the future of information technology. Sixteen years later, Engelbert published his own version of Bush’s vision in a paper presented for the Air Force Office of Scientific Research and Development. In Englebert’s paper, “Augmenting Human Intellect: A Conceptual Framework”, he described an advanced electronic information system:

“Most of the structuring forms I’ll show you stem from the simple capability of being able to establish arbitrary linkages between different substructures, and of directing the computer subsequently to display a set of linked substructures with any relative positioning we might designate among the different substructures. You can designate as many different kinds of links as you wish, so that you can specifiy different display or manipulative treatment for the different types”

[Source: Douglas Engelbert, “Augmenting Human Intellect: A Conceptual Framework”, in a report for the Air Force Office of Scientific Research and Development, October 1962] . 

Engelbertjoined Stanford Research Institute in 1962. His first project was Augment, and its purpose was to develop computer tools to augment the graphical user interface (GUI), and the first working hypertext system, named NLS (derived from on-line System). NLS was designed to cross reference research papers for sharing among geographically distributed researchers. NLS provided group-ware capabilities, screen sharing among remote users, and reference links for moving between sentences within a research paper and from one research paper to another. Engelbert’s NLS system was chosen as the second node on the ARPANET, giving him a role in the invention of the Internet as well as the World Wide Web.

In the 1980’s, a precursor to the web as we know it tday was developed in Europe by Tim Berners-Lee and Eobert Cailliau. Its popularity skyrocketed, in large part because Apple Computer delivered its HyperCard product free with every Macintosh bought at that time. In 1987, the effects of hypertext rippled through the industrial community. Hypercard was the first hypertext editing system available to the general public, and it cautht on very quickly. In the 1990s, Marc Andressen and a team at the National Center for Supercomputer Applications (NCSA), a research institute at the University of Illinois, developed the Mosaic and Netscape browsers. A technology revolution few saw coming was in its infancy at this point in time.

While March Andressen and the (NCSA) team were working on their browsers, Robert Cailliau at CERN independently proposed a project to develop a hypertext system. He joined forces with Berners-Lee to get the web initative into high gear. Cailliau rewrote his original proposal and lobbied CERN management for funding for programmers. He and Berners-Lee worked on papers and presentations in collaboration, and Cailliau helped run the very first WWW conference.

In the fall of 1990, Berners-Lee developed the first web browser (First web browser, created by Tim Berners-Lee, figure can be found at www.tranquileye.com/cyber/index.html) featuring an integrated editor that could cretae hypertext documents. He installed the application on his and Cailliau’s computers, and they both began communicating via the first web server, at info.cern.ch, on December 25, 1990.

a few months later, in August 1991, Berners-Lee posted a notice on a newsgroup called alt.hypertext that provided information about where one could download the web server and browser. Once this information hit the newsgroup, new web servers began appearing all over the world almost immediately. Following this initial success, Berners-Lee enhanced the server and browser by adding support for the FTP protocol. This made a wide range of existing FTP directories and Usenet newsgroups instantly accessible via a web page displayed in his browser. He also added a Telnet server on info.cern.ch, making a simple line browser available to anyone with a Telnet client.

The first public demonstration of Berners-Lee’s web server was at a conference called Hypertext 91. This web server came to be known as CERN httpd (short for hypertext transfer protocol daemon), and work in it continued until July 1996. Before work stopped on the CERN httpd, Berners-Lee managed to get CERN to provide a certification on April 30, 1993, that the web technology and program code was in the public domain so that anyone could use and improve it. This was an important decision that helped the web to grow to enormous proportions.

In 1992, Joseph Hardin and Dave Thompson were working at the NCSA. When Hardin and Thompson heard about Berners-Lee’s work, they downloaded the Viola WWW browser and demonstrated it to NCSA’s Software Design Group by connecting to the web server at CERN over the Internet. The Software Design Group was impressed by what they saw. Two students from the group, Marc Andreessen and Eric Bina, began work on a browser version for X-Windows on Unix computers, first released as version 0.5 on January 23, 1993 (The original NCSA Mosaic browser, image can be found at http://www.nsf.gov/od/lpa/news/03/images/mosaic.6beta.jpg). Within a week, Andreesson’s release messge was forwarded to various newsgroups by Berners-Lee. This generated a huge swell in the user base and subsequent redistribution ensued, creating a wider awareness of the product. Working together to support the product, Bina provided expert coding support while Andreessen provided excellent customer support. They mentioned the newsgroups continously to ensure that they knew about and could fix any bugs reported and make the desired enhancements pointed out by the user base.

Mosaic was the first widely popular web browser available to the general public. It helped spread use and knowledge of the web across the world. Mosaic provided support for graphics, sound, and video clips. An early version of Mosaic introduced forms support, enabling many powerful new uses and applications. Innovations including the use of bookmarks and history files were added. Mosaic became even more popular, helping further the growth of the World Wide Web. In mid-1994, after Andreesseen had graduated from the University of Illinois, Silicon Graphics founder Jim Clark collaborated with Andreessen to found Mosaic Communications, which was later renamed Netscape Communications.

In October 1994, Netscape released the first beta version of its browser, Mozilla 0.96b, over the Internet. The final version, named Mozilla 1.0, was released in December 1994. It became the very first commercial web browser. The Mosaic programming team then developed another web browser, which they named Netscape Navigator. Netscape Navigator was later renamed Netscape Communicator, then renamed back to just Netscape (The original Netscape browser image can be found at http://browser.netscape.com/downloads/archive).

During this period, Microsoft was not asleep at the wheel. Bill Gates realized that the WWW was the future and focused vast resources to begin developing a product to compete with Netscape. In 1995, Microsoft hosted an Internet Strategy Day and announced its commitment to adding Internet capabilities to all its products. In fulfillment of that announcement, Microsoft Internet Explorer arrived as both a graphical Web browser and the name for a set of technologies.

In July 1995, Microsoft released the Windows 95 operating system, which included built-in support for dial-up networking and TCP/IP, two key technologies for connecting a PC to the Internet. It also included an add-on to the operating system called Internet Explorer 1.0. When Windows 95 with Internet Explorer debuted, the (WWW) became accessible to a great many more people. Internet Explorer technology originally shipped as the Internet Jump start Kit in Microsoft Plus! For Windows 95.

One of the key factors in the success of Internet Explorer was that it eliminated the need for cumbersome manual installation that was required by many of the existing shareware browsers. Users embraced the “do-it-for-me” installation model provided by Microsoft, and browser loyalty went out the window. The Netscape browser led in user and market share until lead in 1999. This was due mainly to its distribution advantage, because it was included in every version of Microsoft Windows. The browser wars had begun, and the battlefield was the Internet. In response to Microsoft’s move, Netscape decided in 2002 to release a free, open source software version of Netscape named Mozilla (which was the internal name for the old Netscape browser. Mozilla has steadily gained market share, particularly on non-Windows platforms such as Linux, largely because of its open source foundation. Mozilla Firefox, released in 2004, became very popular almost immediately.

Story Begins .. 😉

~Haitham El-Ghareeb

 

Internet Software Evolution -Part 3-

Establishing a Common Protocol for the Internet : 

Since the lower layers were provided by the IMP host interface, the NCP essentially provided a transport layer consisting of the ARPANET Host-to-Host Protocol (AHHP) and the Initial Connection Protocol (ICP). AHHP specified how to transmit a unidirectional, flow-controlled data stream between two hosts. ICP specified how to establish a bidirectional pair of data streams between a pair of connected host processes. Application protocols such as File Transfer Protocol (FTP), used for file transfers, and Simple Mail Transfer Protocol (SMTP), used for sending email, accessed network services through an interface to the top layer of the NCP.

On January 1, 1983, knows as Flag Day, NCP was rendered obsolete when the ARPANET changed its core networking protocols from NCP to the more flexible and powerful TCP/IP protocol suite, marking the start of the Internet as we know it today.

I will skip the rest of the story. In this series of articles, we have gone through the evolution of TCP/IP.
You can consider those articles under Computer Networks category. Later, you will find out how small this world is.

Lessons learned from this series:

• Never Underestimate your field of Study: Vannever Bush contributed majorly in inventing the Internet,
while he was manly a librarian.
• Innovation is Important: even in simple tasks, you shall always be thinking about innovative ways for achieving tasks.
Vannever Bush was thinking about innovative ways to present encyclopedias.
• Keep working: Vannever Bush kept formalizing his imagination of MEMEX between 1936 and 1945. How long is that?
• Collaboration: Librarian, Electronic and Electrical Engineer, Researcher invented the Internet. No one could have invented Internet solely.
• Transform Knowledge: Licklider brought Lawrence Roberts, believing he is the person to implement the vision.
If you found someone that does things better, don’t hesitate to collaborate with him to get your ideas implemented. History remembers you both.
• Same idea fits in different places: Paul Baran implemented the same idea “Packet Switching” at RAND Corporation, and DARPA net.
• Listen Carefully: After the meeting, Roberts stayed behind and listened as Clark
elaborated on his concept to deploy a minicomputer.
• Stand on the Giants’ Shoulders: Avoid reinventing the wheel. People are working
on projects, search for them, build your project over their projects, so you will reach
further places. AHHP and ICP were built over NCP, TCP/IP was built over NCP.
• Think Globally, Act Locally: Seeing the full picture is important, but you need to take
small repetitive, well studied steps to reach your goal. Internet was built step by step
over years.
• Obsoleting your work: It is required to keep updating your work, keep upgrading it, and
knowing the right moment to mark certain work as obsolete, and present new work.
• Keep Working! 😉

References
1. http://en.wikipedia.ort/wiki/Vennevar_Bush
2. http://www.livinginternet.com/i/ii_summary.htm
3. http://www.theatlantic.com/doc/194507/bush
4. http://en.wikipedia.org/wiki/Norbert_Wiener
5. http://www.computermuseum.li/Testpage/IBM-SAGE-computer.htm
6. http://www.urbandictionary.com/define.php?term=Bass+Ackwards

“ defined this as “The art and science of hurting blindly in the wrong direction with no sense of the impending doom about to be inflicted on one’s sorry ass. Usually applied to procedures, processes, or theories based on faulty logic, or faulty personnel. “

 

Internet Software Evolution -Part 2-

In 1957, the Soviet Union launched the first satellite, Sputnik I, promoting U.S. President
Dwight Eisenhower to created the Advanced Research Projects Agency (ARPA) to regain the technological lead in the arms race. ARPA (renamed DARPA, the the Defense Advanced Research Project Agency, in 1972) appointed J. C. Licklider to head the new Information Processing Techniques Ofice (IPTO).

Licklider was given a mandate to further the research of SAGE system. SAGE system was a continental air-defense network commissioned by the U.S> military and designed to help protect the United States against a space based nuclear attack. SAGE stood for Semi-Automatic Ground Environment [5]. SAGE was the most ambitious computer project ever undertaken at the time, and it required over 800 programmers and the technical resources of some of the America’s largest coporations. SAGE was started in the 1950s and became operational by 1963. It remained in continous operation for over 20 years, until 1983.

While working at ITPO, Licklider evangelized the potential benefits of a country-wide  communications network. His chief contribution to the development of the Internet was his ideas, not specific inventions. He foresaw the need for networked computers with easy user interfaces. His ideas foretold of graphical computing, point-and-click interfaces, digital libraries, e-commerce, online banking, and software that would exist on a network and migrate to wherever it was needed. Licklider worked for several years at ARPA, where he set the stage for the creation of the ARPANET. He also worked at Bolt Beranek and Newman (BBN), the company that supplied the first computers connected on the ARPANET.

 

After he had left ARPA, Licklider succeeded in convincing his replacement to hire a man named Lawrence Roberts, believing the Roberts was just the person to implement Licklider’s vision of the future network computing environment. Roberts led the development of the network. His efforts were based on a novel idea of “Packet Switching” that had been developed by Paul Baran while working at RAND Corporation.
The idea for a common interface to the ARPANET was first suggested in Ann Arbor, Michigan, by Wesley Clark at an ARPANET design session set up by Lawrence Roberts in April 1967. Robert’s implementation plan called for each site that was to connect its computer to the network. To the attendees, this approach seemed like a lot of work. There were so many different kinds of computers and operating systems in use
throut the DARPA community that every piece of code would have to be individually written, tested, implemented, and maintained. Clark told Roberts that he thought the design was “bass-ackwards.” [6]

After the meeting, Roberts stayed behined and listened as Clark elaborated on his concept to deploy a minicomputer called an Interface Message Processor (IMP) at each site. The IMP would handle the interface to the ARPANET network. The physical layer, the data link layer, and the network layer protocols used internally on the ARPANET were implemented on this IMP. Using this approach, each site would only have to write one interface to the commonly deployed IMP. The host at each site connected itself to the IMP using another type of interface that had different physical, data link, and network layer specification. These were specified by the Host/IMP Protocol in BBN Report 1822.

So, as it turned out, the first networking protocol that was used on the ARPANET was the Network Control Program (NCP). NCP provided the middle layers of a protocol stack running on an ARPANET-connected host computer. The NCP managed the connections and flow control among the various processes running on different ARPANET host computers. An application layer, built on top of the NCP, provided services such as email and file transfer. These applications used the NCP to handle
connections to other host computers.