Networking Topology

Think of a topology as a network's virtual shape or structure. This shape does not necessarily correspond to the actual physical layout of the devices on the network. For example, the computers on a home LAN may be arranged in a circle in a family room, but it would be highly unlikely to find a ring topology there.

Network topologies are categorized into the following basic types:

• bus
• ring
• star
• tree
• mesh

More complex networks can be built as hybrids of two or more of the above basic topologies.

Bus Topology

Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.

Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.

Ring Topology

In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.

To implement a ring network, one typically uses FDDI,SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.

Star Topology

Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch, and router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.

Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)

Tree Topology

Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.

Mesh Topology

Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.

A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.

Summary

Topologies remain an important part of network design theory. You can probably build a home or small business computer network without understanding the difference between a bus design and a star design, but becoming familiar with the standard topologies gives you a better understanding of important networking concepts like hubs, broadcasts, and routes.

source : compnetworking.about.com

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How To Maximize Or Increase The Speed Of Your Wi-Fi Connection

Today, enterprises are deploying wireless LANs for corporate applications and home users that involve e-mail, Web browsing, and access to various server-based databases. The need for higher data rates and techniques to improve performance of wireless LANs is becoming crucial to support these types of applications. To get that extra performance, you may have a lot to consider.

Select The Right Physical Layer

An important element that impacts the performance of a wireless LAN is the selection of the appropriate Physical (PHY) Layer (i.e., 802.11a, 802.11b, or802.11g). 802.11a offers the highest capacity at 54Mbps for each of twelve (maximum) non-overlapping channels and freedom from most potential RF interference. 802.11b provides 11Mbps data rates, with only three non-overlapping channels. 802.11g will eventually extend 802.11b networks to have 54Mbps operation, but the three non-overlapping channels limitation will still exist. Of course requirements dictate needs for performance, which will point you toward a particular PHY. If you need maximum performance, then 802.11a is the way to go, but you may need more access points because of the weaker range it has compared to 802.11b.

MIMO ANTENNA

If you are using 802.11g – consider getting an MIMO antenna (which allows faster speeds at greater distances.)

Replace Other 2.4 GHz Devices

You may need to replace your 2.4GHz cordless phones with either a 900Mhz or 5.8GHz style cordless phone due to interference. These phones and other nearby wireless LANs can offer significant interfering signals that degrade the operation of an 802.11b wireless LAN. These external sources of RF energy in the 2.4GHz band periodically block users and access points from accessing the shared air medium. As a result, the performance of your wireless LAN will suffer when RF interference is present. So obviously you should strive to minimize sources of RF interference and possibly set the access point channels to avoid the interfering signals.

Properly Set Access Point Channels

The 802.11b standard defines 14 channels (11 in the U.S.) that overlap considerably, leaving only three channels that don’t overlap with each other. For access points that are within range of each other, set them to different channels (e.g., 1, 6, and 11) in order to avoid inter-access point interference. You can also take advantage of the automatic channel selection features that some access points offer. With 802.11a, this is not an issue because the 802.11a standard defines separate, non-overlapping channels.

Maximize RF Coverage

If access points are too far apart, then some users will be associating with the wireless LAN at something less than the maximum data rate. For example, users close to an 802.11b access point may be operating at 11Mbps; whereas, a user at a greater distance may only have 2Mbps capability. In order to maximize performance, ensure that RF coverage is adequate and spread out nearby for optimum performance.

Same Router And Network Adapter

Choose your router and network adapters from the same company. Manufacturers usually have a proprietary “turbo” mode that only works when using both their router and network adapters. As a side benefit; your overall configuration is usually easier.

Upgrade Your 802.11b

Upgrade your 802.11a and 802.11b devices to 802.11g, which is much faster, and is backward-compatible with 802.11b devices, although a small one room environment (i.e. apartment, dorm room) with no future expansion should use 802.11a.

Wired Connection

Whenever possible, connect computers using a wired connection! Yes, this is an “Anti-tip” because you’re not even using the wireless network – but a direct connection is dramatically faster and more secure!

Wireless Router On Central Location

If possible, place your wireless router (or access point) in a central location. Obviously, the closer you are to the access point; the better. But do not necessarily place the device on your roof (or up too high) – 4 to 6 feet off the ground is perfect.

Update Your Windows Wireless Network Driver

Update your Windows Wireless Network Driver. While Microsoft Update, is “supposed” to notify you of updates to your drivers – it’s best to visit the manufacturers website to double-check. Updates usually only add a new feature, or increase stability and security; but sometimes can improve performance.

Update And Upgrade Your Router

Update your Router’s firmware. Most routers easily update their firmware directly from their software. Updates add new features, increase stability and security; and also sometimes help in improving the performance. The antenna that comes with your device is usually a low powered and omni-directional. Upgrade to a more powerful (powered) antenna. If your router is near an outside wall, get a high-gain antenna that focuses the wireless signals only one direction.

resource : www.addictivetips.com

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WIRELESS HACK

Ever wondered just how secure your WEP protected wireless network is? Well today I'll show you how to test it. There have been a lot of articles written about this subject already and by now it is common knowledge that WEP is only the barest of security precautions. I'm going to show you how you can test your own wireless network's security using the linux livecd distro back|track. Before we go any further, I feel it necessary to mention two things. The first being the ethics of hacking. Most of you are probably familiar with this subject already but, just to refresh your memory. Second, it goes without saying that this is for YOUR OWN NETWORK TESTING PURPOSES ONLY. Unauthorized access of other people's networks is illegal. If you have problems or questions about anything in this guide, for the love of god use google/wikipedia and look it up first. Don't just start ranting on forums like a moron without doing a little research first. There are probably other people who have had the same problems and solved them already. Ok, parental rant over. Lets get down to the dirty stuff:

First of all, you'll need to check and make sure your wireless card has the right chipset. Most wireless cards are programmed only to accept data that is addressed to them. Other cards, specifically the ones that are of use for wifi sniffing, are capable of picking up all traffic that is flying through the air. Common types are Atheros, Prism, Aironet, Realtek, Hermes, etc based cards. You are on your own figuring out what type of chipset your wireless card has, as its too vast to get into here, but check this thread for more info. Your probably just going to have to search for your specific card to find out what chipset it has then compare it to this compatability list. For a good discussion on types of cards that work, check this http://forums.remote-exploit.org/showthread.php?t=2191

Next, download a copy of back|track, a slackware distro designed for security testing purposes. This is a linux livecd, which means it will boot the entire OS from the cd. Download the ISO and use a burning program such as Nero, Alcohol or my personal favorite, the awesome freeware cd/dvd burning program cdburnerXP to burn the disk image to a cd. Pop the disk in and reboot, and boot from the disk. Back|track may take a while to boot up.

When back|track boots up (and hopefully finds all your hardware) you will be presented with a login screen. To quote the venerable xatar, "Read the f**king screen!" The login, as it says above the prompt is "root" and the password is "toor" (minus the ""). Note that linux is case sensitive. After you are logged in, you could run all of the commands I will get into later from this prompt. But thats no fun, so type in:

xconf



This should create a file /etc/X11/xorg.conf and autodetect your video settings. (with nvidia cards, you may still have video problems as I did, such as not getting above 640x480... should you choose to install backtrack to the harddrive, check out http://forums.remote-exploit.org/showthread.php?t=2176&highlight=nvidia for more info on fixing this)

To get the KDE gui desktop to start up, simply type:

startx



If everything goes smoothly, you should be awash in the beautiful glow of the back|track KDE desktop. Given the beautiful read only nature of the livecd, you can do anything to this operating system and not have to worry about messing it up. If things get a little weird, or screwed up, just reboot and the OS is back to normal. So GO EXPLORE, run random programs, see what they do, go nuts.

At the bottom left of the screen is a little icon that looks like a monitor with a black screen. This is called the bash prompt. This is where you will be spending most of your time, so click on this to open up a new bash prompt. Note that you can double click on the bar to the right of the tab that says "Shell" and it will create a new bash tab, negating the necessity to open up multiple instances of the bash window. First, a few networking commands to get you up to speed on your own system. Type

ifconfig -a

ifconfig

This will show you a list of all compatible network cards on your system. You should see a list of devices such as ath0, eth0, wifi0, wlan0 etc. One of these is your wireless card. If you have an Atheros based card, it will be ath0. Make note of the name of your card, as you will be using it later. For the rest of this guide, I will be using ath0 since that is the card I have. Replace ath0 with whatever card you have.

You can also check out your wireless cards specifically by typing in:

iwconfig

I've got two wireless cards. The one built into my laptop, an intel card (eth0) and an Atheros pcmcia card (ath0). Now that we have the name of our wireless cards, we can start sniffing. Some like to use Kismet to sniff for networks, but I find using airodump-ng to be easier and ultimately more effective. In your bash prompt, type:

airodump-ng --write out --ivs --abg ath0



This starts airodump-ng and tells it to begin sniffing data, write it to the file out, only capture IVs (Initialization Vectors), search the a, b and g bands using the ath0 card. Keep in mind, every time you specify the same output file name, such as "out", airodump-ng will append the file name with "-##" such as out-01.ivs, out-02.ivs, etc.You will see a list of access points on the top half of the screen, and clients on the bottom. Find your access point in the list. Write down the BSSID or Mac address of the access point and any connected clients. You'll need it later. From now on in this document, the access point's mac address will be referred to as APmac and the client mac as CLmac. The goal of the attack is to capture as many unique IVS as possible. Every time data is sent between the wireless server and client, each packet contains IV which are collected and then run through the aircrack-ng program for computation.

You should be seeing a ton of numbers flying by, but not updating vary quickly. Thats because airodump-ng is searching all channels. Once you see your network, note what channel it is on (under the CH header). Stop airodump-ng by hitting:

ctrl-c



Now start it up again but this time we will add --channel # where # is the channel number of the access point, say, channel 6

airodump-ng --channel 6 --write out --ivs --abg ath0

airodump

Airodump-ng should be running much faster now, and updating constantly. You will see a number rising very quickly, this is generally the beacons. Beacons just basically say "hey, i'm an access point" about 10 times a second. You can judge the quality of your connection by how fluid the rise in beacons are. Other than this, they are useless for our purposes. For this type of attack it is important for there to be a client connected to the access point. So march over to your other computer and log on to the net wirelessly. In backtrack, you should see at the bottom a client pop up, the first MAC is the access point and the 2nd is the Client. Write down both. Open a new bash prompt and type:

aireplay-ng -2 -b APmac -d ff:ff:ff:ff:ff:ff -m 68 -n 68 -p 0841 -h CLmac ath0

aireplay

Where APmac is the mac address (bssid) of the access point and CLmac is the mac address of the client. For a detailed explanation of what all these settings do, open up a new bash prompt and just type aireplay-ng and it will spew out all the controls and what they do. The only one not explained is that the very first -2 tells aireplay to do the 3rd attack method in the list at the bottom (the first being 0).

aireplay-ng will now start sniffing for a certain type of packet with a length no more and no less than 68 bytes between client and access point. It will say "Read ### packets". At this point, if there is significant data transfer between the client and ap, it may snag the right type of packet already and there is no need to do the next step. In this case, hit Y to use the packet and skip the next step. If however, it keeps reading packets for a while (more than a couple min) and does not pop up saying "Use this packet?" then do the following:

Open a new bash prompt and type:

aireplay-ng -0 1 -a APmac -c CLmac ath0

This command will effectively terminate the connection between the AP and the client forcing the client to re-connect. It is this re-connection packet that we are looking to scoop up with the first instance of aireplay.

Go back to the first instance of aireplay and you should see something at the bottom of the screen saying "Use this packet?" Hit Y and aireplay will start sending out tons of packets to the AP. Switch over to airodump-ng which should still be running in the first bash prompt. Look at the data rate of the targeted AP. If all is going well, Aireplay is spewing out packets like mad to the access point and airodump-ng is picking up the chatter in between, the data should be rising quickly. This is exactly what we want.

If for some reason the data isn't going up quickly, go back to the first aireplay-ng and hit:

ctrl-c



If aireplay had picked up any more packets, it will prompt you again if you want to use them. Try more packets. Also, you may need to get closer to your access point or try the aireplay-ng -0 method again. Experiment. Once you've got the data rate going up quickly, start aircrack-ng and start crunching the numbers. Type in

dir



To get a list of the files. One file should be the out file that you specified in airodump-ng, specifically out-01.ivs. Each time airodump-ng is started with the same file output name, it creates a new one tacking on -01, -02, etc. Make sure you know which one you are outputting to.

Type in:

aircrack-ng -f 2 -a 1 -b APmac -n 64 out-01.ivs





Again, if you want to know what all the parameters mean, open up a new bash and type aircrack-ng and it will tell you. Basically -f is the fudge factor- default is 2, a higher number will be a more thorough but slower search. -b filters out all but the specified mac of the AP, -n says to search for a 64 bit key. If it runs for a long time and finds nothing, either you don't have enough IVs, or you are searching under the wrong key length. Try 128. You can also run multiple instances of of aircrack with different variables. Aircrack will continually update, notice the increasing IVs in the upper right as long is airodump-ng and aireplay are still going strong. After a bit of time, it should spit out your WEP key. Congrats! You now know how hard it is breaking into YOUR OWN NETWORK. Perhaps switch to WPA? If it didn't work, there could be any number reasons why. Do a little searching on the backtrack forums, google, etc, try setting up a different access point or learn how to do another type of attack, learn how to configure your hardware properly, etc, etc, etc. Take your time and explore the OS, if your new to linux, like i was when i started using backtrack, you'll have a lot to learn.



As a side note, In order to connect to a wireless network in backtrack, you must type in

iwconfig ath0 essid nameofnetwork key whateverthekeyis

ifconfig ath0 up

dhcpcd ath0

A message should pop up in the bottom right of the screen saying something about ath0 being connected. To disconnect, before switching to another network, type:

ifconfig ath0 down

then repeat the steps above with the new network information.

Further reading: http://www.cs.wright.edu/~pmateti/InternetSecurity/Lectures/WirelessHacks/Mateti-WirelessHacks.htm

I'd like to thank muts, max, redkommie, jacky, digi, creaters of backtrack, xatar for writing a lot of the guides that got me up to speed, the creators of aircrack-ng and all the awesome people on the rexploit forums.

resource: www.i-hacked.com

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MAKE WAJAN BOLIC ANTENNA

Introduce
Basicly the function of this wok is being wave reflector like parabola. More bigger of the wok more strong the wave we can get. This antenna can connect on the rang 1-1,5 km.

Make USB WIFI ANTENA USB (Wajanbolic)
ENGLISH VERSION

Material
1. Big diameter of wok(more bigger more better)
2. PVC pipe with diameter 3 inch.
3. Doff 3″ (to close the top of PVC paralon) 2 piece
4. Aluminium foil
5. bolt wit size 12 or 14
6. Wifi USB Adapter
7. Double tape
8. UTP cable 10 meter
9. Pole (to make antenna more high)

Equipment
1. Ruler
2. Cutter

Procedure
1. Make the hole on the wok
2. Make USB ekstension with UTP cable
Calculate the focus of the wok D:diameter d:depth of the woke
F = D^2/(16*d) = 70^2 / (16*20)

example:

Parabolic dish with D = 70 cm, d = 20 cm
Distance focus from center dish : F = D^2/(16*d) = 70^2 / (16*20) = 15.3 cm

Cut the PVC pipe 30 cm, then give a mark for the distance of the feeder (free aluminium foil area).


1. Make the hole on pipe and don’t forget on the mark of focus to take Usb Wifi adapther
2. Then wrap pipe with aluminium foil except the feeder, if the alumunium foil doesn’t have a glue, use double tape.
3. Take the doff to close the pipe.
4. Then take first doff on hole of the wok. Then use the bolt and rool it.
5. Take the pipe on the doff.
6. Make 10 meter usb ekstension with UTP cable. Cut the short ekstension then open the cable. Choose the color of UTP and pair with the short USB ekstension. Nop roblem if u choose diferent color but you have to do again for the other point. With the same color of pair.example usb red>utp brown, usb blueutp green.
7. Connect the Usb ekstention with usb wifi. Take the antenna on the top of pole. Connect the ekstention cable to the computer and scan the wireless network.
8. When it’s connect you are ready to browsing, surfing, and wardriving.
pic. Tutuppancibolic (close with usb wajanbolic)

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MAKE WAJAN BOLIC ANTENNA

PENDAHULUAN
Pada umumnya peranan wajan (parabolic) adalah sebagai reflector, atau pemantul gelombang. Yang kemudian gelombang tersebut dipantulkan dari semua sisi wajan dalam satu titik yang dinamakan focus dengan tujuan sinyal semakin kuat. Dapat kita ambil dalam reflector lampu senter, sinar yang berada pada titik focus lebih terang daripada titik yang lainnya, begitu pula pada fungsi wajan bolic ini. Kesimpulannya Semakin besar wajannya semakin butuh banyak minyak gorengnya(hex2..)

BAHAN

1. Wajan diameter 36″ (semakin besar diametr semakin bagus)
2. PVC paralon tipis diameter 3″ 1 meter
3. Doff 3″ (tutup PVC paralon) 2 buah
4. Aluminium foil
5. Baut + mur ukuran 12 atau 14
6. Wifi USB Adapter
7. Double tape + lakban
8. Kabel utp 10meter
9. Tiang besi atau apabila budget mpet ya tiang bamboo(untuk meninggikan antenna, lebih tinggi dari bangunan)

PERALATAN

1. Penggaris
2. Pisau/ Cutter
3. Gergaji besi

PERKIRAAN HARGA

Wajan tempat penggorengan kira-kira sekitar Rp.45.000, Terus yang penting USB wirelesnya Rp.250.000 peralon 3 inc 1meter Rp.20.000, Kabel Utp (sebagai ekstensi usb) 10meter Rp.25.000. Bahan-bahan yang lain tidak dihitung dikarenakan harga murah dan mudah didapat.

TAHAP PENGERJAAN

1. Siapkan semua bahan dan peralatan yang dibutuhkan.
2. Lubangi wajan tepat di tengah wajan tersebut seukuran baut 12 atau 14, cukup satu lubang saja.

Kemudia, ukur diametr wajan, kedalaman wajan dan feeder/ titik focus. Untuk lebih jelas nya silahkan liat gambar di bawah.

Parabolic dish dg D = 70 cm, d = 20 cm

maka jarak titik focus dari center dish : F = D^2/(16*d) = 70^2 / (16*20) = 15.3 cm(ket :^àpangkat, *àkali, /àbagi)

Pada titik focus tsb dipasang ujung feeder. Untuk mendapatkan gain maksimum.

1. Potong PVC paralon sepanjang 30 cm, kemudian beri tanda untuk jarak feeder nya (daerah bebas aluminium foil). Untuk menentukan panjang feeder nya gunakan rumus di atas.
2. Beri lubang pada focus bagian paralon untuk meletakkan Usb Wifi
3. Selanjut nya, bungkus PVC paralon dengan dgn aluminium foil pada daerah selain feeder, klo aluminium foil yang ada tanpa perekat, maka untuk merekatkan nya bisa menggunakan double tape
4. Dan pasangkan doff tersebut ke PVC paralon
5. Kemudian, wajan yang telah di lubangi tadi dipasangkan dengan doff yang satu nya lagi, sebelum nya doff tersebut dilubangi sesuai dengan ukuran bautyang sudah di siapkan, dan kencangkan secukup nya.
6. Kemudian tinggal pasangkan PVC paralon tadi ke wajan yang sudah di pasang doff.
7. Buat Usb Ekstensi perpanjangan 10 m dengan UTP kabel caranya: Potong kabel perpanjangan menjadi 2, satukanlah masing-masing kabel perpanjangan dengan kabel UTP (pilih empat kabel saja) lakukan di ujung yang lain (jangan sampai menyatu) dengan catatan warna kabel dengan pasangan harus sama dengan ujung lainnya. Agar tidak terjadi kesalahan catat. Missal, usb biruàutp hijau, usb kuningà utp coklat. Lakban sambungan kabel tersebut.
8. Sambungkan USB dengan perpanjangan USB yang dibuat tadi. Pasangkan di tiang peninggi. Tancapkan kabel USB kekomputer dan scan wireless network.
9. Wajan bolic sudah siap untuk digunakan browsing, atau paling tidak untuk wardriving.

Gb. Tutuppancibolic (hampir sama dengan wajanbolic)

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