Emergency Communications in the Zombie Apocalypse : WiFi Direct

I've been thinking about writing about Emergency Communications(EMCOMM) during the up and coming Zombie Apocalypse. It doesn't matter if you don’t believe in Zombie’s, because they might not be real but an apocalypse is possible. My writing on EMCOMM will be spread out since there are many avenues of technology that we can use for communication. For my first article I am going to focus on Wi-Fi direct communication between smartphones. The reason I decided to start off with this, is that there are over a billion smartphones out there in the wild world. This data was collected in November of 2012 so imagine there are many more now.  

We've all seen Wi-Fi direct connection on our phones, but do we even know what its for or how to use it. According to Wikipedia Wi-FI direct “is a Wi-Fi standard that enables devices to connect easily with each other without requiring a wireless access point and to communicate at typical Wi-Fi speeds”. So one phone can connect to another phone without a wireless router, and do normal things that are done over Wi-Fi. What we are after is communication, and with Wi-Fi direct two smartphones are able to communicate without the need of any other device.

I didn’t want this article to turn into a review of various smartphone applications, therefore I chose two applications. One application is for voice communication and one for data communication, I tested them out made sure that they work as intended and will present them here. The first one is Wi-Fi Direct Walkie Talkie, the application is simple: you start it (on both phones), search for devices(each phone finds the other) and that's it you are connected. To talk you either press the volume up button or a on-screen button.  

What about more discreet communication, for the moments that a text message would be better than audio. FireChat an application available both on Apple’s IOS and Google’s Android, this application does the same as the above mentioned one but instead of exchanging audio it exchanges text messages. Once again all of this is done directly from one phone to another without the need for wireless routers or access points.

There are many applications that are able to run using Wi-Fi direct protocol, these are just two of them. I hope that this article sort of peaked your appetite and made you want to search for more Wi-Fi enabled applications and even give them a try. For my next article I am going to be writing an article on MotoTalk and how it can be used for EMCOMM. If you do not know what MotoTalk is stay tuned for my next write up and you’ll have a bit of an understanding.

P.S.

I know my writing is not the greatest, I expect that there are various if not many grammar, spelling, syntax, and other types of mistakes. It’s not a post on the english language and its greatness, it’s a post on a Zombie Apocalypse scenario you can’t expect perfect english. If you want to make any type of comments go ahead, but keep warned I might ignore them all even the nice one.

THX

ICND1 100-101 Chapter 2

I was thinking maybe I went a bit overhead with the last post. So I am going to be trimming it down from now on. Chapter two starts off with looking at both typical Small Office Home Office Local Area Networks.  A SOHO LAN usually consists of a Modem with some sort of internet connection either DSL or CABLE.  The modem in a SOHO LAN will incorporate a switch and even a wireless access point into once simple device.   In an Enterprise LAN we use the same offerings but they are usually separated into various devices. A Modem is replaced with a Router that acts as the gateway between buildings,  Dedicated switches within buildings that connect everything together, and Dedicated access points throughout the building to provide wireless access to users.  One Major difference is that in a SOHO LAN one device can take care of it since there are very few users. In an enterprise network we need devices to take care of specific tasks because they are faster and easier to manage.

Ethernet and Physical Layer Standards.  There are many Physical layer standards, which Ethernet can travel through. A quick comparison is the different type of people that speak English, it doesn't matter what ethnicity, race, color if they all speak English they are able to understand each other at different ends of the communication medium. Same goes with Ethernet, instead of races, ethnicity, colors we have different types of wires, connectors, signaling methods, the good thing is that Ethernet runs through these physical standards therefore it is able to talk across different physical places.

T is for Copper and X is for Fiber. 10BaseT (10Mbps) 100BaseT(100Mbps)1000BaseT(1000 Mbps) 10GBasteT(10 Gbps).

100 Meters

1000Base-LX (1000 Mbps) 5000 Meters Fibre

UTP Unshielded Twisted Pair.

10 Base T , 100Base T

Pair 1 (1,2)

Pair 2 (3,6)

Straight trough

Crossover crosses Pairs 1->2

1000 Base T

Pair 1 (1,2)

Pair 2 (3,6)

Pair 3 (4,5)

Pair 4 (7,8)

Straight trough

Crossover crosses Pairs

1->2

3->4

No matter what medium is used an Ethernet header will tell the receiving end what to do with the packet.

Routers, PC’s, and WAP Transmit on Pins 1,2

Hubs and Switches Transmit on Pin 3,6

If you are connecting similar devices you need a Crossover cable.

A Data Link PDU or Ethernet Frame

Header[[[[[[7Byte Preamble, 1 Byte SFD, 6 Byte Destination, 6 Byte Source ,2 Byte Type,]]]]]] Data and Pad (46-1500) TRAILER [[[[[4 Byte FCS]]]]]]]

MAC Addresses 3 Byte Organization 3 Byte Device

The Computer does a Math Calculation to the frame and adds it to FCS.

Full Duplex, Half Duplex… Older hardware like hubs needs Half Duplex because of CSMA/CD. Carrier Sense Multiple Access Collision Detection.  There is a potential for collisions when using these devices and that is because some devices might transmit at the same time. With a switch that is avoided.

Hubs send stuff out on all ports, like a repeater except the one it came in on.

Switches send it out only on the correct port.

This was a bit more than notes , but this is merely what I want them to be.

ICND1 100-101 Chapter 1

Chapter 1

The chapter starts with the broader picture of networking; it compares a computer network to the network that the United States Postal Service has to send out our mail. The sender does not need to know how the letter arrives at the other end, just as the user of a computer does not need to know how data is transferred across the network.  It compares our local post office to Routers in the networking world. If the letter does not belong to that post office it forwards it to next post office depending on the rules set until it gets to the local post office that takes care of the receivers address.

Just like each of our homes have unique physical addresses; computers on a network must also have a unique address in order for the information to be able to arrive correctly. The most important address in the Internet world is our IP address this corresponds to our unique internet connection.

We’ve seen TCP/IP all over the place, but it wasn’t like this when networking started. It was a mess of sorts with different vendors having different protocols. 1980’s was IBM, DEC as well as various other smaller vendors. In the 90’s TCP/IP came in to play and by the 2000’s it took over the networking world.  OSI which stands for Open Systems Interconnect was a direct competitor to TCP/IP but because of its slowness was beaten by TCP/IP. Everyone though that OSI would win the battle since it was a lot more detailed, because of this OSI is still widely used for Documentation and Explanation purposes.  Both TCP/IP and OSI are models that we can divide into sections.

There are two ways to look at the TCP/IP model, the older way and the newer way. I will only be focusing on the newer way which divides the model into Five Sections.    

1. Application 2. Transport 3.Network 4. Data Link 5. Physical

The Application layer deals, with you guessed it applications. Web Browsers, Email Clients, Phones.  It uses protocols such as HTTP for browsers, SMTP and POP for Email clients, SIP and VOIP for Phones, and alike.  The transport layer Provides services to the application layer, one of the most important service that was mentioned in chapter one is Error recovery.  Protocols that are used at the transport layer are TCP and UDP.  Network, provides services to Transport and it does so by using the IP protocol specifically its Addressing and Routing mechanisms.  Data Link was a bit more obscure for me, but it basically defines the protocols that are used to send the date over the physical medium, in the case of most every network it is the Ethernet protocol but it also includes Point-to-Point and T1 and I would assume frame relay.  Physical is exactly that, the physical medium that the DATA will flow through. 

The Information or packets that flow through the different levels of the TCP/IP model have different names. The reason that they have different names is because each layer of the model encapsulates the data with headers and some of them add trailers. The easiest way I remember it is SPF as it if was sunscreen. Segment, Packet, Frame and they only correspond to the middle layers. Transport is segment, Network is Packet, and Frame is Data Link.  The only layer to add a trailer so far is the Data Link Layer.  Same Layer and Adjacent layer interaction is mentioned, Same Layers can interact when dealing with different computer communication, and adjacent layer interaction is used when the top layer asks the bottom layer for help with something.

What about the OSI model, that one is a bit more complex this is why it’s awesome. It has seven layers, they are (please, do, not, throw, sausage, pizza, away) Physical, Data Link, Network, Transport, Session, Presentation, Application, and that is in reverse order.  You can see the bottom four layers of the OSI model correspond to the bottom four of the TCP/IP model.  You can see that we added Presentation and Session.

The application layer still provides an interface to application; in this case it also defines the process for user authentication. Same Protocols as before are used HTTP, FTP, POP, and VoIP.

Presentation Layer defines how things look J not only does it define it also negotiates how they look. JPG, ASCII, binary. Encryption is also under this layer.

Session, here is another weird one for me. The session layer knows how to start control and end the communications between devices.  IT controls multiple bidirectional messages, and is able to have a seamless view.

Transport layer delivers data to another system using protocols like TCP and UDP.  It has error recovery and flow control.  

Network layer also uses the Internet Protocol (IP). This includes Logical Addressing, Routing, and path Determination.

Data Link Layer in the OSI model defines when a device can send and when to wait. DL layer defines what headers and trailers must conform to.  Ethernet, HDLC

Physical, the same as the TCP/IP model and this includes the medium that the data will flow through UTP/STP, COAX, and Fiber.

Remember Segments, Packets and Frames. The OSI model has something similar. But they are easier to remember L7PDU, L6PDU……, L2PDU, PDU stands for Protocol Data Units.

In the Cisco World and probably other vendors different devices work at different levels of the OSI model. Hosts and Firewalls work both at the Application and Transport Levels (7,4), Routers are Level Three devices because they look at IP addresses, Switches, WAP, Cable Modems and DSL Modems work at Layer Two, Layer one includes Repeaters, Hubs and cabling.

I understand my writing is not great but I don’t think it’s horrid. If you have negative comments I’d love to hear them, send them to my editor /dev/null.  If you have actual comments go ahead and post them. I’m not sure If I will make a video for this first chapter, but If I do make one I’ll go ahead and let you know.

CCENT/CCNA Certification Journey

Back in high school, which was a while ago I took this Cisco Networking Academy with the intention of trying to pass the Cisco Certified Networking Associate (CCNA). Well long story short it was High School and even though I took the class I never attempted to take the CCNA. Fast forward I know realize I should have taken advantage of the situation. Isn’t life filled with thousands of those situations?  I’ve decided to study for the CCNA certification and actually attempt and pass it this time around.  I purchased the official certification guide from Cisco.  I’ll be starting with ICND1 100-101 which is a stepping stone towards the CCNA certification. By passing the ICND1 100-101 I will be a Cisco Certified Entry Networking Technician (CCENT).  

They say the best way to learn something is to teach it, and that is exactly what I intend to do.  How? I’ll be writing a summary of all of the chapters and post them here on my blog. Aside from that I plan to make some videos that correspond to each of the chapters.  Who is the audience, well no one really this is more for me, but if anyone actually stops by that would be awesome. Once I finish the book, I will be taking the CCENT certification and I will be posting updates and information about that when the time comes.  I will be posting the summary of chapter one as I have already finished reading it.

-Mario