The Networking 101 for Dummies pre-wiki Thread.

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Murrkf
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PostPosted: Fri Aug 28, 2009 16:54    Post subject: The Networking 101 for Dummies pre-wiki Thread. Reply with quote
Often we have people here who don't understand basics of networking or terminology. I was one myself when I first joined the forum, and haven't moved too far from where I was. We need a thread that deals with these basics. I can't do it as my knowledge isn't precise enough.

I am thinking that this thread can be where people can post basic information, and others can ask basic questions and get an answer. While some people's understanding of basics might mean they shouldn't be monkeying with third party firmware, I think that most can handle it if we educate them properly.

Please provide an explanation of what something is, what it does, and why one should understand it.

Please...polite, respectful discussion only. When we have a bunch of information we can collect it all, and put it in the wiki. I will give some examples in my next post. Please feel free to correct or make my responses more accurate.


Last edited by Murrkf on Sun Oct 25, 2009 0:54; edited 1 time in total
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Murrkf
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PostPosted: Fri Aug 28, 2009 17:05    Post subject: Reply with quote
An IP ADDRESS is a number composed of four groups of numbers 0-255 separated by a "." Every device on a network has to have its own IP address. Here is an example of an IP address:
192.168.7.22.

A SUBNET is a group of IP addresses that share the first three groups of numbers (when a normal subnet mask of 255.255.255.0 is used). Two devices where one has the IP address of 192.168.1.5 and the other has the IP address of 192.168.1.6 are on the same subnet. If one had an IP address of 192.168.2.6, it would be on a different subnet. Devices on different subnets cannot communicate with each other unless the subnets have routes to one another. Normally you set up different subnets so that the devices on one cannot communicate with the devices on another.

A DHCP server provides IP addresses to devices on the subnetwork, that are setup to receive an IP address automatically. You can only have ONE DHCP server on each subnet. This is why you must disable dhcp when you have more than one router on the same subnet.

A GATEWAY is a router that connects the devices on a subnet to the internet. You should only have one Gateway on any subnet.

What's an IP table?

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Last edited by Murrkf on Sat Aug 29, 2009 0:20; edited 1 time in total
DHC_DarkShadow
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PostPosted: Fri Aug 28, 2009 19:40    Post subject: Reply with quote
I've done some research and really doesn't seem to be an easy answer. I don't know, this may be something to add to Networking 102 for dumba$$'s.

How do you link subnets?

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ad5mb
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PostPosted: Fri Aug 28, 2009 22:20    Post subject: Reply with quote
I am writing a series of tutorials for my coworkers. I am planning on posting a reduced version of lesson 1 at another site.

if you don't mind, I will email you what I have so far.

P.S:

Quote:
A SUBNET is an IP address that shares the first three groups of numbers.


1) we need to talk
2) stop writing until you get an editor

2nd P.S:

A+, Network+, i-Net+, Server+, Microsoft Network Essentials certifications. Amateur Extra Class with General Radiotelephone Operators License. Instuctor trained by Uncle Sugardaddies Army. Working on CWNA.

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DHC_DarkShadow
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PostPosted: Fri Aug 28, 2009 22:40    Post subject: Reply with quote
ad5mb wrote:
A+, Network+, i-Net+, Server+, Microsoft Network Essentials certifications. Amateur Extra Class with General Radiotelephone Operators License. Instuctor trained by Uncle Sugardaddies Army. Working on CWNA.


I think you may be a little Over qualified for a dummy tut. We need it in layman's terms.

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phuzi0n
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PostPosted: Fri Aug 28, 2009 23:29    Post subject: Reply with quote
DHC_DarkShadow wrote:
I've done some research and really doesn't seem to be an easy answer. I don't know, this may be something to add to Networking 102 for dumba$$'s.

How do you link subnets?

Routes. I've helped a few people set up static routes but the question doesn't come up much. Most people stick to one big broadcast domain (subnet) wasting their bandwidth. I don't see anything about it on the wiki so I'll try to write something up soon or you can create another forum thread to talk about implementing it.

ad5mb wrote:
Quote:
A SUBNET is an IP address that shares the first three groups of numbers.


1) we need to talk
2) stop writing until you get an editor

Yeah, I don't think much can really be 'dumbed down' without becoming blatantly inaccurate. I edited the IP address definition to be a little more precise while maintaining the 'lame-un speak' feel to it but the subnet definition made me cringe. I don't know if there's any way to accurately describe subnets without explaining subnet masks which requires some knowledge of the binary AND operation.

Murrkf wrote:
What's an IP table?

Are you referring to the iptables command? It's definitely not something for beginners.

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Murrkf
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PostPosted: Sat Aug 29, 2009 0:16    Post subject: Reply with quote
ad5mb wrote:
2) stop writing until you get an editor.


That's where YOU and others come in.

I think, however, we can presume a subnet mask of 255.255.255.0....for basic understanding. The problem is, we use the term subnet all the time, and lots don't know what we are talking about. I do want to keep this as simple guide for people with little or no training....enough so that the lingo won't be a barrier.

I edited the edit so we don't have people being confused by class C subnet masks. Feel free to correct or comment on anything written.

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ad5mb
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PostPosted: Sat Aug 29, 2009 0:59    Post subject: Reply with quote
Quote:
I think you may be a little Over qualified for a dummy tut. We need it in layman's terms.


Quote:
Instuctor trained by Uncle Sugardaddies Army.


not slamming our soldiers - I was one - but have you ever heard anyone say

"You're so smart. You must be in the Army"?

as noted above, I have a tutorial prepared. It's about mesh networks, so it sort of stops suddenly and switches from WiFi for construction workers to Mesh Networks for construction workers. We have a mesh at work, and you can't find much useful info for beginners about mesh. So it needs a bit of fleshing out, and I need to tweak the images and put them in photobucket.

so, again: I can send Murrkf a .PDF of the original for evaluation. You may find tht a person who has taught for 2/3s of his life knows how to present information in an orderly format, and you won't have to reinvent the wheel.

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phuzi0n
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PostPosted: Sat Aug 29, 2009 1:08    Post subject: Reply with quote
ad5mb wrote:
"You're so smart. You must be in the Army"?

Laughing

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Read the forum announcements thoroughly! Be cautious if you're inexperienced.
Available for paid consulting. (Don't PM about complicated setups otherwise)
Looking for bricks and spare routers to expand my collection. (not interested in G spec models)
DHC_DarkShadow
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PostPosted: Sat Aug 29, 2009 4:32    Post subject: Reply with quote
ad5mb wrote:
not slamming our soldiers - I was one - but have you ever heard anyone say

"You're so smart. You must be in the Army"?



I understand totally, I was in the navy. Sorry it just came off as a little wierd, with the qualifications at the bottom.

Muurkf is right about needing the "smarter" (cause I am definitely not one of them) people coming in to correct.

Again my apologies.

phuzi0n wrote:
DHC_DarkShadow wrote:
I've done some research and really doesn't seem to be an easy answer. I don't know, this may be something to add to Networking 102 for dumba$$'s.

How do you link subnets?

Routes. I've helped a few people set up static routes but the question doesn't come up much. Most people stick to one big broadcast domain (subnet) wasting their bandwidth. I don't see anything about it on the wiki so I'll try to write something up soon or you can create another forum thread to talk about implementing it.


That would be wonderful. With "Routes" and "IPTables" you will have my complete attention. Lets just say I know enough to make me dangerous. Laughing

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lastlaugh
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PostPosted: Sat Aug 29, 2009 5:06    Post subject: Reply with quote
Seeing as this forum deals with switches and routers, what do ya'll think of having an entry on the OSI layer? I think I could do something pretty basic on it, at least on the first 3 layers if that is all we needed. Honestly, I could write a book by myself on the subject of networking. (CSU/DSU, ATM, TCP/IP, fiber, ADSL, CCNA/CCNP, several routing and switching protocols, etc.) I am pretty well versed on long haul and short haul networking, even the old promina if we decide to take it that far! I used to teach Network infrastructure for the Air Force, and have a knack for breaking it down "barney style" as we put it! Just let me know what all you want in it

I'll start with this and edit as needed:

OSI (Open Systems Interconnect)Model-

General networking is divided into 7 layers according to the OSI (Open Systems Interconnect) model. This model is just a way to visualize how the signal travels thru the network, from the very basic electrical pulses to the way it interacts with your operating system. It is divided as follows:

Application Layer
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer

The bottom three layers are the ones we deal with the most on this forum. The bottom, most basic layer is the Physical layer. This is the layer that Hubs work on. A hub is, in essence, a splice. Every bit of information that is sent or received is seen by every device on a hub. Therefore, bandwidth is wasted by sending information to devices that haven't requested it. For example, say you have a 5 port hub with 4 computers connected to it. You decide to stream music from desktop 1 to desktop 2. Desktop 1 broadcasts the music to desktop 2, but also to desktop 3 and 4. Desktop 3 and 4 didn't request this information, so they drop the packets as they come in. When you are streaming large files on a hub, you can see how this can create problems. To remedy this, most people use a switch.

Switches operate on the Data Link Layer. The data link layer utilizes a hardware encoded MAC address to determine where to send traffic. So, if you use the same setup as above with a switch, desktop 1 would see the MAC address of desktop 2 and only send the music to it, and not to desktops 3 and 4. (yes, i know about broadcast and multicast, but this is a basic tutorial). This greatly minimizes the amount of traffic being sent across a network, and is why you almost never see hubs in use anymore.

The third layer, the Network Layer, is the layer our beloved routers work on. Layer 3 devices utilize Internet Protocol (I.P.) addresses to determine where to send information. This goes beyond simple MAC addresses and gives us the versatility to "route" traffic to exactly where we want it, and keep traffic from going where we don't want it.


This is what we are referring to when we say a hub is a layer 1 device, switches are layer 2 devices, and routers are layer 3 devices.

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Last edited by lastlaugh on Sat Aug 29, 2009 15:26; edited 3 times in total
Murrkf
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PostPosted: Sat Aug 29, 2009 11:02    Post subject: Reply with quote
I will take any info that anyone wants to provide.

I certainly don't understand layers.

We also need definitions of real basics. WAN, WLAN, LAN, and...subnet masks. We could use a definition about what routing really is. NAT should be defined. Lots more I am probably not thinking of, but you might.

So go for it. Write something. We going to fish, or cut bait?

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I'm trying to teach you to fish, not give you a fish. If you just want a fish, wait for a fisherman who hands them out. I'm more of a fishing instructor.
LOM: "If you show that you have not bothered to read the forum announcements or to follow the advices in them then the level of help available for you will drop substantially, also known as Murrkf's law.."
DHC_DarkShadow
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PostPosted: Sat Aug 29, 2009 12:00    Post subject: Reply with quote
Wide Area Network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries). The largest and most well-known example of a WAN is the Internet.

WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions.

Local area network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport. The defining characteristics of LANs, in contrast to wide-area networks (WANs), include their usually higher data-transfer rates, smaller geographic place, and lack of a need for leased telecommunication lines.

Wireless LAN (WLAN) is a wireless local area network that links two or more computers or devices using spread-spectrum or OFDM modulation technology based to enable communication between devices in a limited area. This gives users the mobility to move around within a broad coverage area and still be connected to the network.

For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops. Public businesses such as coffee shops or malls have begun to offer wireless access to their customers; some are even provided as a free service.

Internet service provider (ISP, also called Internet access provider, or IAP) is a company that offers its customers access to the Internet. The ISP connects to its customers using a data transmission technology appropriate for delivering Internet Protocol datagrams, such as dial-up, DSL, cable modem, wireless or dedicated high-speed interconnects.

ISPs may provide Internet e-mail accounts to users which allow them to communicate with one another by sending and receiving electronic messages through their ISP's servers. (As part of their e-mail service, ISPs usually offer the user an e-mail client software package, developed either internally or through an outside contract arrangement.) ISPs may provide other services such as remotely storing data files on behalf of their customers, as well as other services unique to each particular ISP.

Wireless Internet Service Providers (WISPs) are Internet service providers with networks built around wireless networking. The technology used ranges from commonplace Wi-Fi mesh networking or proprietary equipment designed to operate over open 900MHz, 2.4GHz, 4.9, 5.2, 5.4, and 5.8GHz bands or licensed frequencies in the UHF or MMDS bands.

wireless access point (WAP) is a device that allows wireless communication devices to connect to a wireless network using Wi-Fi, Bluetooth or related standards. The WAP usually connects to a wired network, and can relay data between the wireless devices (such as computers or printers) and wired devices on the network.

Credit: Wikipedia

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Last edited by DHC_DarkShadow on Sat Aug 29, 2009 17:39; edited 4 times in total
lastlaugh
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PostPosted: Sat Aug 29, 2009 14:40    Post subject: Reply with quote
I'm digging thru my training manuals trying to figure out how to explain routing and subnets in basic terms. It is almost impossible to explain subnets without explaining subnetting though, and subnetting is impossible to explain without teaching binary! I think I can give NAT and the very basics about routing though.

Routing, DHCP (Dynamic Host Configuration Protocol), and NAT (Network Address Translation)-
Before the days of home routers, you had to purchase multiple IP addresses in order to have multiple computers online. However, the presence of routers running NAT and DHCP have enabled us to use as many devices as we need. Home routers work by modifying the IP addresses of incoming and outgoing traffic, to determine what info goes to what specific computer. This process is called Network Address Translation. The router is assigned an IP address by your ISP (Internet Service Provider); we'll use 10.1.1.1 for example. Your router uses this IP for its WAN (Wide Area Network) address, and reports this, and only this address to any computers on the outside of your network. It then uses DHCP, if you are using it, to issue different IP addresses to the computers in your home. The router stores the WAN IP along with the IP addresses of the computers in your home in a table in memory. (DHCP/NAT table). When a computer from inside your network, (say 192.168.1.2) requests information from www.google.com, your router remembers this, changes the ip address of the source IP (192.168.1.2) to the IP address your ISP assigned as its WAN address (10.1.1.1)and then sends the request outside your network to www.google.com. So, the only thing google sees is a request from (10.1.1.1). When google respond to this request, it sends the info to the WAN address of your router. Your router receives the info from google and checks its NAT table to see if anyone inside your network requested this information. When it see that your computer at address (192.168.1.2) requested this info, it "routes" this information directly to the computer.
Lets say that, while you are on google, a hacker at IP address 15.15.15.15 tries to access your computer. Your computer didn't request this information, so when it arrives at the WAN address of your router, it gets compared to the NAT table to determine if a computer inside your network requested it. When your router sees that no one asked for this information, it simply drops the packets and goes about its business. This process is referred to as NAT.


DNS- (Domain Name System/Server)

As mentioned previously, all computers on a routed network are assigned IP addresses. This enables the different routers on the internet to accurately route information to the proper location. However, most humans don't have the ability to remember IP addresses of all their favorite websites. So, DNS was invented. Websites on the internet are assigned domain names to enable us to remember them more easily. (For example www.google.com). This enables us to remember them more easily, but computers still use IP addresses to communicate, not domain names. What DNS does is translates domain names to IP addresses. When you type www.google.com into your web browser, a request is sent to your ISPs DNS server. Your DNS server has a table that stores websites domain names and IP addresses. It checks its table and sees that the IP address for www.google.com is actually ( 74.125.67.104 ). Try it. Type the IP address into your browser, and it will take you to the same place as when you click on the website. It then forwards the information to google's IP address.



Hopefully this is basic enough. Please let me know if I can simplify it even more and still be as detailed as possible. Please, no nitpicking. I am trying to make this as simplified as possible. We can make a more advanced entry later if warranted.

_________________
WHR-HP-G54 --(12307)--main router
WHR-G125 --(12307) -- C/B (X2)
54G ver 2.0 -- (12307) -Backup
54G v 4 (11296) - Backup
F*n 2100 (testing) (X2)
Belkin F5D8235-4
AF Active Duty- (3C251)(3P071)
Network Infrastructure Technician
Murrkf
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PostPosted: Sun Aug 30, 2009 0:52    Post subject: Reply with quote
I need to read through this again. There is a lot of accurate information, but some of it is too technical to be understood. I believe there is nothing wrong with being correct "enough" for beginners. I am the guinea pig here....if *I* can't undertand it (a very low hurdle), it's too complex. What I will try to do is take some of this correct info, and re-word it so that it is hopefully correct "enough".

The aim here is to allow people who have NO idea of what they are being told, some basic information so they can "get it". I am not seeking a completely accurate course, but will use any and all info provided. The trick is, to provide words that they will likely understand, but might only be 95% correct. For example, although WAN doesn't have to be the internet....pretty much every time we use WAN, we mean internet.

Public IPs and Private Ips should be discussed. And, although I don't think we should teach iptables, we could say what they do.

We might have to have "the absolute noob" info, followed by a more detailed explanation.

So...keep it coming.

_________________
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I'm trying to teach you to fish, not give you a fish. If you just want a fish, wait for a fisherman who hands them out. I'm more of a fishing instructor.
LOM: "If you show that you have not bothered to read the forum announcements or to follow the advices in them then the level of help available for you will drop substantially, also known as Murrkf's law.."
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