
The answer to the Media Access Control In recent weeks I have received quite a bit 'e-mails about Ethernet cards, both wired and wireless, and more specifically, about Media Access Control (MAC) addresses. I think the main reason that I have received so many questions about Ethernet cards and MAC addresses are people who try to protect their wireless home networks and their desire to use MAC address filtering. This type of filter can be configured in a wireless network to allow or deny specific computers to use or connect to the wireless network, according to the MAC address.My first thought was to write an article just about MAC addresses and wireless Ethernet. After thinking about it I decided to look into this and go over some specific information about Ethernet cards and communication.Different way to find your MAC Address And More There are several ways to find your Ethernet and communications protocol information. Many Ethernet card manufacturer has a proprietary software that can reveal this information, but that work differently depending on the manufacturer. So we want to use Windows 2000 and XP utility "ipconfig", since this is available in most Systems.First Windows, go to "Start" -> "Run" and type "cmd" without the quotes. Then press the enter key. At the command line type "ipconfig / all", again without the quotes. Actually, just typing ipconfig without the / all works, but only wants to provide all information regarding your network cards statements. An example of what one might see by typing "ipconfig / all" command is followed with each item commented in green characters: Fault Tolerant Computer System Availability and highly There are several ways to find your Ethernet and communications protocol information. Many Ethernet card manufacturer has a proprietary software that can reveal this information, but that work differently depending on the manufacturer. So we want to use Windows 2000 and XP utility "ipconfig", since this is available in most Systems.First Windows, go to "Start" -> "Run" and type "cmd" without the quotes. Then press the enter key. At the command line type "ipconfig / all", again without the quotes. Actually, just typing ipconfig without the / all works, but only wants to provide all information regarding your network cards statements. An example of what one might see by typing "ipconfig / all" command is below: Output of "ipconfig / all" Name Windows IP Configuration Host Command. . . . . . . . . . . . : Home Computer This is the name of the computer, usually defined during the installation of Windows. However, it can be changed after installation.Primary Dns suffix. . . . . . . : Join a domain.comIf your search on the network computer as a Microsoft Windows domain this entry may contain the type name domain.Node. . . . . . . . . . . . : Node Type may say Unknown UnknownThe, or peer-to-peer, or in some cases "hybrid". This is a setting that has to do with the Internet services of Windows name used in some types of networks.IP Windows Domain Routing Enabled. . . . . . . . Router NoThis mines deterministic setting if Windows XP or 2000 will function as an IP. If you have two or more network cards you can set the system to act as a router, forwarding communications requests from one network to another. Windows 2000 can be configured to do this quite easily, Windows XP will need a registry Proxy enabled modification.WINS. . . . . . . . : Proxy NoWINS is another setting that is related to "Node Type" we discussed earlier. It is not normally a desired setting in a home or small office, or new types of Microsoft Windows domains.Ethernet Connection adapter wireless network 2: If you have multiple Ethernet (network) cards in your system, as I do in this laptop , you'll have more listings. This seems to be a second Ethernet card, internal wireless Ethernet card.Description. . . . . . . . . . . Broadcom 802.11b / g WLANThis is the description of the Ethernet card, usually the manufacturer's name and / type of Ethernet card. In this case, it is a wireless card Broadcom Ethernet integrated in my address laptop.Physical. . . . . . . . . 00-90-4B-F1-6E-4AAnd here we have the MAC address. The MAC address is a 48-bit hexadecimal code and is suppose to be a unique address. This is because each 48-bit number or a letter in hexadecimal represents 8 bits. The hexadecimal numbers vary from 0,1,2,3,4,5,6,7,8,9, A, B, C, D, E, F. 6 are alpha-numeric codes so 6 * 8 = 48 (bits). The first 3 codes identify the manufacturer of the card and the remaining codes are used to create a unique number. Theoretically there should never be a card with the same MAC address on a local network. However, there are some exceptions. There are software tools that let you change the code. In fact, this is a step some hackers take to attack other systems on a local network. I say local network because MAC addresses are routable between network segments. By spoofing this address, you can impersonate another machine on the local network. The traffic was tied for the intended target can be redirected to the hacker's machine. This is the address you should then use to compile a MAC address, physical address or a table when you set the wireless access point to support the MAC address filtering.DHCP enabled. . . . . . . . . . . : YesDHCP, or Dynamic Host Control Protocol, if enabled means your computers IP address is obtained from a DHCP server on you network. The DHCP server could be your wireless access point, cable / DSL router, cable modem, or a server on the network. So, if a DHCP server is not enabled on your network, your computer operating system will automatically generate a random IP address within a predetermined range Certain. This means you could connect a group of networked systems together without having to manually assign the IP address settings.IP. . . . . . . . . . . . : Parameter 192.168.0.117This gives you your current IP address. The address above is what is called an address "private". There are certain classes of IP addresses that were set aside for private use. This means that for the internal network, local or private home or office. These addresses are not, or should, be reachable on the Internet. The streets of the Internet are called "valid" IP addresses. The cable / DSL router or cable modem has a valid IP address to the interface "outside" network. The external interface may be the phone line or cable TV cable.Subnet Mask. . . . . . . . . . . : 255.255.255.0The subnet mask is a special number, or in a certain sense, the filter, which breaks your IP address, in this case the private IP address, in certain groups. IP addresses and subnet mask can be a complicated issue and would require an entire article to go over.Default Gateway. . . . . . . . . : Default Gateway 192.168.0.254The, IP addresses mentioned above, is the IP address of the device that will route the request, as seeking when you try to browse a Web site, the Internet. It 'sa bit more complicated than that though, as a gateway or router can route traffic to different networks, including other private networks. At home or small office, this gateway most likely is the cable / DSL modem or server router.DHCP. . . . . . . . . . . : 192.168.0.49The DHCP server, remember we talked a bit 'above it, is the device that assigns your computer an IP address and other information. DHCP server can assign all kinds of information such as default gateway, Domain Name Server (DNS), IP address, Subnet Mask, Time Server, and much more.DNS server. . . . . . . . . . . : 192.168.0.49, server 64.105.197.58DNS internal or external servers that resolve the fully qualified domain names (FQDN), examined how http://www.defendingthenet.com to IP addresses. This is because computers do not actually send your request using the domain name, using the IP address assigned to the FQDN. For most home or small office, the primary DNS server is the IP address of the cable / dsl router. The Cable / DSL Router to query external DNS servers on the Internet for the effective resolution of the FQDN to IP address. The address 192.168.0.49 is an internal device on my private network whereas the 64.105.197.58 is an external public Internet DNS servers and is only present in case my router has trouble performing DNS resolution tasks.Lease obtained. . . . . . . . . . : Sunday, March 19, 2006 06:38:16 PMThis information tells you when your computer has received its IP address and other information from a DHCP server. You will notice that says "Lease Obtained", is because most DHCP servers only lease the IP address to you from a pool of available addresses. For example, your pool may be 192.168.1.1 to 192.168.1.50. So your DHCP server has 50 IP addresses to choose from when assigning your computer its IP address.Lease Expires. . . . . . . . . . : Wednesday, March 29, 2006 09:38:16 PMWhen the IP address assigned by DHCP server will attempt to lease rent is due is the same or another IP address. In general, this function can be changed on the DHCP server. For example, on some fully functional DHCP server, you can configure the lease never expires, or expire within one day and so are Sun on.Why MAC addresses some important and how Do They WorkTo return only one MAC address. You might think that IP addresses are the most important thing when it comes to communication network. The reality is that MAC addresses are very important because without them computers would not be able to communicate over Ethernet networks. When a computer wants to talk to face with another computer on a local network, make a broadcast request, or ask a question of who owns a particular IP. For example, the computer may say "Who is 192.168.0.254." Using the information above, my default gateway is 192.168.0.254 and replies "I am" 00-90-4B-F1-6E-4A "192.168.0.254". Please see its MAC address. This MAC address then goes into what is called Address Resolution Protocol (ARP) table on the computer. You can view this information by going to the command prompt like you did above and typing "arp-a". You can get information like the following: Internet Address Physical Address Type192.168.0.49 00-12-17-5c-a2-27 dynamic192.168.0.109 00-12-17-5c-a2-27 dynamic192.168.0.112 00 - 0c-76-93-94-b2 dynamic192.168.0.254 00-0E-2E-2e 15-61 dynamicHow a hacker can use MAC addresses In A AttackYou notice the IP addresses and MAC addresses to their right. Without this information, without the MAC address would not be reading this article right now. MAC addresses are not assignable as IP addresses. They work on the LAN or private. However, devices on the Internet to perform the same tasks. Routers and switches maintain a list of their colleagues MAC address devices such as computers and devices on your home or office. I have already said that the MAC addresses can be modified to redirect requests. For example, if I were on the office network and had a web server that has taken your personal information as input, I could tell your computer to go to my laptop for web broadcasting my MAC address tied to the real web server IP address. I want to do this when the computer asked "Who is the" real web server "". I could set up a fake web server that looks just like the real thing, and start collecting information that the real web servers normally collect. You can see how dangerous this can be.ConclusionThere are many other easy ways you can find the MAC address, but can be a bit 'confusing if you have more than one internal network card. Most external USB or PCMCIA wired and wireless Ethernet cards have their MAC address printed on them. Where the wired or wireless network card inside your computer are, as discussed in laptops, the MAC address is sometimes printed on the bottom of the laptop. Even Desktop systems cards that are inserted in the PCI slot has the Ethernet MAC address printed on card.You may reprint or publish this article free of charge as long as the bylines are included.Original URL (The Web version of the [EXTRACT] The answer to the question Media Access Control In recent weeks I have received quite a bit 'e-mails about Ethernet cards, both wired and wireless, and more specifically, about Media Access Control (MAC) addresses. I think the main reason why I got so many questions about Ethernet cards and MAC addresses is people trying their wireless networks for home and their desire to use to set the MAC address filtering. This type of filtering in wireless networks can be configured to allow or deny specific computers or use to connect to the wireless network, according to the MAC address.My first thought was to write an article only to MAC addresses and wireless Ethernet. After thinking about it I decided to look into this and go over some specific information about Ethernet cards and communications products . Different ways to find your MAC address and More There are many ways of searching for your Ethernet and communications protocol information. Many Ethernet card manufacturer has a proprietary software that can reveal this information, but they function differently, depending on the manufacturer. We use Windows 2000 and XP "ipconfig" utility is available, as in most Windows operating systems Systems.First go to "Start." -> "Run" and type "cmd" without the quotes, then press the Enter key on the command line "ipconfig / all", again without the quotes are really just .. ipconfig without the works of the / all, but only give information on the network card An abbreviated example of what you , you can see the "ipconfig / all" command below with each item commented in green. fault tolerant and high availability computer system There are several ways to search for Ethernet and protocol information. Many Ethernet card manufacturer has a proprietary software that can reveal this information, but they function differently, depending on the manufacturer. We use Windows 2000 and XP utility "ipconfig" is available, as in most Windows operating systems Systems.First, go to "Start . "->" Run "and type" cmd "without the quotes, then press the Enter key. on the command line" ipconfig / all ", again without the quotes. In reality, not just type ipconfig / all, but give only abbreviated information on the network adapter. An example of what you know by clicking the "ipconfig / all" command, see: the output of "ipconfig / all" command Windows IP Configuration Host Name ....... .....: Home Computer This is the name of the computer, usually defined during installation of Windows, however. to change the suffix installation.Primary .......: Domain.comIf your computer participates in a network as a Microsoft Windows domain, this title contains the type name can domain.Node UnknownThe ....... Node Type may say Unknown, or peer-to-peer, or in some cases "hybrid" There setting that is enabled with the Windows Internet Naming Service in certain types of Windows-Domain Routing: ...... networks.IP is used ........: NoThis setting determines whether Windows XP or 2000 functions as an IP router, if you have two or more network devices, you can serve the settings of your system as a router forwarding .. communication requests from one network to another Windows 2000 can be configured to perform this operation Quite simply, Windows XP is a proxy enabled ........ modification.WINS registry must: NoWINS is a proxy. other setting that is related to the "Node Type" we talked about is not usually a desired setting in a home or small office, or new types of Microsoft Windows domains.Ethernet Connection adapter wireless network 2: If you have multiple Ethernet (network cards) on your system, as I do in this laptop, you have several offers. This is done to the second Ethernet card, a wireless Ethernet card.Description be internal ...........: Broadcom 802.11b / g WLANThis is the description of the Ethernet card, usually the name / manufacturer and type of Ethernet card, in this case it is a wireless card Broadcom Ethernet address in my laptop.Physical. up .........: 00-90-4B-F1-6E-4AAnd here we have the address MAC The MAC address is a 48-bit hexadecimal code and is likely to be a completely unique address .. It is 48 bits, since each number or letter in hexadecimal represents 8 bits. Hexadecimal numbers range from 0.1, 2,3,4,5,6,7,8,9, A, B, C, D, identify E, F. 6 are alpha-numeric codes so 6 * 8 = 48 (bits). The first 3 codes the card and the rest of the code used to create a unique number. Theoretically, it should never board with the same MAC address on the local network to be. There are some exceptions. There are software tools that let you change the code. In fact This is to take a step some hackers to other systems on a local network connection. I say local network because MAC addresses are not assignable between network segments. spoofing With this address, you can take on a different machine on the local network . traffic was tied for the intended purpose, can be redirected to the hackers computer. This is the address that you could also use a MAC address or physical address to populate the table when you set the wireless access point to support the 'MAC address filtering.DHCP Enabled ...........: YesDHCP, or Dynamic Host Control Protocol if enabled means your computers IP address from a DHCP server on the network, provided that the server DHCP, the wireless access points, cable / DSL router, cable modem or a. server on the network. Furthermore, if a DHCP server is not enabled on your network, your computer operating system to automatically generate a random IP address within a some predefined interval. This means that you could have a group of network systems together without manually enter the IP address settings.IP ............: 192.168.0.117This parameter gives you your current IP address, the address above address is a so-called "private" .. you are certain classes of IP addresses, the abolition of the set to private. What this means for your internal, local or home network or office. These addresses are not, or may not be reachable on the Internet. Internet locations known as "valid" IP addresses. Cable / DSL router or cable modem has a valid IP address to its "" external network interface . The external interface may be a telephone or cable TV cable.Subnet his mask ...........: 255.255.255.0The subnet mask is a special number, or a filter in the sense that breaks your IP address, in this case the private IP address, in some groups of IP. address and subnet mask can be a complicated matter and would take a whole article over.Default Gateway ......... vai to: 192.168.0.254The default gateway, the IP addresses of the above, the IP address of the device, the routing of the request, such as when you try to browse a Web site on the Internet. It 'sa bit more complicated so, however, such as gateways or routers may traffic to different networks, including other private networks at home or small office, this gateway is more likely that your cable / DSL modem or router.DHCP Server ...... .....:. 192.168.0.49The DHCP server remember, talked a bit 'above it, is the device that assigns your computer an IP address and other information from the DHCP server to assign all kinds of information such as, . default gateway, domain name server (DNS), IP address, Subnet Mask, Time Server, server, and much more.DNS ...........: 192.168.0.49 is 64.105.197.58 DNS server internal or external servers, domain names (FQDN), such http://www.defendingthenet.com, resolve IP addresses. This is because computers do not really want to transfer your domain names using the IP address that the FQDN. after for most home or small office, the primary DNS server IP address from cable / DSL router. Cable / DSL Router to query an external DNS server on the Internet for the effective resolution of the FQDN to perform IP address. 192 168 .0.49 The address is an internal private on my network, while the exterior 64.105.197.58 public Internet DNS server is available and has received only If my router problems of implementation of the DNS resolution tasks.Lease ........... Sunday, March 19, 2006 06:38:16 PMThis information tells you when you receive your computer's IP address and other information from a DHCP server, you will notice that says "Lease Obtained", because it is the most DHCP servers only lease the IP address to you from a pool of available addresses. For example, your pool will be 192,168. 1.1 to 192.168.1.50. So your DHCP server has 50 IP addresses assigned to your computer, select the address. IP Lease Expires ..........: Wednesday, March 29, 2006 09:38: 16 PMWhen the IP address that is assigned by DHCP lease expires, will try to rent the same or a different IP address. This function can be changed in the rule to the DHCP server. For example, on some fully functioning DHCP server, you can time the lease is never, or will expire within a day and so on.Why MAC addresses are so important and how to jump back WorkTo only the MAC address for a while. 'You may think that IP addresses are most important thing when it comes to communication network. The reality is that MAC addresses are very important, because without them not to communicate with computers in a position of Ethernet networks. If a computer wants to talk to another computer over a network local, it is a broadcast request or a question, which placed a particular IP address, for example, you can tell your computer .. "Who is 192.168.0.254" With the information above, my default gateway is 192.168.0.254 and responds: "I am", 00-90 4B-F1-6E-4A "192.168.0.254". it sends its MAC address. The MAC address is then placed in a so-called Address Resolution Protocol (ARP) Table of computers. You can view this information by going to ask how you did above and typing "arp-a" get to see information like the following:. Internet Address Physical Address Type192.168.0.49 00-12-17-5c- 00 A2-27 dynamic192.168.0.109 5c-12-17-27 A2-00-0C-76-93-94-dynamic192.168.0.112 B2 dynamic192.168.0.254 00-0E-2E-2e 15-61 dynamicHow A hacker can use MAC addresses into a AttackYou remember IP addresses and MAC addresses of their right. Without this information without the MAC address would not be reading this article right now. MAC addresses are not assigned as the IP address. is Local or private work. However, see the devices on the Internet the same tasks. routers and switches is a list of their colleagues device MAC address is just like the computers and devices in your home or office network. I have already said that the MAC addresses be modified to divert your calls. For example, if I were on an office network and had an internal Web server, the personal data as input was, I can tell the computer to my laptop to the website to go with the transmission from my MAC address tied to the real IP address of the web server. I would do this if you ask your computer "Who is the" real web server. "" I could turn on a fake web server, just like the real watch, and collect the information that the web server Real normally collect. You can see how dangerous this can be.ConclusionThere are many other ways that you can easily find the MAC address, but can be confusing to be, if you have more than one internal network card. The Most external USB or PCMCIA wired and wireless Ethernet cards are printed on their MAC address. Where the wired or wireless network card inside your computer, such as, for example, laptops, l ' MAC address is sometimes printed on the bottom of the laptop. Even the PCI cards in desktop systems are connected, have the MAC address of Ethernet can be printed or reprinted card.You publish this article free as long as the bylines URL included.Original (the web version of