January 23, 2012

Use DHCP Reservation to Minimize Unauthorized Connections to your DLink DIR-300 Wireless Router

If you're living in a condo or an apartment building, it's so easy for your neighbors to make use of your wireless Internet connection especially if you did not configure any security settings in your wireless router. If you're experiencing slow Internet speed when you're surfing, then it could be that a few of your neighbors may be availing themselves of free Internet connection from your wireless router.

There are various ways of minimizing unauthorized access to your wireless router like for example setting up access control and using strong encryption in your security settings. But there is  yet another way by which you can control the number of computers that may access your wireless home network and this is through Dynamic Host Configuration Protocol (DHCP) reservation. I am using the DLink DIR-300 wireless router as an example but this scheme can also be implemented in other brands of wireless routers.

The scheme works by using a customized Internet Protocol (IP) addressing plan that includes few enough addresses but is able to accommodate all the computers that you expect to be connecting with your network. What you will do is to give your DLink DIR-300 DHCP server only one IP address to assign to anyone wishing to connect with your network. You will then assign the first few addresses statically to existing computers in your house and put these in the DHCP Reservation list of your DLink DIR-300 wireless router. If anyone you know wishes to use your Internet connection, then you just use the next available address and enter it together with the machine address of the wireless adapter of her computer in your router's DHCP Reservation list.

Say you have decided to use the IP address range 10.20.30.48 to 10.20.30.63 with a subnet mask of 255.255.255.240 giving you 14 usable addresses for computers in your network. You can then give the highest valid IP address (10.20.30.62) to your DHCP server for giving to anyone that wishes to connect with your network. Then you can assign the first few lower addresses to actual computers in your network and then enter them in the DHCP Reservation list of your DLink DIR-300 wireless router. You cannot use 10.20.30.48 and 10.20.30.63 because they are your network address and broadcast address respectively.

Gather first all the machine addresses of the wireless adapters of all computers in your house. Assign the first available address (10.20.30.49) to your wireless router and the next few addresses to the rest of computers in your network. If you have four computers that will actually use the network, then you would be using up the first five IP addresses in your IP address range.

Open and logon to your DLink DIR-300 web based configuration program. Click on Maintenance at the top portion of the window and then click on Save and Restore on the top left hand side. Click on the Save button and save the configuration file to your hard disk. Click on Setup at the top of the window and then on LAN Setup on the top left hand side of the configuration page. Type 10.20.30.49 on the blank opposite Router IP Address. Type 255.255.255.240 on the blank opposite Default Subnet Mask. Put a check mark on Enable DHCP Server. Type 62 on both of the two boxes opposite DHCP IP Address Range.

Go down to the DHCP Reservation and fill out four random computer names on the Computer Name column, for example computer1, computer2 and so forth. Type the next four IP addresses after the router's address on the blanks under the IP Address column. On the first four blanks under the MAC Address column, enter the machine addresses of the actual computers that are to connect to the network. In Windows computers, you can find the machine address of the computer's wireless adapter by typing ipconfig /all in a command prompt window on your desktop. Put a check mark on the left hand side of the four rows of data that you have entered. Click on the Save Settings button at the bottom of the page.

Restart all computers in your network and check that they are receiving the static IP address reserved for them. Use the ipconfig /all command in a command prompt on Windows computers to find out what IP address and subnet mask had been assigned by your router's DHCP server. If something went wrong and your laptop did not receive the correct IP address, temporarily assign it with the correct IP address using your Windows control panel and restart it so you can access your router again to make the needed corrections. You will have to use the new router's address (http://10.20.30.49) to access the configuration page of your router again. If by any chance you got confused and want to go back to the original setting, you can re-upload the original settings that you have saved in your hard disk. But you have to manually assign a temporary valid IP address, subnet mask, and gateway address (your router's IP address) to your laptop if you want to do this.

If you were able to successfully changed your settings, only one other external computer that is setup to obtain IP address automatically will be able to connect to your network. To connect a friend's laptop to your network, get the machine address of its wireless adapter and enter it together with the next available IP address on the next blank row on the DLink DIR-300 DHCP Reservation list. Put a check mark on the left side of the row and click on the Save Settings button. Now you have more control on which computers to allow access to your network. However, external computers can still connect to your network if they are manually assigned one of the unused IP addresses in your IP address range. Hopefully, not everyone knows how to do this and thus the threat of too many unauthorized external connections is at least minimized.

Read my other article on a simple IP addressing scheme for using DHCP on your wireless home network at: http://publishtoweb.blogspot.com/2011/12/simple-ip-addressing-scheme-for-using.html.

Read my other article on how to setup DHCP in your DLink DIR-300 wireless router at: http://publishtoweb.blogspot.com/2012/01/how-to-setup-dhcp-in-your-dlink-dir-300.html.

Read my other article on how to maintain connectivity with your wireless router when changing its IP address at: http://publishtoweb.blogspot.com/2012/01/how-to-maintain-connectivity-with-your.html.



January 18, 2012

Troubleshooting Vista Connection Problems in a Wireless Home Environment

The key to resolving Vista network connection problem in a wireless home environment is to familiarize yourself with how the network works when you are not experiencing problems. Thus, you would more likely be able to easily identify what is not working if you know how the network should work when you are not experiencing connection problems. In addition, the Vista operating system provides for a diagnostic tool that can guide you as to where the connection problem is and suggests actions that may resolve the problem. You can open your control panel, click on Network and Internet, then click on Network and Sharing Center to view how your computer is connecting to the Internet.

When your network is working normally, you will see three elements on the diagram that is shown on the Network and Sharing window: your computer, the name of your wireless network, and the globe that symbolizes the Internet. You may conceptually remind yourself that the globe essentially represents the network equipments in your Internet service provider. More particularly, your wireless router talks to another router in the premises of your Internet service provider. When nothing is wrong with your wireless home network, the diagram is clean and you don't see any red or yellow symbol that depicts that there is a connection problem. Your wireless network name will also be displayed if you are not experiencing any problem with your Internet connection.

The connection from your computer to your wireless router is an area that is within your control and therefore you can pretty much do whatever is necessary there to resolve your problem. The other half of the connection between your router and your Internet service provider is a shared area that you don't have absolute control of and thus what you can do there is much more limited. In addition, the closer the problem is to your computer, the more serious the problem is, meaning that if the connection between your computer and your wireless router is lost, there is no way that you can connect to the outside world.

Two things must happen for you to be able to access the Internet: your computer must be connected to your wireless router, and your wireless router must be connected to the router in the premises of your Internet service provider. The more common problem that you would be experiencing would be between your wireless router and your Internet service provider's router.

The most common way by which connection is achieved between these two routers is for your wireless router to be able to get valid Internet Protocol (IP) addresses for its use and for use in determining where information packets are to be delivered. Typically, your wireless router asks and receives an IP address that it can use for a specified length of time only and needs to renew the lease before it lapses. This renewal process can take a while to accomplish and you will experience a temporary loss of connection to the Internet. But once the process is complete, connection is quickly re-established.

You can easily find out if such is the case by looking at the log of your wireless router. When you see a series of exchanges between your wireless router's Dynamic Host Configuration Protocol (DHCP) client and the DHCP server of your Internet service provider's router, then a renewal process is happening and you pretty much can't do anything but to wait until the process has been completed. A more common situation is that your wireless router is unable to connect to its Domain Name Service (DNS) server. You can find out if such is the case when you see a red letter X on the line between your wireless router and the globe in the Vista Network and Sharing Center diagram. You can click on the red letter X mark and Vista will inform you that there is something wrong with the DNS operation in your wireless router. This can typically be resolved by opening your router's web interface and renewing the DHCP lease on your router's IP address.

When DHCP is enabled in your wireless router a similar situation can arise when for one reason or another, your computer fails to get a new IP address or fail to renew its IP address from your wireless router. You will know that such is the case when you see a yellow triangle on the line between your computer and your wireless router in the Network and Sharing window of your Vista control panel. Your wireless router will be shown as unidentified and you won't be able to access the Internet at this point. You can click on the yellow triangle to diagnose the problem and one of the actions suggested is to automatically get the required IP addresses from your router. You can click this option to resolve the problem, then wait as the diagram changes to normal as the problem is being solved.

If you want a more technical solution, you can open a command prompt in your Vista computer and run it as an administrator. Type ipconfig /all and check what IP address the wireless adapter of your computer is using. If it belongs to the 169 series of numbers, then your computer automatically assigned that address for itself, failing to find a DHCP server where it can get one that is valid for your network. Enter the ipconfig /renew command and wait for the command's results. You should see that your computer has acquired a valid IP address for your network. Check again your Vista's Network and Sharing Center diagram to confirm that your network is back to its normal operation.

It would be a good idea to wait for a few minutes and let Vista resolve the connection problem by itself before doing any troubleshooting activity. Sometimes, the problem only needs a few more time before being resolved. Try logging off and logging on again or rebooting your Vista computer first and see if the problem goes away. If nothing happens, then it is time to find out where the problem lies and then renew the DHCP lease on your router or on your computer as you determine by looking at the Network and Sharing Center on your Vista control panel.

Read my other article on working quickly while taking care of your Vista computer at: http://publishtoweb.blogspot.com/2011/12/working-quickly-while-taking-care-of.html.

Read my other article on shielding your Vista laptop from attacks with a wireless DLink router at: http://publishtoweb.blogspot.com/2011/06/shield-your-vista-laptop-from-attacks.html.

Read my other article on why microphone is not heard on the speakers of Vista laptop at: http://publishtoweb.blogspot.com/2009/03/why-cant-my-voice-be-heard-on-speakers.html.

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January 9, 2012

How to Maintain Connectivity with your Wireless Router when Changing its IP Address

The fundamental rule for local network connectivity is that computers must be in the same network, meaning they belong in the same Internet Protocol (IP) address range as defined by the network address and its subnet mask. When you change your wireless router's IP address and subnet mask, your wireless Vista laptop loses connectivity with the router.

If you disabled DHCP in your wireless router, and your Vista laptop is configured to obtain IP address automatically, then your Vista laptop cannot connect to your router when you restart it. Your Vista laptop will automatically assign one of unused IP address from 169.254.0.0 to 169.254.255.255 which is the range of automatic private IP addresses established by the Internet Assigned Numbers Authority (IANA).

If you want to connect with your wireless router again, you need to manually assign your Vista laptop with a valid and unused IP address together with your network's subnet mask and the router's IP address as gateway address. You can do this by logging on as Administrator, opening your Vista laptop's control panel, and clicking on Network and Internet.

Click on the Network and Sharing Center and on the left hand portion of the window, click on Manage network connections. Left click Wireless Network Connection, right click it, and click on Properties. Click on Internet Protocol Version 4 and then click the Properties button. Check the Use the following IP address button and enter a valid IP address, your network's subnet mask, and the IP address of your wireless router for Default Gateway. Click on OK, close your Vista control panel and restart your laptop. To continue with configuring your wireless router, open your Internet browser and type the router's IP address on the address bar of your Internet browser.

If your wireless router is setup with Dynamic Host Configuration Protocol (DHCP) enabled and your Vista laptop is configured to obtain IP address automatically, restart your Vista laptop and check if the router has given  your laptop the correct IP address. Open a command prompt in your Vista laptop and enter the command ipconfig /all. Look for your laptop's wireless adapter and make sure that its IP address is as what you expect it to be. If not, then there may be something wrong in your router's DHCP settings.

If the IP address obtained by your laptop is within the valid range of your network's IP address range, then you can just type the router's IP address on your Internet browser and open the router's web based configuration program. If not, then you can temporarily assign it with valid network addresses as described in the preceding paragraphs and restart it. Now, you can once again connect with your wireless router and correct its faulty DHCP settings.

To check if your Vista laptop is getting the correct IP address from the router, manually setup your laptop's IP address by following the steps in the preceding paragraphs and checking on the button labeled Obtain an IP address automatically and clicking the OK button. Close your Vista control panel and then restart your laptop. Perform the IP address checking procedure as described earlier using the command prompt to make sure that your laptop is receiving the correct IP address.

The IANA has set aside several blocks of IP addresses that cannot be used in the Internet and designed for use only in private networks. You can choose from any of these private IP address ranges and customize an IP addressing scheme for your network which will accommodate only a small number of computers using a suitable subnet mask. You can look for IP address tables for these IP address blocks in the Internet and select an IP address range that you can use in your home network. You can then use the lower numbers of this range for static assignment by your router's DHCP server and the higher numbers for dynamic assignment to the rest of computers in your network.

If you find it difficult to work in wireless mode, you can directly connect your laptop to your wireless router using the LAN cable supplied when you bought your wireless router. Connect one end of the cable to the RJ-45 slot in your laptop and the other end to any one of the LAN ports of your wireless router. Now all you have to worry about is that the IP address your router is using and the IP address of your Vista laptop are within the same valid IP address range as determined by your network's subnet mask. Once you have determined that your router's settings are in order, you can disconnect the LAN cable and work in wireless mode again.

The important thing to remember is that computers in a network must share the same network address for them to be able to communicate locally. Routers find out the network address by performing a mathematical operation on the binary equivalents of the IP address numbers and their subnet mask. The resulting product is the network address to which the computer belongs to which is the lowest number in the range that appears in the IP address table when using a particular subnet mask. In performing their function, routers are not really interested in particular IP addresses of computers but only concerned with the network address and the IP address of the routers that belong to that network.

Read my other article on a simple IP addressing scheme for setting up DHCP on your wireless home network at: http://publishtoweb.blogspot.com/2011/12/simple-ip-addressing-scheme-for-using.html.

Read an article on how you can recover seamlessly from your laptop's hard disk crash at: http://laptopwriting.blogspot.com/2011/03/how-you-can-recover-seamlessly-from.html.



January 2, 2012

How to Setup DHCP in your DLink DIR-300 Wireless Router

The DLink DIR-300 wireless router has the Dynamic Host Configuration Protocol (DHCP) server enabled by default. The router is configured to use the 192.168.0.0 network address with the router having 192.168.0.1 as Internet Protocol (IP) address using 255.255.255.0 as the subnet mask. This means that there are 254 available IP addresses that can be used to enable computers to participate in the network.

To limit the number of devices that can join the network, you can use a customized network address range from any of the private address blocks defined by the Internet Assigned Numbers Authority (IANA). Using an appropriate subnet mask, you can create a small network that can accommodate the maximum number of computers that you estimate will be joining your network simultaneously. You can use an IP address table that can be found in the Internet to specify a small range of IP addresses with its corresponding subnet mask that you can use for your network.

Once you have determined the correct range of IP addresses to use, you can then divide the IP address numbers into two parts: one part for computers that are to be assigned static addresses and another part for computers that will be assigned dynamic addresses. The last step is the setting up of the DHCP service in your router to reflect the decisions that you have made regarding IP address assignment in your network.

Assigning static IP address means that a computer will receive the same IP address every time that it requests an IP address from the DHCP server. This is implemented in the router by making IP address reservations on the spaces provided on the appropriate configuration page in the router's settings. Computers determined to receive static IP addresses will not suffer from the problem of having all IP addresses being used up by computers seeking network connection.

Computers receiving dynamic IP addresses may suffer from the problem of not being able to join the network because of lack of available IP address that can be assigned to them. Their IP address may change as they are given the next available address once they ask for one from the router. Dynamic IP address assignment is implemented in the router by supplying the router with a range of IP addresses that can be allocated to computers seeking connection to the network. This is implemented by filling the required blanks on the Local Area Network (LAN) setup page on the router configuration web based interface.

Computers that should be assigned static IP addresses are the critical computers in the house like Dad's and Mom's computer as well as any computer that provides services to everyone like a multimedia server or a LAN printer. Also to be given static IP address assignments are computers that are strongly secured whose operating system and security protection are updated. MAC computers, Linux systems, and Windows computers from the Vista version and above may be included in the computers that may be given static IP addresses.

Those that are to be provided with dynamic IP addresses are those Windows computers that are older than the Vista operating system or Vista systems that are not securely protected. Computers belonging to children, grandpa and grandma, and teenagers should be included in the list that should receive dynamic IP addresses. Of course computers belonging to house guests are to be assigned dynamic IP addresses.

The first part of the job is to gather the physical addresses of the wireless adapters of all computers that are to be assigned with static IP addresses. The next step is to allocate the lower numbered addresses to the wireless physical addresses of computers that need to be given static IP addresses. The remaining IP adddresses in the range will then be allocated for distribution as dynamic addresses.

The important data that should be in order are the following: the IP address and the subnet mask to be assigned to the wireless router which should be the lowest IP address in the range or the network address plus one; the wireless physical address of all computers to be assigned static addresses with their corresponding IP address allocation; the range of IP addresses to be distributed as dynamic IP addresses.

Open your DLink DIR-300 configuration web based interface in your Internet browser. Before changing any setting on your DLink DIR wireless router, be sure to save first the current router's settings on your laptop using the Maintenance Save and Restore page of the router's configuration settings. Click on Setup and then LAN Setup and enter the IP address and subnet mask to be assigned to the router. Make sure that the Enable DHCP Server is checked and then enter the range of the last numbers of IP address to be assigned dynamically by the router. This is the range of the IP address numbers that are left after some computers have been allocated the lower numbered IP addresses.

On the DHCP Reservation portion, enter the computer name, IP address, and the wireless physical address of each computer that are to be assigned static IP addresses. Put a tick mark on each line of the blanks that you have filled out. The computer name field is for reference purposes only and need not be the same as the actual computer name, You can use any name that will uniquely identify the computer that you are assigning IP address to. Click on the Save Settings button and wait for the configuration page to come back.

Restart all computers in your network and check if the IP addresses assigned to them are what you expect them to be. Computers that are to receive static addresses should reflect the correct address when you check them in the command prompt using the ipconfig /all command. Those computers that are to be assigned dynamic address should receive one in the range of addresses you have given the DHCP server to distribute.

You have to use the new router's IP address to access again the router's configuration page. If something goes wrong and your laptop did not receive a valid IP address, you can manually assign it the IP address and subnet mask using your Vista laptop's control panel and access the router again for making settings corrections. Correct all configuration errors until all computers are receiving the correct IP address that they should receive.

Read my other article on Internet Protocol addressing for setting up DHCP on your DLink DIR-300 wireless router at: http://publishtoweb.blogspot.com/2011/12/internet-protocol-addressing-for.html.

Read my other article on simple IP addressing scheme for using DHCP on your home wireless network at: http://publishtoweb.blogspot.com/2011/12/simple-ip-addressing-scheme-for-using.html.

Read my other article on how to maintain connectivity with your wireless router when changing its IP address at: http://publishtoweb.blogspot.com/2012/01/how-to-maintain-connectivity-with-your.html.