A common scenario of network problems is trying to access resources on a different computer over the network, e.g. copying files from a laptop to a desktop machine, backing up folders to a hard drive on another computer, sharing photos or music stored on one computer with other computers on the network etc. The following is a list of most common configuration problems.
Check the Workgroup – On each machine, right-click on My Computer, select Properties and make a note of the workgroup. In order to see each other in a peer-to-peer network, all computers must be in the same workgroup. Change all computers to the same workgroup, reboot, and try again. This does not apply to a domain-based network.
Check File and Printer Sharing – Check the network connection properties and verify that File and Printer Sharing is installed. If not, add it and reboot.
|Windows XP Local Area Connection Properties|
Supply the proper authentication – Depending on how the resource you want to access is set up, you may have to authenticate yourself first to the other computer. If you receive a dialog box asking for authentication when trying to access a share on another computer in Windows Explorer, enter the computer name you wish to access, a backslash (\), a username from that computer, and then the appropriate password in the password field.
Example: You are working on a computer called HomePC1. You are logged in as user MaryG. This user account exists only on the computer HomePC1 and is therefore called a local account.
You are using Windows Explorer to browse the network neighborhood to a computer called HomePC2 to access files on a share called Documents on that machine. You find the computer and that share, but when you click on it, you get prompted for authentication. The reason for this is that apparently the share does not allow access to anybody, but only to qualified users. It prompted your PC for authentication information and it replied with the account you’re logged in as, MaryG. Since that did not match, it asks you now for another user account.
You have a user account on the computer HomePC2 called JackS with the password 12345. To authenticate, you type HomePC2\JackS in the username field and 12345 in the password field. After pressing Enter, you are able to access the share now since JackS has rights to access it.
Alternatively, you can also use a command-line to map a network drive to the desired share on that computer. Open a command prompt and type the following command:
net use * \\HomePC2\Documents /user:HomePC2\JackS 12345
This will map the next available drive letter to the share Documents on the PC called HomePC2 and use the account JackS with the password 12345 as authentication. Windows Explorer will now show a new drive letter that points directly to that share.
In a more advanced office network there will be a domain. A domain means managing user accounts and permissions on computers belonging to the domain centrally instead of on each individual computer. This allows users to use a single user account to gain access to network resources on multiple computers on the domain and gives the administrator the ability to tightly control what type of access rights users have to what resource. If you run into problems accessing a network resource on a network that is managed with domains, you should contact the network administrator for assistance.
A gateway is the next configurable device in the chain of hops along a network path from the PC that will redirect the transmitted data to the next hop depending on its configuration. This is usually a router.
Scenario 1 – PC -> DSL/Cable modem: The gateway is on the ISP’s network and cannot be accessed or configured by the user. If everything checks out on the PC and the problem seems to be at the next hop, the ISP’s gateway, contact the ISP for assistance.
Scenario 2 – PC -> Gateway device: Log into the gateway device and verify that its public interface / the WAN link is configured properly with the values provided by the ISP, i.e. the IP address and subnet mask, gateway IP address, DNS server IP address (if statically configured) or set up for DHCP and has received this information from the ISP’s DHCP server. It is very common for cheap DSL lines that they are “on demand” connections, meaning they are only active when you need them, which is more economical for the ISP for several reasons such as bandwidth and IP address allocation. In this case the ISP usually requires you to contact them and announce that you want to initiate a connection before they will give you the necessary information. This is usually done via PPPoE (Point-to-Point-over-Ethernet). If your ISP uses this method, you will need to select the PPPoE option in your gateway device and enter the necessary user login information provided by the ISP.
Scenario 3 – PC -> Hub/switch -> Gateway device -> DSL or cable modem: See scenario 2.
Scenario 4 – PC -> Office network: Check with the network administrator to have the gateway / router checked.
Scenario 1 – PC -> DSL/Cable modem: n/a
Scenario 2 – PC -> Gateway device: Gateway devices for home and small office networks usually include a firewall of some sorts. Check the firewall rules and verify that there are no custom rules that may be blocking network connectivity. Use the reset to default option if available.
Scenario 3 – PC -> hub/switch -> gateway device -> DSL or cable modem: See scenario 2.
Scenario 4 – PC -> Office network: n/a
If everything checks out within the network and up to the gateway but fails after that, the problem most likely lies with the ISP. Contact the ISP to report the problem and get assistance. Before you call, make sure you have all the information handy that you gathered during your troubleshooting, and explain the troubleshooting steps you have already done. This will make their job easier and help resolve the issue. If this is an office network, contact the network administrator instead.
When troubleshooting computer problems, the chances are good that there may be important clues recorded in log files. For example, Windows keeps several log files where it records system, application, and security information including error messages. You can access these logs by right-clicking My Computer, selecting Manage, then navigating to Computer Management / System Tools / Event Viewer and clicking each log.
Another log to consult is the firewall log. If you have a software firewall running on your PC, open it and look for a log. If you are using a gateway with a firewall, access its admin console and look for a log. Either one will most likely have entries for blocked network traffic that will give you a clue what was blocked why.
Last but not least, if you have triple-checked that everything is configured properly but it still doesn’t work, also consider the possibility of a hardware failure. Maybe a port on your hub/switch/gateway device is bad, so try another one. Does the device even have power? Maybe its power adapter failed. Is it hot to the touch? Maybe it overheated. Unplug it for 10 minutes and let it cool down, then try again. Maybe a power surge scrambled its memory. Unplug it for five seconds, then plug it back in again and try again. Try resetting the device to factory defaults. Maybe the suspect device that you identified by process of elimination is fried altogether. Replace it with a different one and see if that corrects the issue.
Boy, that was a lot of information, wasn’t it? Hopefully you have learned a lot about the basics of networking and got a better understanding of what makes a network tick. In addition, you should now realize that troubleshooting a network connection is a pretty logical process and that there are many things you can easily check yourself to resolve the problem yourself within a reasonable amount of time.
– Alex –