Most users use TCP/IP, but what is it really… And what do you do when it breaks. (includes steps to reset TCP/IP back to its orginal state)

TCP/IP is described by Margaret Rouse, Webopedia, with a sprinkle of Rob, as follows:

TCP/IP, pronounced as separate letters “T-C-P-I-P” (not TaaKaaPaaa eipp) is short for Transmission Control Protocol/Internet Protocol.

TCP/IP is the suite of communication protocols to connect host on the Internet and Network, and built into most operating systems today, making it the de facto standard for transmitting data over the network.

TCP/IP is a two-layer program. The higher layer, (TCP) Transmission Control Protocol, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets back into the original message. The lower layer, (IP) Internet Protocol, specifies the format of the packets, also called datagrams, and handles the address part of each packet so that it gets to the right destination.

Most networks combine IP with a higher level protocol TCP, which establishes a virtual connection between a destination and a source.

You may notice, your computer is assigned an IP address. This is the identifier on a TCP/IP network that makes communication possible.  Either statically assigned or via DHCP, each computer is given a unique IP address and for isolated or private networks, might look like (192.168.1.101). You can check out your assigned IP address by going to the command prompt and typing “ipconfig”. For more details on the network configuration assigned to your network adapter, including the IP address, subnet mask, default gateway, and Windows Internet Naming Service (WINS) and DNS configuration. Type “ipconfig /all“

TCP/IP routes messages based on the IP address of the destination. Each gateway computer on the network checks this address to see where to forward the message. The format of an IPv4 address is a 32bit numeric address written as four numbers separated by periods. Each number can be 0 to 255. In the example above 192.168.1.101 represents an internal\Private IP address and is in the 32bit numeric address scheme.

TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as Web page) by another computer (a server) in the network. TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point or host computer. TCP/IP and the higher-level applications that use it are collectively said to be “stateless” because each client request is considered a new request unrelated to any previous one (unlike ordinary phone conversations that require a dedicated connection for the call duration). Being stateless frees network paths so that everyone can use them continuously. (Note that the TCP layer itself is not stateless as far as any one message is concerned. Its connection remains in place until all packets in a message have been received.)

Many Internet users are familiar with the application protocols that use TCP/IP to get to the Internet. These include the World Wide Web’s Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Telnet (Telnet) which lets you logon to remote computers, and the Simple Mail Transfer Protocol (SMTP ) for email.

Okay, you know what TCP/IP is, and how it’s used to communicate on the network. But what do you do when it’s broke, and doesn’t work anymore.

Sometimes TCP/IP may become damaged or corrupted and Internet connectivity problems can often occur due to malware, virus, misconfiguration, and/or corrupted networking software installation.

When this occurs, packets don’t properly get transferred over the network even though it may seem you’re connected to the internet.

Some symptoms may include the following:

When you start Internet Explorer, you may receive an error message: “The page cannot be displayed”

In addition, you may receive one of several other error messages while using the “ipconfig” command:

“An error occurred while renewing interface ‘Internet’: An operation was attempted on something that is not a socket”
“An error occurred while renewing interface Local Area Connection: the requested service provider could not be loaded or initialized.”
“The attempted operation is not supported for the type of object referenced.”
“The operation failed since no adapter is in the state permissible for this operation.”

If you cannot connect to the Internet \ Network and you have tried all other methods to resolve and remediate the problem, its possible TCP/IP might be corrupt and is causing the issue

You can reset your TCP/IP back to its original state by using the NET Shell utility. (NETSH).

The reset command is available in the IP context of the NETSH util. Here are the steps to reset the TCP/IP manually.

1. To open a command prompt, click Start and then type CMD in the Search programs and files.
2. Right-click CMD.exe icon in Programs and choose Run as administrator.
3. When the User Account Control box pop up, click Yes.
4. At the command prompt, Type the following command and then press ENTER: netsh int ip reset c:\resetlog.txt
5. Reboot the computer.

When you run the reset command, it rewrites two registry keys that are used by TCP/IP. This has the same result as removing and reinstalling the protocol. The reset command rewrites the following two registry keys:

SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\

SYSTEM\CurrentControlSet\Services\DHCP\Parameters\

To run the manual command successfully, you must specify a file name for the log, in which the actions that netsh takes will be recorded. When you run the manual command, TCP/IP is reset and the actions that were taken are recorded in the log file, known as resetlog.txt in this article. The example, c:\resetlog.txt, creates a path where the log will reside. If the specified log file already exists, the new log will be appended to the end of the existing file.

Winsock (the Windows Sockets API) defines how software should access network services, especially TCP/IP. It defines a standard interface between TCP/IP client appliactions (such as an FTP client or a web browser) and the underlying TCP/IP protocol stack. Its possible this may need reset to its default state. To repair Winsock back to its original state complete as follows:

1. To open a command prompt, click Start and then type CMD in the Search programs and files.
2. Right-click CMD.exe icon in Programs and choose Run as administrator.
3. When the User Account Control box pop up, click Yes.
4. At the command prompt, Type the following command and then press ENTER: netsh winsock reset

Note: If you’d like to generate a log file of the changes, append a logfile path to the above command, i.e.: “netsh winsock reset c:\winsockresetlog.txt”. Changes will be appended to the end of the log file if it exists.