Troubleshooting TCP connectivity problems

When two TCP processes wish to communicate, they open the connection, send the data, and then close the connection. This happens when you open a browser to the internet and connect from your mail client to the mail server, or with Telnet to your router or any other application that works over TCP.

When TCP opens the connection, it sends a request for open connection from the source port to the destination port. Some problems can occur during the establishment or closing of the application. Using Wireshark to locate and solve these problems is the goal of this recipe.

Getting ready

If you experience one of the following problems, use Wireshark in order to find out what the reason for it is. These problems can be of many types, which are as follows:

• You try to run an application and it does not work. You try to browse the internet and you don't get any response.
• You try to use your mail but you don't get a connection to the mail server.
• Problems can be due...