How to Detect Web Servers

Look for the Web service on the local computer. If you have access to the machine that you wish to check for Web servers, look to see if a Web service is installed and running. If the computer is running Windows, click on the Control Panel and select Services. Windows runs Internet Information Services for its Web server. On a Unix/Linux box, make sure you are logged in as root and in a command window, type 'netstat -tap |grep LISTEN' and press 'Enter.' This will display all services running at the time, including HTTPD (HTTP daemon or service) used by Apache Web servers.
Type the IP address or DNS (Domain Name Service) name into a Web browser. If you know either identifying piece of information, you can type it into a Web browser. Note that the Web server needs to be running on the default port of 80 in order for this method to work. A port is how network services access a server. Typically, services have default ports on which they operate, with the default for Web services being port 80. Typing in the IP address of a server in a Web browser will work, but if the port has been manually changed to something other than port 80 (unless you know what port it is) this method won't work. To specify a port other than 80 via a Web browser, type the IP address and then follow it with :XXX with XXX being the port number. An example of this format is 129.219.13.81:2112 with the number following the colon being the port number.
Run a port scanner. As mentioned above, port 80 is the default port in which a Web server operates. If you don't want to go through ports 1 through 65,000 manually, you can run what's called a port scanner. This software will 'listen' to a server which you specify by IP address or DNS name and determine what services are running on what ports. This way, if someone has enabled a Web server on port 2112 or another port, the port scanner will detect it. This method is popular if you want to detect Web servers that you don't have physical access to.
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