What I am about to tell you should be used primarily for learning and education. Certainly not for any dubious activities. It is possible to connect to another computer through the internet and browse through their directory structure, update and copy the file etc. Before you can connect you are prompted for a login and password so obviously (and preferably) you need the other person’s explicit co-operation and consent.
If you try to login without consent and approval, it is deemed as hacking. Still, if your intention is neat, meaning you just want to probe and not damage, then you are a white hat hacker. But if you want to hold the other person hostage, then you are deemed a black hat hacker.
Let say you have a home computer which acts as the main server, meaning it contains all the data etc. and you use another computer when you travel, then it is possible for you to connect to the home computer using these commands.
Say you know the ip address of the remote machine, then to connect using Telnet use the following address.
Telnet uses a specific port to connect – Port 23. So before we can connect, we need to ensure that this port is open and accessible.
To check for this and other open ports, there is another cool utility available.
Nmap is fairly easy to install and ridiculously simple to use. This utility was in fact shown being used in the movie Matrix where one of the girl protagonist scans a computer for open ports using Nmap before launching intruding attacks.
So how would you go about using all this to connect to another computer.
Before we can connect using Telnet, we need to scan the remote computer for open telnet ports. Download and install nmap. Enter the ip address of the remote machine and use one of the options available for quick scanning. This utility would give you a list of all the open ports of the remote machine.
You can find the IP address by executing the command ipconfig in the command prompt window. Remember the ipaddress that you see locally might be different from what shows up on the internet because your ISP alots a mirror address. The question is how do you go about finding the IP address of the other person? Either the person tells you you dig it out yourself. Lets say the other person uses Yahoo mail. If you have that person respond you using Yahoo mail, then you can view the originating IP address using the email headers.
This abbreviation stands for File Transfer Protocol and does exactly that. Telnet may allow you to enter another machine but you cannot copy or put files there from the local machine to the remote machine. To do that you use something like FTP. This utility uses port 21 so you need to make sure its open and accessible. You can use the same id/passwd as Telnet for using this utility.
Netstat tells you the active and passive network connections to your computer. Execute this command in the command prompt of your computer while you have Google search engine open in the browser. See the connection to Google show up in the command prompt when you execute this command. Also, use something like c:\netstat -n. This will convert all the addresses to their numeric value i.e. IP addresses.
You can find the help on executing the all the above commands by using a ‘-h’ in front of the command. For instance, to find out all the options available, run Netstat like:
After you login, what all you can do is a topic of another discussion. Good luck trying all this.