Internet Access and Security

Today, we see a globalized world, where the internet is seen as a necessary evil for many people, it is in it that we suddenly have even a piece of our lives, photo albums, documentaries, materials, among others. Even so, we also have our own computer, where it can be connected to the internet or not, and in the second method, that of not being connected, it would be the most secure.

Just today, I was doing a search on the internet, through the PING commands, sending TCP / ICMP packets to see if there were any computers running on the network, through some certain IP addresses that I typed “in luck”, and I ended up finding many machines that were responding to packages.

The PING command, in the Command Prompt, sends a packet written “PING” to a specific computer on the network, which responds with a “PONG” packet when it receives the ping. Widely used to find out if it is functional on the network, however, it is possible to block the ports to not respond to requests.

If you want to do the test, do it with the Google website   for example, it responds to packages.

Soon after, I executed the command Telnet, widely used for remote access, and it happened that some of the computers that responded to PING, were D-link 500B routers. By default, these residential routers, by default, respond to all ping requests, and most of the time, a residential user does not know that he uses a router, but rather a simple "modem".

These routers can damage your life, especially if they are not configured. Quickly, by doing this, I was able to connect and log in to at least some 6 or 8 routers via Telnet, as they all had factory default user names and passwords, and had access to computers that received IP addresses through the DHCP server, which by default it is also activated at the factory, to assign IP address to the computer connected to it.

A router works on the internet as a NAT, it receives the internet, and passes it to any computer on the local network, which is your computer. On dial-up internet, this is different, there is no NAT. Your own computer is exposed on the internet, except for Windows Firewall only.

It turns out that by accessing the router, with administrator privileges, you can redirect internet ports to a specific computer, in addition, you can do PINGs on local computers, just to see which one has the windows firewall disabled. Seeing this, it is quickly possible to hack into any computer, simply because the router has not been configured correctly.

If you don't know how to configure your router or have never done this, read your manual, to see administrator passwords, how to change the default, and enter an extremely difficult password, consisting of letters, numbers and special characters, such as "@" or “+”. Never forget these passwords, although if you forget your password, you will simply have to “Reset” your router.

You can find all this in the manual, and if you don't have the manual, you can quickly find it by typing the model in  Google .

See you soon, with more safety tips!