Gibson Research's Shields Up - is a free online security scanning tool that tests your network externally from the Internet side. It allows you to see what is open to your network through your firewall.
- When you go to the Gibson Research Shields Up website your are presented with the first page which is a standard disclaimer and information. It will also provide you with the machine name that your network presents to the Internet:
- You have several choices that are not apparent. This example is going to check "All Service Ports". This is all the well-known TCP/UDP ports exposed to the Internet:
- After the scan is completed, a Port grid will be displayed. Red indicates ports that are open, Blue are responding to probes but are closed and Green are closed and not responding to probes. Green is considered Stealth mode. The following scan shows that my network is running in Stealth mode. If you hover your cursor over any one of the blocks on the grid, it will show the Port number and information.
- You can also select specific ports to scan by selecting "User Specified Custom Port Scan". You have to enter in the port first, in this example I was scanning the SIP port 5060 and SIPs 5061.
- Messenger Spam sends 4 small UDP packets to check if your network allows Port 135 through. If it does and you are running Windows Messenger Internet server then 4 small pop-ups will occur.
- Browser Headers displays information that the browser is sending to web servers.
- Lookup Specific Port Information provides information on what a port is registered for use as. This is useful if one of your ports are open and you don't know what it is used for. This query is for Port 443 (HTTPS):
Scanning your network is important to prevent hacking attempts. It is better to know ahead of time your security weakness so that you can fix them then to wait until after a security breach occurs.