Router Security Shodan Query My Router Website by     
Michael Horowitz 
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I spoke about Router Security at the O'Reilly Security Conference in New York City on Nov. 1, 2017. See a PDF of the slides


Websites can easily learn your public IP address. It's obviously necessary for the site to know this, since it needs to send you a web page. This page uses PHP to learn your public IP address, which is shown below.

All devices in a home share one public ip address, and its assigned to the router.
name is aka Reverse DNS

Your public IP address:
Your public computer name:

Your Customized Shodan Query:


A Shodan query of a public IP address is only valid on a computer behind the router you want to test. To run this query for your home, from your office, you would first need to learn your home IP address.

This query is not valid from a computer that is connected to a VPN. In this case, the query is for the VPN server rather than your router.

It is also not valid from a computer connected to TOR. In this case, it would be testing the TOR exit node computer rather than your router.

Finally, your current IP address may not have been your IP address yesterday or last week or last month. Most consumer Internet connections have dyanmic (i.e. variable) IP addresses. When it changes, is up to your Internet Service Provider. Most of the time, it matters not. But, here it matters. Shodan may have last checked the IP address you are currently using a week or two ago (look for the "Last Update" field on the left side). At the time Shodan last checked, you may not have been using your current IP address. So, this could all be a waste of time.

Shodan does not query every IP address every day. You need to check the Last update date/time. The format is ugly and not documented, at least not in the UI. An example is below.
Last Update 2017-03-08T03:21:44.262872
This is March 8, 2017, not August 3, 2017. Everything after the T is a timestamp.

Shodan does not query every IP address. You may well get a Not Found error. opendns google dns
not found pix/shodan.notfound.jpg
vpn server pix/Shodan.VPNserver.gif ports 80, 443, 500, 1723 last two are for VPN usage
One port you dont want to find open is 7547. Link to my blog on this. pix/Shodan.port.7547.gif
This page was last updated: March 22, 2017 1PM CT     
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