Router Security Test Your Router Website by     
Michael Horowitz 
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DNS Server Tests

A very common thing that bad guys do when they attack a router is change the DNS servers. There are many reasons for this, one is that almost no one will detect the change. A great defense is knowing what the DNS servers in a router should be.

On a totally different plane, is Steve Gibson's Router Crash Test. While working a DNS spoofability test, Gibson accidentally discovered that he crashed some routers just by sending them legit DNS requests. This is a bit dated (Gibson has no creation dates on the pages of his site) but it takes only a few seconds to verify that your router does not fall prey to this attack. At the bottom of the page look for a gray "Initiate Router Crash Test" button.

Firewall Testers

TCP Ports to Test

Note that while connected to a VPN, these tests test the VPN server, not your router. Same for Tor. This list is extremely incomplete.

UDP Ports to Test

Note that while connected to a VPN, these tests test the VPN server, not your router. Same for Tor. This list is extremely incomplete.

TCP/IP Port Information

LAN side port testing

TELNET: Individual LAN side ports can be tested from a computer on the LAN with Telnet. Windows 7 and 8.1 users will have to first install the Telnet client using: Control Panel -> Programs and Features -> click on "Turn Windows features on or off" in the left side column -> Turn on the checkbox for Telnet Client -> Click OK. On OS X ....

To use telnet on Windows, open a Command Prompt window, type "telnet ipaddress portnumber". For example: "telnet 80". There needs to be a space on both sides of the IP address. If the port is closed, Windows will complain that it "could not open connection to the host on port 80: connect failed". If the port is open, the responses vary, you may just see a blank screen. You can also telnet to a computer by name, such as "telnet 8080"

ID Serve: ID Serve is a small, portable, Internet Server Identification Utility for Windows, created by Steve Gibson. It was written in 2003 and has not been updated since. The initial screen explains its purpose, the Server Query tab is where it does its work. You can query a computer by name ( or by IP address. It defaults to port 80, but you can force a different port by adding a colon and the port number after the computer name or IP address (no spaces). If data comes back from the query, ID Serve displays it all. This data may identify the server software. If data does not come back, the message, in my experience, will either be "The port is closed, so our connection attempt was refused" or "No response was received from the machine and port at that IP. The machine may be offline or the connection port may be stealthed". ID Serve is limited to TCP (no UDP) and does not support HTTPS.

BROWSER: You can also test a port with a web browser. For example, would test TCP port 999 (of course, modify the IP address as necessary for your router). I don't think a browser can test a UDP port, it is limited to TCP.

NMAP: Perhaps the best option is nmap...

HNAP Testing

The Home Network Administration Protocol is a network device management protocol dating back to 2007. There are four problems with HNAP. One, is that it has a long history of buggy implementations. It can also tell bad guys technical details of a router making it easier for them to find an appropriate vulnerability to attack. The fact that a router supports HNAP may not be visible in its administrative interface. Worst of all, HNAP often can not be disabled. Four strikes, you're out.

You can test if a router supports HNAP by typing where is the IP address of your router. Of course, every router has two IP addresses one on the public side and one on the private side. I suggest testing for HNAP on each.

You can learn your public IP address at many websites, such as and For the LAN side of a router, see my Sept. 2013 blog Find the IP address of your home router.

If HNAP is enabled, this test displays basic device information about your router in an XML file. See sample output. If it fails, there will be some type of error about the web page not being able to be displayed, perhaps a 404 Not Found error.

If HNAP is enabled, try to turn it off in the router administrative interface and then test again. You may not be able to turn it off. For more, see the HNAP page.

URLs to try from your LAN

In these examples, represents the LAN side IP address of the router.

As per Scott Helme's 2014 description of his BrightBox router, try the URL below, where is the IP address of your router. A good result returns nothing but an error message. Here is a sample of a bad result.

In December 2016, Pedro Ribeiro reported on flaws in the Netgear WNR2000 router. If you own a Netgear router, it can't hurt to check for information leakage with the URL below. It may leak the device serial number.

UPnP Testers

The online tester below insures that your router does not respond to UPnP requests sent to it over the Internet. As for why UPnP is an issue at all, see my Jan. 2013 blog Check your router now, before Lex Luthor does. UPnP is relatively hard to test for as there are two components to the protocol. Discovering UPnP enabled devices is done with the Simple Service Discovery Protocol (SSDP) which listens on UDP port 1900. The actual communication between devices is done via HTTP on varying ports. SSDP tells clients which port to use for HTTP communication. According to Rapid7, the TCP port number varies by vendor and is often chosen at random. Ugh. Their report notes that some Broadcom, D-Link and TP-Link routers use TCP port 5431, some devices use port 80 and still others use 2869.

Modem Tests

A modem is a computer and it too, can have bugs. Chances are the modem as an IP address such as If nothing else, you should try to access the modem by its IP address so that technical information about your ISP connection is available to you. Also, you want to see what information is available without a password, some modems expose too much. If there is a password, then change it from the default. For better security, a router should be able to block access to the modem by blocking its IP address.

IP Version 6 Tester

I know of no reason for IPv6 to be enabled on a home router. If it is enabled on yours, try to disable it then verify that it's really off.

The only website that I know that tests for the existence of IP version 6 is Click on the "IPv6 only Test" or go directly to It is a good thing if fails to load in your browser.

Android app

According to the company, RouterCheck "is the first consumer tool for protecting your home router ... RouterCheck is like an anti-virus system for your router. It protects your router from hackers..." Its an Android app. I have not tried it.


Honorable mention goes to the Shadowserver Foundation that scans the Internet for all sorts of things that should not be there.
See The scannings will continue until the Internet improves.

This page was last updated: January 12, 2017 7PM CT     
Created: December 5, 2015
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