An unknown android device is connecting to my wireless router even after changing the wifi key several times. How is this possible? My router admin page doesn't have a password set. Even though how is it possible to access the admin page before connecting to the wifi.
closed as off-topic by Xander, Steffen Ullrich, Rory Alsop♦ Jun 19 '17 at 22:15
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question does not appear to be about Information security within the scope defined in the help center." – Rory Alsop
Yet another question asking for help that got unfairly downvoted by an anonymous coward who didn't bother to help. Upvoted and FTFY.
Anyway, now for the answer. You mentioned your router admin page isn't login protected. Rookie mistake, right off the bat. If the owner of the unknown device knows the manufacturer and model of your router, it becomes trivial to look up the config instructions for the router, navigate to the admin page, and change various settings, including the router key.
Intuitively, there should be a chicken-and-egg problem preventing access even if you have a setup like that: the unknown device doesn't have the router access info, so it has no way of getting on the network to access the admin page. However, this becomes a problem if your router allows open access through some misconfiguration (Veroxi's comment provides a good example).
I have no idea if your router supports MAC-address banning - if it does, you could see if you can find access information, find the MAC address of the offending device, and ban it.
Finally, as Daniel E. said, use a good encryption and authentication scheme. The modern standard is WPA2. In particular, stay away from WEP. Most modern routers will use WPA or WPA2 by default if you setup the router to require authentication.
Ensure that you have wps turned off.
Wps is like a "secondary password" in form of a pin, that allow in many cases WPA passphrase crack.
@Rahul Please ensure that you have wps turned off under your advanced Wifi config in routers webAdmin pannel.