Hello all,
Did buy used router (Linksys) and it came with OpenWrt already. I just did reset to defaults, and updated from web gui to newest version of OpenWRT. Now I am maybe too sceptical, but can there be some stuff left to spy on me from previous user? How can I be sure that router is clean?
When you reset openwrt in general, it will reset everything to the default image state in rom. However, if the image on that system was custom built, whatever was included and configured in that image would be your default state.
If you are concerned, download the latest stable release build from the openwrt downloads page and flash it to the router - this way you know you are running an official release that has not been altered by a 3rd party.
And when flashing the stable release, make sure that you do not "keep settings" in sysupgrade.