I have an ISO Linux FOSS operating system customized media. When I use it, it asks me to log in, but I don’t know that password. What way can I find out the password?
Many customized Puppy and/or OpenSuse distributions use tux/linux for user/password.
What is "ISO Linux FOSS" and how did you customize the media?
ISO is an image format which usually means it was some sort of distribution and FOSS just stands for Free and Open Source Software.
The login and password is either found on the Distributions website (e.g. in a Wiki or Documentation) or you had to specify it during the installation.