[SOLVED] Need to know how passwd command work's at the backend.

lohin · 01-02-2020, 09:13 AM

Hello Guys,

I am new to Linux and was thinking,

How come the normal user can change his/her own password using passwd command, where as the permission of /etc/passwd file is 644?

Could you please assist me in understanding on how the things work at the backend when trying to perform above.

Thank you for your support

sevendogsbsd · 01-02-2020, 09:16 AM

/etc/passwd does not contain passwords , only info about the user accounts. Passwords are stored in /etc/shadow which is readable only by the root user. The passwords are hashed and are not retrievable via the file. The strength of the hash is distro dependent.

pan64 · 01-02-2020, 09:34 AM

the command passwd itself is setuid, that means it will run as the user of the owner of the /usr/bin/passwd file (which is root), not as the current user. And (obviously) root has right to do the job.

sevendogsbsd · 01-02-2020, 09:41 AM

Thanks pan64 - that was the part I was missing. I thought that was how it worked but wasn't sure.