Password at startup

Hello

to louloudu6919,

he was pressing enter without entering a password, of course access is denied but he does this three times and then as a password he writes a word ... I don't know what it is and then it allows him to change the password and later log into the session ... 

This story doesn't hold up at all. What you're describing is strictly impossible. Your "little brother" is misleading you in one way or another.
Either he has created an administrator session under which he logs in, or he has activated the root user to do whatever he wants on the Mac, on any session. He could have done this while you weren't watching. He can only use a method made possible due to an error of usage on your part.

To protect yourself, check in System Preferences / Accounts ... that there are no unwanted accounts. In the login options, set the Mac to require both, in its login window,
-the username
and
-the password
And not just the password. You can also take this opportunity to change your password and also your username
A bit of reading, although according to you very skilled, you probably know all this by heart..
https://forums.commentcamarche.net/forum/affich-4143450-compte-sous-mac-os-x#3
https://forums.commentcamarche.net/forum/affich-6871575-mot-de-passe-a-l-ouverture#1
https://forums.commentcamarche.net/forum/affich-14948938-deverrouiller-fichier-ou-photo-sur-mac-os-x#4
https://forums.commentcamarche.net/forum/affich-5552951-mise-a-jour#1

For the root user,
check that it is indeed disabled, the method depends on the version of Mac OS in use. Not knowing which version this is, I can only advise you to go to Mac OS help and type
Disabling the root user, in the search area.

Indeed, you give absolutely no indication as to the exact model of the Mac and the exact version of Mac OS in place.... and yet these 2 pieces of information are essential to be able to assist you best.

PS: you can also request in System Preferences / Security, that the Mac requires a password after sleep...

to enark78,

Filevault has absolutely nothing to do with this, and

but it seems to me that if you make several mistakes, it is sufficient to enter the password set with filevault.

is absolutely not true. On the contrary, it is better to be cautious in the event of using Filevault. Forgetting the password will result in an unrecoverable session. Since the entire user's directory is encrypted.

Warning: do not forget your master password. If you enable FileVault and forget your login password and your master password, you will not be able to log into your account and your data will be permanently lost.

Excerpt from this page
http://docs.info.apple.com/article.html?path=Mac/10.6/fr/8736.html

Best regards

--
Sanspseudo - Francis - iMac Intel Mac under OS 10.6 + iMac-G5 under Mac OS 10.5
Always indicate your exact configuration: Mac model and version of Mac OS..

Yes, of course, you can revert to the original state or switch to another option; just go back to the preferences and make the reverse or different modifications.
Before making this change, also make sure to check what your username is.
By default, the name to enter in the dialog window at startup is your "short name", but you can change it in system preferences / accounts / Options / Password.

For example, if your name is Paul Dupont, that’s what you entered when installing the Mac, your short name will be "pauldupont". If you entered Jamel Debouze, that name will become "jameldebouze", and this short name is what to enter by default, along with your password.
But you can change this, and decide that the name to enter is "coucoucémoi" or "jean" etc...
So if you made such a modification in the past, don't forget it or check before making changes.

Also see these messages:
http://www.commentcamarche.net/forum/affich 4143450 compte sous mac os x#3
http://www.commentcamarche.net/forum/affich 5552951 mise a jour#1

Best regards

--
Sanspseudo - Francis
iMac G5 2ghz 2Go - OS 10.5.3

Hello,
The Mac accepts or rejects the password depending on whether it has been typed correctly. It is never due to chance. If the Mac accepted it on the tenth attempt, it means the previous nine attempts were typed incorrectly. There is no other possible explanation. In computing, nothing is due to chance.
Be careful with uppercase/lowercase when entering your password; sometimes the Caps Lock key is on and we don't notice it.

Best regards
--
Sanspseudo - Francis
iMac G5 2ghz 2Go - OS 10.5.3

Hello

@louloudu6919

I don't know how your little brother does it, is he a whiz at computers?
To me, he simply knows the password.

What to do:
First of all, and this applies to all your data, you need to back it up on an external drive or a USB stick; your brother deleted an important file, but if your hard drive crashes, all your data will be lost.

Change your password; a password should not be a word from the dictionary or a name (like that of the dog, cat, etc...) and should contain special characters (periods, commas, numbers, or dollar signs, etc...)

See you later!

Hello,

Then you need to delete them (as well as any copies he might have made) otherwise he will continue his rebellious teenager antics.

Ritchi

Hello,

This takes place in "System Preferences... -> Accounts -> Options"
Choose "Automatic login = disabled"

Ritchi

Hello, I have a problem. On the iMac at home, we have several accounts:
each of my brothers and sisters has their own account (including me) and there is one for my parents.

However, despite the fact that we have passwords, my little brother can get into our accounts...
I've seen roughly how he does it:
he presses enter without entering a password, of course, access is denied, but he does this three times, and then as a password, he writes something... I don't know what it is, and then it allows him to change the password and subsequently log into the account... I don't need to tell you that it annoys me because I have a lot of important documents and he has already deleted (just to bother me) over 10 GB of important files, and when I say important, I mean very important. It's the only copy I had of my band's recording in the studio... We spent three days in the studio making this album, it cost us over 300 euros, and we had saved everything on the iMac, and there you go... He doesn't even realize what he is capable of doing. Anyway, I'm not going to tell you my life story, but I just want to ask you to clarify this for me...
Thank you.

For the question from louloudu6919.

Could it be due to FileVault which, after a certain number of failed login attempts, only asks for the password saved for it? Couldn’t his brother have set up FileVault to create a password that only he knows?
--
The best way to resist temptation is to yield to it -
Experience is the name everyone gives to their mistakes (Oscar Wilde)

_Ritchi_,

we didn't put any sentences, but the CDs are available.. indeed.

Currently, I open my computer without a password. How can I set a password to secure my computer? Thank you.

I have a big problem. I had a power outage and my Mac's hard drive crashed. I replaced it with a new one without any issues, but now it won’t let me install the system on it. It opens the lock with the Alt key, whereas it shouldn't be coded in the first place. I have the original CDs for Mac Snow Leopard 10.6. I try to reinstall by pressing C at startup, but nothing works; it just shows me a folder with a question mark and my iMac keeps spinning without doing anything. I went to the store to have it checked, and they charged me 200 euros to get it working again. I find that outrageous for a machine of this price. I bought Snow Leopard retail again, but I can't get it started. I'm going crazy. If a kind soul could help me, I would be very grateful.

I reiterate my remark/question in case it was overlooked. Isn't it possible that he could use FileVault? He enters the wrong password until he has to enter the FileVault password (which he may have set up). This is just a remark; I'm not very familiar with how FileVault works, but it seems to me that if you make several mistakes, you need to enter the password set with FileVault.
--
The best way to resist temptation is to yield to it -
Experience is the name everyone gives to their errors (Oscar Wilde)

I say it loud and clear: it is IMPOSSIBLE to completely protect your Mac !!
Knowing the American keyboard (QWERTY) and a few system codes, you can do everything...
You just have to start in single user mode, then you become root, if you don’t have a session, you create one, then you type in two little codes (I won't give them to you... right? ;) ) and there you go, you’re an administrator. After that, you change the passwords of others by authenticating and you are the master of the computer! You can even become a super-user.