I understand the difference between  and , but my question is why do they have both? It seems like an unnecessary complication. Why not just store the encrypted password in the passwd file? Is it somehow more secure separating them? I noticed passwd is accessible to anyone but shadow only to superusers.
120558
What is the purpose of the /etc/shadow file in Linux Operating system?  Also, is it same for SUSE clients? There is one shadow cache file is maintained what is purpose of that?
6464
Any  at all will obviously help when salting and hashing a user's password.  Are there any best practices for how long the salt should be?  I'll be storing the salt in my user table, so I would like the best tradeoff between storage size and security.  Is a random 10 character salt enough? Or do I need something longer?
42777
To stupid people, like me, you would have thought overwriting each bit on a disk would render the data completely unrecoverable.  Why do disk wiping tools have the option for multiple passes, i.e. 3 or 5, even 7 and different methods?  Surely the first pass does the job?  My question - Is it just down to pure paranoia or should I be using multiple passes when wiping disks... and why?
26786
I noticed that I have passwords in the Password/Encryption Keys program  . It appears that anybody who walked up to my computer could go look at all my passwords without needing a master password. Did I do something wrong or is this the default behavior? And if so, why?   and what if i lock my password is it get locked till i log out or for every time when i have 2to see password then i have to unlock keyrings . if then so how i protect my passwords from other . and why it is done so
83485
I'm trying to understand the difference between these two commands: sudo find / -name .DS_Store -delete  and sudo find / -name &quot;.DS_Store&quot; -exec rm {} \;  I noticed that the -exec ... {} method is preferred. Why? Which one is safer/faster/better? I've used both on my Macbook and everything appears to work well.
95297
An encrypted /home directory gets mounted automatically for me when I log in. I have a second internal hard drive that I've formatted and encrypted with Disk Utility. I want it to be automatically mounted when I login, just like my encrypted /home directory is. How do I do this?  There are several very similar questions here, but the answers don't apply to my situation. It might be best to close/merge my question here and edit the second one below, but I think it may have been abandoned (and therefore never to be marked as accepted).   isn't a secure method, it circumvents the encryption.  requires editing fstab, which necessitates entering an additional password at boot. It's not automatic like mounting /home.  is very similar, but does not apply to an encrypted drive. The solution won't work for my needs.  but it's for NTFS drives, mine is ext4.    I can re-format and re-encrypt the second drive if a solution requires this. I've got all the data backed up elsewhere.
60369
I am using a cloned hard drive in attempts to restore some old files.   The cloned drive has 2 users, one with an encrypted home drive, one without. Both are administrators. When I couldn't get into the main user (with the encrypted home directory), I logged in as the 2nd user and changed the password.   It seems that I somehow broke the relationship between the encryption passphrase and the user. I'm pretty sure I have the passphrase. Is there a way to get to the data?
108285
Background info: I am planning on making a filehost with which one can encrypt and upload files. To protect the data against any form of hacking, I'd like not to know the encryption key ($K$) used for a file, so the user will have to asymmetrically encrypt $K$ and send it as well. The reason for this double encryption is that you can still share (individual!) files with other accounts by encrypting $K$ with the public keys of those users, too.  My problem is: How can a user can get a public and private key without the server saving/knowing the private key and without the user having to remember a passphrase of 250 hex characters?  Question: Is there a way to derive a key pair from a password, like PBKDF-2 does for symmetric encryption? Suggestions on rearranging the cryptographic steps in an easier way are welcome, too.  Alternatively: It is also possible to encrypt the private key with a PBKDF-applied password and store it on the server, but I'd like to keep things 'simple'. ;)  Note: At this point I don't care if it requires RSA, ECC or an obscure cryptography scheme.
78799
I find that if I execute something using sudo that then if I execute something else soon after also using sudo, that it does not prompt me for my password, and although this can be inconvenient in some situations, it is a security risk in others, and a hassle to keep on coming back and executing the command to make it prompt your for the password on the next go. So I was wondering if and how I could get it to prompt me every time, or for it to at least only remember my password for a very short amount of time?
63578
I'm trying to understand the difference between the following and what they actually mean :   Known plaintext attack Known ciphertext attack Chosen ciphertext attack Chosen plaintext attack   Any clarification is much appreciated…
33821
I used to use '' and "" (single and double-quotes) interchangeably on the command line, but I recently noticed that '$HOME/some/dir' is not expanded, while "$HOME/some/dir" is. I searched around a little bit and found that "" allows some protection of special characters, while '' allows full protection. So what other characters are protected by '' and not ""?  EDIT: What are practical situations in which these differences might be significant?
67742
I am writing a script to add a large amount of users to a system. Part of this involves setting default passwords for each user. How can I set users' passwords without it prompting me for the password up front?  Unfortunately passwd doesn't seem to take an argument stating the new password to set. I'm using Ubuntu 11.10.
100440
Not that it's a very good idea to change it, but for fun. According to  post, there are still some problems even after changing entries in /etc/passwd, /etc/shadow, and /etc/sudoers. Any suggestions?
8273
I notice a weird (well, according to me) thing about passwords. For example, if I type an incorrect password during login, there will be a few seconds' delay before the system tells me so. When I try to sudo with a wrong password I would also have to wait before the shell says "Sorry, try again".  I wonder why it takes so long to "recognize" an incorrect password? This has been seen on several distributions I use (and even OSX), so I think it's not a distribution specific thing.
83827
One of the most common security best practices these days seems to be . I've never really found a good explanation for that, but I'm assuming it's to minimize the risk of a  malicious or infected script within the webroot from reading the database password.  But, you still have to let WordPress access it, so you need to expand open_basedir to include the directory above the document root. Doesn't that just defeat the entire purpose, and also potentially expose server logs, backups, etc to attackers?  Or is the technique only trying to prevent a situation where wp-config.php would be shown as plain-text to anyone requesting http://example.com/wp-config.php, instead of being parsed by the PHP engine? That seems like a very rare occurance, and it wouldn't outweigh the downsides of exposing logs/backups/etc to HTTP requests.  Maybe it's possible to move it outside the document root in some hosting setups without exposing other files, but not in other setups?    Conclusion:  After a lot of back-and-forth on this issue, two answers have emerged that I think should be considered the authoritative ones. Aaron Adams makes a good case in  wp-config, and chrisguitarguymakes a good . Those are the two answers you should read if you're new to the thread and don't want to read the entire thing. The other answers are either redundant or inaccurate.
124166
I don't understand why is the "tunnel" metaphor used to describe a networking tunnel.  At first I thought the reason was because the data sent is encrypted, and so an eavesdropper will not be able to see the data (he sees the data wrapped in a tunnel!).  But what about the tunneling protocols that do not use encryption, why are they also called a "tunnel"!
48925
It's hard to search for special characters on google, which is why I'm posting this here.  I recently ran (as root) a mv /tmp/folder/* /* when I meant to run mv /tmp/folder/* ./ Big mistake!  Things broke! A lot of files got mixed up and placed into strange places, none of the normal unix commands worked (ls, dir, cat, etc) and once you logged off, you couldn't ssh back in -- it would give you a prompt, but not accept the old passwords.  Running ls /* shows me that it performs ls on every directory in /. If I tried to draw a parallel, then mv should have simply moved (or copied?) the files to every directory in /. Instead, really weird things happened, and I was just curious what exactly was going on.  More info: The files in /tmp/folder had been transferred from a windows machine, and had been named file (#).txt, where (#) is a number up to two digits, with a space between file and the parenthesis. There were ~40 of these text files.