Questions regarding password-based authentication and password management

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6
votes
5answers
10k views

Can I change root password by sudo, without su?

I can sudo, but I don't have the root password so I can't su root. Using sudo, can I change the root password?
7
votes
3answers
2k views

Why does my sudo ask for password only once but evaluate thrice?

$ sudo some_command Password: Sorry, try again. Sorry, try again. Sorry, try again. sudo: 3 incorrect password attempts $ This is what my shell prints when I enter a wrong password to a sudoed ...
8
votes
2answers
4k views

Forcing sudo to prompt for a password

If I do the following: sudo su - //enter password exit exit //login again straight away sudo su - The second invocation of sudo does not request a password because even though I have logged out ...
2
votes
2answers
2k views

How to get hashed password in /etc/shadow using getpwnam()?

Apparently there is a function (getpwnam) that given a username, will return the appropriate entry in /etc/passwd with the other details for that user (shell, uid, gid, etc.). However, I have no idea ...
9
votes
1answer
5k views

What methods are used to encrypt passwords in /etc/passwd and /etc/shadow?

A careful examination of the /etc/passwd and /etc/shadow files reveal that the passwords stored are hashed using some form of hashing function. A quick Google search reveals that by default, the ...
10
votes
3answers
3k views

How can I make a user able to log in with ssh keys but not with a password?

I would like to create a user and have no password. As in you cant log in with a password. I want to add keys to its authorized_keys by using root. This is for my automated backup system.
3
votes
1answer
741 views

Change default for Nautilus (file_manager) from “Forget password immediately”?

When opening a tab which needs to mount a Samba share, Nautilus 2.30.1 displays a window: Password required for share xxx on localhost Password: [ ] (*) Forget password immediately ( ) ...
6
votes
1answer
2k views

GNOME-keyring KWallet integration?

I use some GNOME apps, and some KDE apps, so some of them use G-keyring and some KWallet... What I would like to have is a single place for managing passwords. Is there a way to integrate G-keyring ...
7
votes
7answers
1k views

Is there a way to store Firefox passwords in a local encrypted database in Linux?

I want Firefox to "remember" my passwords so I don't have to type them in; unfortunately, the built-in password manager stores them in plain text, which is too high a security risk. I'd like to find a ...
14
votes
4answers
455 views

What specific vulnerabilities am I creating by disabling the sudo password?

Here are some instructions on how to disable your sudo password. These carry the following warning If you disable the sudo password for your account, you will seriously compromise the security of ...
7
votes
5answers
21k views

Program for decrypt linux shadow file

Is there any program or script available for decrypt Linux shadow file ?
1
vote
1answer
1k views

How to reset Linux root and grub passwords?

If we forget our Linux root password, we can change it by changing grub's boot options. But in this case, we also set a grub password and forgot both passwords. How can we recover both?
4
votes
3answers
252 views

Randomise or shred memory of an application

Is it possible to randomise or shred memory of a particular application just after its life ends, or better, whenever it deallocates some memory? A command-line utility like this would be perfect: ...
47
votes
2answers
11k views

Why is there a big delay after entering a wrong password?

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 ...
12
votes
3answers
774 views

How can I tell *which* application is asking for access to gnome-keyring/Seahorse?

Whenever I log in on Ubuntu Lucid Lynx 10.04 I get a Seahorse/gnome-keyring prompt telling me an application wants to access my keyring. It isn't the network manager, because if I cancel the request ...
5
votes
2answers
472 views

Why is 8 numbers considered a “strong” password?

Just curious as to why 8 numbers are accepted as a password in linux (CentOS if it matters) and not 8 characters on a non-dictionary word. It's 10 vs 26 per digit after all. (52 counting CaSe ...
7
votes
4answers
1k views

How to set up two-factor authentication with OTP on FreeBSD?

I have a FreeBSD hosted server that I like to be able to get to from anywhere. Normally I use SSH publickey to log in, or if I don't have my SSH private key available then I might use regular password ...
2
votes
8answers
3k views

How to give a normal user permission to change root password

Please do not ask why, but is it possible to do it? p/s: I know it's not a good thing, let's just say someone from the top management who is computer illiterate want some sort of control over the ...
4
votes
3answers
394 views

Something like pwgen-win for linux?

Is there some kind of pwd generator for Linux that has a nice GUI and options like this one for Windows? I know that there is pwgen, but as far as I know it does not support mouse/keyboard entropy and ...
8
votes
3answers
11k views

passwordless ssh for another username?

I want to do a passwordless ssh connection for a subversion project. Right now I'm using ssh+svn, and it's a little annoying, because I have to type the password any time I want to transact with the ...
18
votes
11answers
4k views

How to create strong passwords in Linux?

I wonder how I can create strong passwords on Linux (for both normal and admin users) and if there are specific programs to do that.
20
votes
6answers
13k views

How do you create a user with no password?

In os X it's possible to have users without passwords. If you inspect them with dscl their password show up as *. This is used for system users such as users for databases like mysql, pgsql etc. ...