Questions regarding password-based authentication and password management
30
votes
2answers
9k 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 ...
21
votes
3answers
6k views
Disable a user's login without disabling the account
Let's say I create a user named "bogus" using the adduser command. How can I make sure this user will NOT be a viable login option, without disabling the account. In short, I want the account to be ...
15
votes
10answers
853 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.
15
votes
5answers
6k 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. ...
13
votes
2answers
678 views
SSH ignores characters after correct password string?
Remote machine 10.10.10.1 has password "asdFGH12" for user named "user". I'm able to log in even if I type in password "asdFGH12dasdkjlkjasdus" or any other characters after the "asdFGH12" string.
$ ...
11
votes
6answers
1k views
Is there a root password on OS X and Ubuntu?
When you setup a new Ubuntu or OS X installation a user is generally created for you. On OS X it is whatever username you pick. On Ubuntu (the server version) usually the ubuntu user is created.
The ...
11
votes
3answers
280 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 ...
11
votes
3answers
513 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 ...
9
votes
4answers
8k views
How to check password with Linux?
I want to check, from the linux command line, if a given cleartext password is the same of a crypted password on a /etc/shadow
(I need this to authenticate web users. I'm running an embedded linux.)
...
8
votes
2answers
504 views
How do I log into my Linux laptop if I have forgotten both the login and password?
How do I log into my Linux laptop if I have forgotten both the username and password?
8
votes
1answer
149 views
Does ssh-agent store my passphrase?
Is it possible to determine the passphrases of private keys added to ssh-agent?
I'm thinking along the lines of someone with root privileges trying to find out my passphrase after I have added the ...
8
votes
4answers
2k views
Command-line password manager that uses SSH key to authenticate
I'm looking for a command-line password manager, much like pwsafe, but one that features SSH key authentication. That is, I'd like to be able to add my SSH key to the authentication when opening the ...
7
votes
3answers
5k 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 ...
7
votes
2answers
1k 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 ...
7
votes
1answer
1k 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 ...
7
votes
1answer
637 views
In /etc/group what is the meaning of the second field?
A sample /etc/group file contains the following entries:
root:*:0:
adm:!:4:logcheck
antoine:x:1000:
The man pages I've read (Debian & OSX) says the second field is to store a group password. ...
7
votes
3answers
2k views
Simplest way to password protect a directory and its contents without having to create new files?
I would like to password protect or encrypt a directory and all the files within it (for the whole directory tree below it). I do not want to bother the whole home directory, I want a specific ...
7
votes
3answers
1k 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 ...
6
votes
4answers
4k views
can we know the password for the other users if we have root access?
If a person has root access to a particular RHEL machine, will they be able to retrieve the password of the other users?
6
votes
5answers
4k 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?
6
votes
4answers
688 views
Is it possible to change password database file(/etc/passwd) in linux?
Is it possible to change password database file(/etc/passwd) to some other file. How does this authentication mechanism work internally ?
Does it depend on pam ?
6
votes
1answer
144 views
Why do we need an expiration period?
Why is there a gap between the expiration of an account and its complete deactivation, when one can no longer log in or change his password when it became expired?
6
votes
2answers
2k views
Why is sudo telling me my password is wrong?
I recently installed OpenBSD 4.9 in my computer, so I could learn a little bit about Unix-like operating systems. I added a new user to the system called bruno. Ok. When I use the 'sudo' command, it ...
6
votes
4answers
694 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 ...
5
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 ...
5
votes
5answers
8k views
Program for decrypt linux shadow file
Is there any program or script available for decrypt Linux shadow file ?
5
votes
2answers
10k views
How do you change the root password on Debian?
I want to change the password I assigned to root on my Debian webserver to something longer and more secure.
Bit of an obvious newbie question, but how do I do that? I haven’t forgotten/lost the ...
5
votes
3answers
1k 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.
5
votes
3answers
258 views
Remote shell script Enter passphrase for
How can I run a script to log into a remote server and execute a remote ssh command without entering in my passphrase?
For example:
When I log onto a remote server and execute the git pull command I ...
5
votes
1answer
289 views
Linux Root Recovery
On Ubuntu 10.10 I can login as root without the root password by replacing ro quiet splash with rw init=/bin/bash. How can I secure my machine and disable this backdoor?
5
votes
1answer
1k views
export HTTP_PROXY and special characters in passwd
Suppose for the sake of argument my password below is abc123@
I need to authenticate my linux machine through a corporate proxy to get patches and updates... normally I'd use this:
export ...
5
votes
3answers
1k views
Getting the password expire time
Let me preface this with: I do NOT have root access available.
I recently got locked out of my account because I did not know the password expiration was getting close, then elapsed. I want to add a ...
5
votes
2answers
271 views
Pipe Password to Application When Asked
The following should be done in a bash script:
curl --digest --user schmijos https://bitbucket.org/u/p/get/tip.zip -o tip.zip
How can I automatically submit a password to curl when it asks for it? ...
5
votes
2answers
436 views
How to check for empty passwords?
Looking at all the ssh-login attempts by script-kiddies I assume that there are messed up systems connected to the internet that have password-less accounts set up.
But how to check a Linux/Unix ...
5
votes
1answer
213 views
Automated ssh login with passphrase?
Logging onto a machine over ssh typically requires a password to be entered before access is granted. Alternatively, a key/certificate (without a passphrase) can be installed onto the remote machine ...
5
votes
3answers
2k views
Safe way to pass password for >1 programs in bash
I'm writing a bash script, and need to ask user for his password and pass it to openssl. Whilst openssl can read the password itself, I need for two runs of the program and don't want to ask the user ...
5
votes
4answers
1k views
automatic passwordless ssh at login/restart
I want to have passwordless ssh to persist even after after I restart or logoff and then login. Somehow I have to run ssh-agent and use command ssh-add at login. I read here to add following lines to ...
5
votes
1answer
1k 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 ...
5
votes
2answers
975 views
Can KWallet manage my ssh passwords?
I need a way to store some SSH passwords. Note that these are login passwords which I need to pass to ssh; key authentication is unfortunately not an option. I'd like to be able to have KWallet fill ...
5
votes
1answer
142 views
epiphany plugin for password storage
I am looking for a keepass plugin for epiphany. Something like PassIFox for Firefox: PassIFox "behaves" like a new password storage for firefox - and redirects all queries (fetch/store etc..) to ...
4
votes
2answers
657 views
Reading passwords without showing on screen in Bash Scripts
How to read passwords in bash scripts in a way like tools which are not showing it on terminal ?
(Changing font to black on black might be tricky by easy to copy&paste - so it's not solution)
4
votes
2answers
539 views
Second field in /etc/shadow
If the second field of the /etc/shadow file is set to !!, does it mean that the account is disabled? Or does it mean that the account is active with no password assigned?
4
votes
2answers
6k views
How to get back sudo on Ubuntu?
I have done this:
sudo chown -R myname /usr/
and now I can't use the sudo command because of this error:
sudo: must be setuid root
And as I read this means that the owner of this file ...
4
votes
2answers
67 views
Determining the Password Status of a User
I have a debian box that I connect to via SSH. I have removed the password from the users root, and my personal account using the instructions here, and set up a public/private key pair so I can log ...
4
votes
1answer
527 views
Not able to set password in ArchLinux
I logged in as root and created a new account:
# useradd -d /home/onie -m onie
# su onie
Now I try to set the password for onie myself using the passwd command, but it's asking for my current ...
4
votes
3answers
299 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 ...
4
votes
1answer
193 views
Encrypt word X to /etc/shadow encryption
I've changed my password to X and the shadow file has changed to:
ahmad:$1$oYINSKjP$eCkCtJV/2dXerAD57WQPj/:15425:0:99999:7:::
I see the encrypted X as $1$oYINSKjP$eCkCtJV/2dXerAD57WQPj/. How can I ...
4
votes
3answers
1k views
How to create SHA512 password hashes on command line
In Linux I can create a SHA1 password hash using sha1pass mypassword. Is there a similar command line tool which lets me create sha512 hashes? Same question for Bcrypt and PBKDF2.
4
votes
2answers
223 views
Password protecting a system file? (e.g. /etc/resolv.conf)
I am trying to parental control myself by restricting web access via OpenDNS. The OpenDNS account password will be handed to someone trustworthy. Now, I want to put some restriction on the ...
4
votes
3answers
1k views
scp: localhost password not accepted
I'm attempting to copy a public key to a remote server. I'm logged in locally as [localname] and the key resides locally at ~/.ssh/. I'm also ssh'd into [remote.com] as [remotename], and attempting to ...
