Questions tagged [shadow]
99 questions
165
votes
10 answers
Manually generate password for /etc/shadow
I need to manually edit /etc/shadow to change the root password inside of a virtual machine image.
Is there a command-line tool that takes a password and generates an /etc/shadow compatible password hash on standard out?
Lorin Hochstein
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86
votes
3 answers
What is the 6th character of the password hash on Linux, and why is it often a slash?
On Linux, what is the sixth character of the password hash stored in /etc/shadow?
On my puppy style linux box, if I try to generate 100 random passwords using shuf and /dev/urandom, then the sixth character is / about half the time.
My question is…
insecure
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63
votes
2 answers
Difference between ! vs !! vs * in /etc/shadow
The second field in the Linux /etc/shadow file represents a password. However, what we have seen is that:
Some of the password fields may have a single exclamation
:!:.....
Some of the password fields may have a double exclamation…
JavaTec
- 797
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37
votes
3 answers
When did Unix stop storing passwords in clear text?
When did Unix move away from storing clear text passwords in passwd? Also, when was the shadow file introduced?
ZDOSA
- 487
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35
votes
2 answers
/etc/shadow : how to generate $6$ 's encrypted password?
In /etc/shadow file there are encrypted password.
Encrypted password is no longer crypt(3) or md5 "type 1" format. (according to this previous answer)
Now I have a
$6$somesalt$someveryverylongencryptedpasswd
as entry.
I can no longer use
openssl…
Archemar
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13
votes
2 answers
Disable password on linux user with command
Based on /etc/shadow(5) documentation on the second (password) field:
encrypted password
If the password field contains some string that is not a valid result
of crypt(3), for instance ! or *, the user will not be able to use a
unix password to log…
trikelef
- 381
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10
votes
1 answer
The format of encrypted password in `/etc/shadow`
I see a hashed passphrase like the following in /etc/shadow. I don't quite understand its format.
$y$j9T$F5Jx5fExrKuPp53xLKQ..1$X3DX6M94c7o.9agCG9G317fhZg9SqC.5i5rd.RhAtQ7
It is made of four parts as shown below. According to crypt(5), y means…
user15502206
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8
votes
1 answer
why have programs like su access to /etc/shadow
Normally only root can access /etc/shadow. But programs like su and sudo can check passwords without running as root. So the question is: Why can these programs access /etc/shadow without privileges? I tried to access it without privileges via…
Kritzefitz
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8
votes
4 answers
What's the meaning of NP and UP in the password field of the shadow file
I found some entries in a shadow file whose meaning I don't understand.
user:UP:::::::
user1:NP:::::::
What does UP and NP mean? In addition to those 2, the same shadow file has the normal hashed entry and the LK that indicates a locked account.…
Ayrx
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8
votes
1 answer
Is it normal to have a file called "shadow-" in the /etc directory?
I am noticing a lot of weird files appearing in my router and on my various filesystems. Files in weird places or files that have to do with security with a - sign after them.
If I do ls -l /etc/shadow*, this is what I see.
-rw-r----- 1 root shadow…
PROXY NINJA
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8
votes
2 answers
SHA512 salted hash from mkpasswd doesn't match an online version
I'm puzzled by the hash (ASCII) code stored under Linux (Ubuntu) /etc/shadow.
Taking a hypothetical case, let password be 'test', salt be 'Zem197T4'.
By running following command,
$ mkpasswd -m SHA-512 test Zem197T4
A long series of ASCII…
A. Au
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8
votes
2 answers
Is it possible to change passwords temporarily?
I have a Linux system with several users. I don't know their passwords, nor do I want to know them.
I have to do a batch copy of some of their directories over SSH, with their account and password.
My idea was to make a backup of /etc/shadow, then…
user79264
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8
votes
3 answers
Root and my password are the same
If I cat /etc/shadow I can get the encrypted passwords of root and my user.
These passwords are the same (I know, bad security) for each account, but in /etc/shadow they show up as being different encrypted strings.
Why? Are different algorithms…
user75027
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7
votes
1 answer
How to know if password in /etc/shadow is hashed with SHA or MD?
I want to know my /etc/shadow password hash if its SHA or MD or something else. From what I read, it is related to the $ sign, but I don't have any dollar signs.
Im using Ubuntu 16
Example:
user:0.7QYSH8yshtus8d:18233:0:99999:7:::
Batchen Regev
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7
votes
2 answers
/etc/shadow and /etc/passwd format compatibility
Are formats of files /etc/shadow and /etc/passwd same on all unix and unix-like systems same or are there significant differences?
I mean syntax of files, not file location or name
rkosegi
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