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54 votes

Authentication is required to create a color profile

I had the same problem and found a different work-around here: https://github.com/TurboVNC/turbovnc/issues/47#issuecomment-412005377 This variant is claimed to work independent of authentication ...
Nemo's user avatar
  • 2,083
46 votes
Accepted

PasswordAuthentication no, but I can still login by password

Ubuntu/Debian distributions have the non-standard entry Include /etc/ssh/sshd_config.d/*.conf at the beginning of the distribution sshd_config. The purpose of this is to allow users to customize ...
user4556274's user avatar
  • 9,015
31 votes

Add a user without password but with SSH and public key

On Ubuntu you can add the user with: adduser --disabled-password <username> Then create .ssh/authorized_keys file in their home directory with their public key.
Mitar's user avatar
  • 646
23 votes

How to sign into an open Wireless Network?

If redirect page does not load, and reconnecting does not fix the issue, then the easiest next step is to address the router directly. Try 192.168.1.1. That is the most common default address, and ...
Matt's user avatar
  • 231
23 votes
Accepted

Unable to login with SSH-RSA key

You will get this behaviour if the file mode of the user's home directory on the destination host is not set correctly. It's not just the mode of the .ssh directory that has to be correctly set! ssh ...
woolfie's user avatar
  • 346
22 votes

How does Linux identify users?

If you force there to exist multiple users with the same username, then there will be multiple entries in /etc/{shadow,passwd} with the same name: $ cat /etc/passwd ... a:x:1001:1002::/home/a:/bin/...
Andy Dalton's user avatar
21 votes
Accepted

Authentication is required to create a color profile

EDIT: Please use the upvoted answer and not this one. OLD ANSWER: I found this bug and some workarounds here: https://bugzilla.redhat.com/show_bug.cgi?id=1149893 More specific you have to place a ....
koleygr's user avatar
  • 345
20 votes

Meaning of “Connection closed by xxx [preauth]” in sshd logs

In my case, these messages appeared in /var/log/secure when I was experiencing Host key verification failed. errors on the ssh client side. This is one of the cases that would result in a connection ...
pcronin's user avatar
  • 332
20 votes

What program in Linux computes the hash of the input password when you log in?

No specific binary does the hashing; it's done by a library call crypt(3). So, in theory, any program (even a perl script) can generate the hash. e.g. perl -e 'print crypt("hello","\$...
Stephen Harris's user avatar
14 votes
Accepted

/var/log/auth.log stops recording authentication errors

Have you restarted rsyslog or kill -HUPped it after recreating the file? You probably should. In POSIX-compliant systems, deleting a file while some other process is using it will make the file ...
telcoM's user avatar
  • 97.2k
13 votes

Does ssh send the password over the network?

Yes. The password is sent over the encrypted connection, but it's in plaintext to the remote server. The usual way to authenticate is for the server to calculate a hash of the password and to ...
ilkkachu's user avatar
  • 139k
12 votes
Accepted

Allow passwordless root login on the serial console

After some experimenting, I've got something that works: Run systemctl edit [email protected], and add the following: [Service] ExecStart= ExecStart=-/sbin/agetty -o '-p -- \\u' --keep-baud ...
larsks's user avatar
  • 34.9k
11 votes
Accepted

How does Linux identify users?

In Unix, users are identified by their ID (uid), which must be unique (in the scope of the local system). So even if it were possible to create 2 different users with the same name (adduser on my ...
Lollen Jumplan's user avatar
11 votes

system policy prevents control of network connections

Try with a pkla (PolicyKit Local Authority) file: $ sudo ls -la /etc/polkit-1/localauthority/50-local.d total 16 drwxr-xr-x 2 root root 4096 Dec 28 20:08 . drwx------ 7 root root 4096 Aug 1 2017 .. ...
jsiwrk's user avatar
  • 111
10 votes

Meaning of “Connection closed by xxx [preauth]” in sshd logs

I had the same problem, I solved it like this: On the ssh server, I uncommented, and put at yes the following values in /etc/ssh/sshd_config RSAAuthentication yes PubkeyAuthentication yes And ...
matt's user avatar
  • 229
10 votes

Meaning of “Connection closed by xxx [preauth]” in sshd logs

I had a very similar problem to yours (though I was using public key). It turns out my problem, and possibly yours, was caused because my home directory was a NFS mount, and selinux (on CentOS 7) was ...
Simon's user avatar
  • 101
10 votes
Accepted

How to retrieve ssh password with a working ssh key

No, there is no relation between an account password and the ssh key. You can logon to an account with ssh with a key even if it has no password. For the updated question, yes, type: su YOURUSERNAME ...
laktak's user avatar
  • 5,984
10 votes

PasswordAuthentication no, but I can still login by password

Login by password could be performed not only with PasswordAuthentication. Actually, it is the "dedicated simple" method of authentication, and there is a generic method which, amongst ...
Nikita Kipriyanov's user avatar
9 votes

Allow user1 to "su - user2" without password

This might be the possible best way. su is not meant to do that -- sudo is. Open /etc/sudoers.d/custom and write the following: user-a ALL=(user-b:user-b) NOPASSWD:ALL This means: whenever user-a ...
champion-runner's user avatar
9 votes

How to sign into an open Wireless Network?

After none of the above answers got me into "Wifi on ICE" on a German train, I ran into https://gist.github.com/martinvirtel/5d35ff7a82fd4c26d502e37682a6d101. Type route -n to see the IP ...
cayhorstmann's user avatar
9 votes

How to stop sudo PAM messages in auth.log for a specific user?

Based on Toby's answer, I found a way to configure this in a slightly different way on Debian/Ubuntu. For context, see: https://manpages.debian.org/stretch/libpam-runtime/pam-auth-update.8.en.html ...
thom_nic's user avatar
  • 547
9 votes

mounting a CIFS filesystem directly or via fstab

It's good practice to avoid putting passwords directly in /etc/fstab (which is normally world-readable). Instead, put them into a file, and reference the file like: //w.x.y.z/Home$ /mnt/dir cifs ...
Toby Speight's user avatar
  • 8,676
9 votes
Accepted

Does ssh send the password over the network?

If you're using password authentication, then SSH sends the password over the network. The connection is encrypted, so eavesdroppers can't see the password. The connection is authenticated, provided ...
Gilles 'SO- stop being evil''s user avatar
9 votes
Accepted

ssh-copy-id succeeded, but still prompt password input

Thanks to https://unix.stackexchange.com/a/55481/106419, which told me how to debug ssh. To enable ssh debug to see what happen systemctl stop sshd /usr/sbin/sshd -d -p 22 I found: Authentication ...
Mithril's user avatar
  • 525
8 votes

How can I CTRL^C out of a password prompt?

You can CTRL-D su's prompt. This shortcut signals an end-of-file on the console, quitting the prompt; the console will display Authentication error, which is expectable.
joH1's user avatar
  • 908
8 votes
Accepted

How to disable authentication requirement for VirtualBox's shared folder?

I had the same problem, and found the solution here: Note: Access to auto-mounted shared folders is only granted to the user group vboxsf, which is created by the VirtualBox Guest Additions ...
Joe's user avatar
  • 196
8 votes

What program in Linux computes the hash of the input password when you log in?

when we input the credentials in the login prompt, the hash of the password is computed and then that hash is compared with the hash stored somewhere, and if I am not mistaken that "somewhere&...
Gilles 'SO- stop being evil''s user avatar
7 votes

Meaning of “Connection closed by xxx [preauth]” in sshd logs

Another source of these kind of messages is ssh-keyscan. It just grabs server host keys and disconnects without doing any authentication.
x-yuri's user avatar
  • 3,373
7 votes

Disabling ssh password authentication does not work on my debian VPS

You should double check if your /etc/ssh/sshd_config file has any Include directive. If so, follow the included files and check if PasswordAuthentication is correctly set. In my case: Fedora33, my ...
Catalin Crenguta's user avatar
7 votes
Accepted

mounting a CIFS filesystem directly or via fstab

When you type the mount command, the part password='C' is first handled by the shell and becomes password=C before it gets to the mount command. This is not done with fstab entries, so you must remove ...
meuh's user avatar
  • 51.5k

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