How to make sudo commands work over ssh without asking for a password?

Question

I set up a server to accept ssh without passwords, and it works fine for nonprivileged commands.
However, when I try to run sudo commands, I'm still asked for a password:

$ ssh -t test@192.168.1.52  "ls"
Desktop  Documents  Downloads  Music  Pictures  Public  Templates  Videos
Connection to 192.168.1.52 closed.

$ ssh -t test@192.168.1.52  "sudo ls"
[sudo] password for test: 
Desktop  Documents  Downloads  Music  Pictures  Public  Templates  Videos
Connection to 192.168.1.52 closed.
$ 

Googling seems to indicate that ssh -t should let sudo run without asking for a password, but this is not the case above.

Any suggestion what should I do to get sudo commands to work without asking for a password?

OS is CentOS 7.5.

Answer 1

Combining the excellent comments from Torin and Michael,

You must edit sudo configuration to allow commands that you want, optionally including the NOPASSWD: modifier.

Remember that:

• These are privileged files, so you will need elevated credentials (root password, root ssh key, existing sudo rule...) to deploy this.
• You can use the #includedir directive to include a directory of additional sudoers configs, such as /etc/sudoers.d. You can then drop in files such as with a custom software package you deploy.
• You can maintain sudo rules in ldap rather than files. Although you probably have to touch all hosts to update nsswitch.conf. See the sudoers.ldap man page.

ssh -t relates to tty allocation, which is not directly related.

Answer 2

Below command is the proper way for adding user to sudoers:

echo "test ALL = (root) NOPASSWD:ALL" | sudo tee /etc/sudoers.d/test
chmod 0440 /etc/sudoers.d/test

Now you can ssh without disconnected.