Im recently working on a clients box, and SSH into the box with root credentials work but when i try to su or sudo to root user it states incorrect password. I tried changed the root password and know im typing it correctly.
Thanks for help
sudo and su have different configuration files.
For sudo to work properly, the non-root user you are logging in should be either explicitly (I mean by user name) or implicitly (either in a UNIX group or in a defined set of users) permitted to run
For su, check the /etc/pam.d/su file to see if it is configured to prevent from being run.
And neither of these prevent you from logging directly into troot account from ssh, provided sshd_config file is permitting this login, which in your case, is true.