Category Archives: Tips and Tricks

Error :- sudo: effective uid is not 0, is sudo installed setuid root?

We all as a Linux administrator must have come across this error sometime in our lives. [user@host dir]$ sudo bash sudo: effective uid is not 0, is sudo installed setuid root? This happens when sudo does not get the right access permissions. The Solution for this error is giving the following permissions as root user chmod u+s /usr/bin/sudo That Must

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Safest and the least vulnerable way to add a user to the sudoers with full rights

visudo demouser ALL=(ALL) PASSWD:ALL, !/bin/su root, !/bin/su -, !/bin/sudo su -, !/bin/su – root, !/bin/sudo su root, !/bin/su, !/usr/bin/passwd, !/usr/bin/passwd root, !/bin/vi /etc/sudoers, !/usr/bin/sudo vi /etc/sudoers, !/usr/sbin/visudo, !/usr/sbin/sudo visudo, !/bin/chmod 777 /etc/sudoers, !/bin/chmod ugo+rwx /etc/sudoers :wq!  

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How to Send Email from Telnet

We use the “” as an example. Be sure to replace with your own domain. Open your command prompt. Now, connect with telnet using the following command: telnet 25 Some servers also accept helo in place of ehlo. ehlo Type mail mail from: rcpt to:,, To write the message – type data, followed by your subject

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