Daily tip

I don`t find the firewalld or firewall-cmd tool in Ubuntu!?

These higher level firewall tools are only present in Red hat distros, for Ubuntu or Debian like distribution
please look at ufw documentation.

Daily tip

How can I verify a package (check for modified configuration files or binaries) in a Debian like distribution (Debian, Ubunut, Mint, etc.)?

#dpkg -V <package_name>