To send an email directly from Golang you can use the package smtp which implements the Simple Mail Transfer
Protocol (SMTP) as defined in RFC 5321. You also need a mail server, for this tutorial will use the Gmail mail server.
Firewalld is one of the Linux firewall management tool and it is available on the in the Ubuntu's default repositories, therefore it is available to
be installed from these repositories using the apt packaging system.
The switch statement is an easier way to have a sequence of if-else statements. In Golang you don't need to have break at the end of
each case, it breaks implicitly. Also the golang switch statement work on values of any type.
The abstract keyword is used in Java for abstraction. The abstraction is the process of selecting data and displaying only the relevant details to the
object. If helps to reduce the programing complexity and the efort.
Keywords are special words in the programing language which have reserved use in the language.
Keywords may not be used as identifiers in Java; for example you cannot declare a field whose name is a keyword.