SELinux – Listing Available Contexts

As you know, I’ve been studying for the RHCE exam. One of the things that I was unsure about with SELinux was how to find all the available contexts. It’s easy to find booleans with the ‘getsebool’ command, but what about a context?

There are TONS of contexts. Today, I found my answer. It’s the ‘seinfo’ command.


October 29, 2012

Posted In: Linux, RHCE Study Notes, SELinux


  • Configure a mail transfer agent (MTA) to accept inbound email from other systems.
  • Configure an MTA to forward (relay) email through a smart host.


Now that postfix is setup, let’s send mail.

Now to check the logs on the mail server and check the message.


Now, let’s set up a mail relay to forward mail to

We need to add an entry called ‘relayhost’ to /etc/postfix/ on Then restart postfix.

Be sure to chkconfig postfix to ensure it will be persistent at boot and you’ll need to make sure that iptables will allow the smtp traffic as well.

October 27, 2012

Posted In: Linux, Postfix, RHCE Study Notes, Sendmail, SMTP