Posts Tagged Under: apache

RHCE – rough notes

page 4:

systemctl –type=service

list all running services:

systemctl –list-units –type=service

list all services, running and not running:

systemctl –list-units –type=service

page 6:

lists the units that this unit depends on:

systemctl list-dependencies UNIT

shows what other services depends on the following unit:
systemctl list-dependencies UNIT –reverse

this forcefully disables a unit, so that it doesn’t start up at boot time or manually started. this
is so to prevent accidentally starting a unit. e.g. don’t accidentally start chronyd if already using ntpd
systemctl mask unit

Opposite of umask:

systemctl umask unit

page 26

the following command is best practice because it is persistent:

nmcli dev dis device

and don’t use (because it isn’t persistent):

nmcli connection down device

page 27:

The following set’s static ip address as well as default gateway address of

nmcli con mod static-eth0 ipv4.addresses “”

note: you can omit the default gateway address.

RHCE – Setting up an Apache Web Server (httpd) on CentOS/RHEL 7

In this series of articles we’re going to set up an Apache Web Server and walkthrough the various Apache configurations and features. To start with this article will cover setting up a basic Apache server with the default out-of-the-box apache configurations.

You can follow along with this Apache Vagrant project. This vagrant project is made up of 2 CentOS7 boxes, one box will act as our webserver (webserver.local – and the other will act as our client (box1.local –

We will also ensure:

  1. firewalld is running and not blocking web server traffic
  2. SELinux is in targeted mode

But for this walkthrough we will initially keep them turned off:

[root@webserver ~]# systemctl stop firewalld
[root@webserver ~]# setenforce Permissive

Installing Apache Software

This is done using yum to install httpd:

[root@webserver ~]# yum install httpd


Take the RHCSA Quiz

This article is part of our RHCSA Study guide (click on the yellow tab on the far left). By the end of this article you should be able to answer the following questions:

What is the command to install Apache web server?

$ yum group install ‘Basic Web Server’

What is the commadn to install a few text based web browsers?

$ yum install elinks lynx

What is the command to start+enable the apache service?

$ systemctl start httpd
$ systemctl enable httpd

What is the command to open up the firewalls?

$ firewall-cmd –add-service=http
$ firewall-cmd –add-service=https
$ systemctl restart firewalld

RHCE – An Walkthrough of the main Apache Configuration file on CentOS/RHEL 7

Nearly all of Apache’s config files are stored under three high-level directories:

[root@webserver httpd]# tree /etc/httpd/conf /etc/httpd/conf.d /etc/httpd/conf.modules.d
├── httpd.conf
└── magic
├── autoindex.conf
├── fcgid.conf
├── manual.conf           # This came from installing the httpd-manual rpm
├── ssl.conf              # This came from installing the mod_ssl rpm
├── userdir.conf
└── welcome.conf
├── 00-base.conf
├── 00-dav.conf
├── 00-lua.conf
├── 00-mpm.conf
├── 00-proxy.conf
├── 00-ssl.conf
├── 00-systemd.conf
├── 01-cgi.conf
└── 10-fcgid.conf

Other rpms can drop files into the *.d directories.

There are quite a few config files that comes with apache, but the main ones are /etc/httpd/conf/httpd.conf and /etc/httpd/conf.d/ssl.conf. Here’s what httpd.conf looks like:

[root@webserver conf]# cat /etc/httpd/conf/httpd.conf
# This is the main Apache HTTP server configuration file.  It contains the
# configuration directives that give the server its instructions.
# See <URL:> for detailed information.
# In particular, see
# <URL:>
# for a discussion of each configuration directive.
# Do NOT simply read the instructions in here without understanding
# what they do.  They're here only as hints or reminders.  If you are unsure
# consult the online docs. You have been warned.
# Configuration and logfile names: If the filenames you specify for many
# of the server's control files begin with "/" (or "drive:/" for Win32), the
# server will use that explicit path.  If the filenames do *not* begin
# with "/", the value of ServerRoot is prepended -- so 'log/access_log'
# with ServerRoot set to '/www' will be interpreted by the
# server as '/www/log/access_log', where as '/log/access_log' will be
# interpreted as '/log/access_log'.
# ServerRoot: The top of the directory tree under which the server's
# configuration, error, and log files are kept.
# Do not add a slash at the end of the directory path.  If you point
# ServerRoot at a non-local disk, be sure to specify a local disk on the
# Mutex directive, if file-based mutexes are used.  If you wish to share the
# same ServerRoot for multiple httpd daemons, you will need to change at
# least PidFile.
ServerRoot "/etc/httpd"
# Listen: Allows you to bind Apache to specific IP addresses and/or
# ports, instead of the default. See also the <VirtualHost>
# directive.
# Change this to Listen on specific IP addresses as shown below to
# prevent Apache from glomming onto all bound IP addresses.
Listen 80
# Dynamic Shared Object (DSO) Support
# To be able to use the functionality of a module which was built as a DSO you
# have to place corresponding `LoadModule' lines at this location so the
# directives contained in it are actually available _before_ they are used.
# Statically compiled modules (those listed by `httpd -l') do not need
# to be loaded here.
# Example:
# LoadModule foo_module modules/
Include conf.modules.d/*.conf
# If you wish httpd to run as a different user or group, you must run
# httpd as root initially and it will switch.
# User/Group: The name (or #number) of the user/group to run httpd as.
# It is usually good practice to create a dedicated user and group for
# running httpd, as with most system services.
User apache
Group apache
# 'Main' server configuration
# The directives in this section set up the values used by the 'main'
# server, which responds to any requests that aren't handled by a
# <VirtualHost> definition.  These values also provide defaults for
# any <VirtualHost> containers you may define later in the file.
# All of these directives may appear inside <VirtualHost> containers,
# in which case these default settings will be overridden for the
# virtual host being defined.
# ServerAdmin: Your address, where problems with the server should be
# e-mailed.  This address appears on some server-generated pages, such
# as error documents.  e.g.
ServerAdmin root@localhost
# ServerName gives the name and port that the server uses to identify itself.
# This can often be determined automatically, but we recommend you specify
# it explicitly to prevent problems during startup.
# If your host doesn't have a registered DNS name, enter its IP address here.
# Deny access to the entirety of your server's filesystem. You must
# explicitly permit access to web content directories in other
# <Directory> blocks below.
<Directory />
    AllowOverride none
    Require all denied
# Note that from this point forward you must specifically allow
# particular features to be enabled - so if something's not working as
# you might expect, make sure that you have specifically enabled it
# below.
# DocumentRoot: The directory out of which you will serve your
# documents. By default, all requests are taken from this directory, but
# symbolic links and aliases may be used to point to other locations.
DocumentRoot "/var/www/html"
# Relax access to content within /var/www.
<Directory "/var/www">
    AllowOverride None
    # Allow open access:
    Require all granted
# Further relax access to the default document root:
<Directory "/var/www/html">
    # Possible values for the Options directive are "None", "All",
    # or any combination of:
    #   Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews
    # Note that "MultiViews" must be named *explicitly* --- "Options All"
    # doesn't give it to you.
    # The Options directive is both complicated and important.  Please see
    # for more information.
    Options Indexes FollowSymLinks
    # AllowOverride controls what directives may be placed in .htaccess files.
    # It can be "All", "None", or any combination of the keywords:
    #   Options FileInfo AuthConfig Limit
    AllowOverride None
    # Controls who can get stuff from this server.
    Require all granted
# DirectoryIndex: sets the file that Apache will serve if a directory
# is requested.
<IfModule dir_module>
    DirectoryIndex index.html
# The following lines prevent .htaccess and .htpasswd files from being
# viewed by Web clients.
<Files ".ht*">
    Require all denied
# ErrorLog: The location of the error log file.
# If you do not specify an ErrorLog directive within a <VirtualHost>
# container, error messages relating to that virtual host will be
# logged here.  If you *do* define an error logfile for a <VirtualHost>
# container, that host's errors will be logged there and not here.
ErrorLog "logs/error_log"
# LogLevel: Control the number of messages logged to the error_log.
# Possible values include: debug, info, notice, warn, error, crit,
# alert, emerg.
LogLevel warn
<IfModule log_config_module>
    # The following directives define some format nicknames for use with
    # a CustomLog directive (see below).
    LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined
    LogFormat "%h %l %u %t \"%r\" %>s %b" common
    <IfModule logio_module>
      # You need to enable mod_logio.c to use %I and %O
      LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %I %O" combinedio
    # The location and format of the access logfile (Common Logfile Format).
    # If you do not define any access logfiles within a <VirtualHost>
    # container, they will be logged here.  Contrariwise, if you *do*
    # define per-<VirtualHost> access logfiles, transactions will be
    # logged therein and *not* in this file.
    #CustomLog "logs/access_log" common
    # If you prefer a logfile with access, agent, and referer information
    # (Combined Logfile Format) you can use the following directive.
    CustomLog "logs/access_log" combined
<IfModule alias_module>
    # Redirect: Allows you to tell clients about documents that used to
    # exist in your server's namespace, but do not anymore. The client
    # will make a new request for the document at its new location.
    # Example:
    # Redirect permanent /foo
    # Alias: Maps web paths into filesystem paths and is used to
    # access content that does not live under the DocumentRoot.
    # Example:
    # Alias /webpath /full/filesystem/path
    # If you include a trailing / on /webpath then the server will
    # require it to be present in the URL.  You will also likely
    # need to provide a <Directory> section to allow access to
    # the filesystem path.
    # ScriptAlias: This controls which directories contain server scripts.
    # ScriptAliases are essentially the same as Aliases, except that
    # documents in the target directory are treated as applications and
    # run by the server when requested rather than as documents sent to the
    # client.  The same rules about trailing "/" apply to ScriptAlias
    # directives as to Alias.
    ScriptAlias /cgi-bin/ "/var/www/cgi-bin/"
# "/var/www/cgi-bin" should be changed to whatever your ScriptAliased
# CGI directory exists, if you have that configured.
<Directory "/var/www/cgi-bin">
    AllowOverride None
    Options None
    Require all granted
<IfModule mime_module>
    # TypesConfig points to the file containing the list of mappings from
    # filename extension to MIME-type.
    TypesConfig /etc/mime.types
    # AddType allows you to add to or override the MIME configuration
    # file specified in TypesConfig for specific file types.
    #AddType application/x-gzip .tgz
    # AddEncoding allows you to have certain browsers uncompress
    # information on the fly. Note: Not all browsers support this.
    #AddEncoding x-compress .Z
    #AddEncoding x-gzip .gz .tgz
    # If the AddEncoding directives above are commented-out, then you
    # probably should define those extensions to indicate media types:
    AddType application/x-compress .Z
    AddType application/x-gzip .gz .tgz
    # AddHandler allows you to map certain file extensions to "handlers":
    # actions unrelated to filetype. These can be either built into the server
    # or added with the Action directive (see below)
    # To use CGI scripts outside of ScriptAliased directories:
    # (You will also need to add "ExecCGI" to the "Options" directive.)
    #AddHandler cgi-script .cgi
    # For type maps (negotiated resources):
    #AddHandler type-map var
    # Filters allow you to process content before it is sent to the client.
    # To parse .shtml files for server-side includes (SSI):
    # (You will also need to add "Includes" to the "Options" directive.)
    AddType text/html .shtml
    AddOutputFilter INCLUDES .shtml
# Specify a default charset for all content served; this enables
# interpretation of all content as UTF-8 by default.  To use the
# default browser choice (ISO-8859-1), or to allow the META tags
# in HTML content to override this choice, comment out this
# directive:
AddDefaultCharset UTF-8
<IfModule mime_magic_module>
    # The mod_mime_magic module allows the server to use various hints from the
    # contents of the file itself to determine its type.  The MIMEMagicFile
    # directive tells the module where the hint definitions are located.
    MIMEMagicFile conf/magic
# Customizable error responses come in three flavors:
# 1) plain text 2) local redirects 3) external redirects
# Some examples:
#ErrorDocument 500 "The server made a boo boo."
#ErrorDocument 404 /missing.html
#ErrorDocument 404 "/cgi-bin/"
#ErrorDocument 402
# EnableMMAP and EnableSendfile: On systems that support it,
# memory-mapping or the sendfile syscall may be used to deliver
# files.  This usually improves server performance, but must
# be turned off when serving from networked-mounted
# filesystems or if support for these functions is otherwise
# broken on your system.
# Defaults if commented: EnableMMAP On, EnableSendfile Off
#EnableMMAP off
EnableSendfile on
# Supplemental configuration
# Load config files in the "/etc/httpd/conf.d" directory, if any.
IncludeOptional conf.d/*.conf

All these settings are defined in the Apache Directives Documentation.

Notice that in Apache, settings are referred to as Directives.

You should read this document in conjunction with the Directive Quick Reference Guide, and Dictionary dictionary.

You can also access them locally like this (if you have installed httpd-manual rpm):

$ elinks http://localhost/manual/mod/directives.html
$ elinks http://localhost/manual/mod/directive-dict.html
$ elinks http://localhost/manual/mod/quickreference.html

Let’s take a look at some of these setting in turn:

The ‘ServerRoot’ setting

The ServerRoot sets the location where all of Apache’s configurations and logs are stored. Some

RHCE – Controlling access using Apache’s Order, Deny, and Allow directives on CentOS/RHEL 7

Apache let’s you Allow/Deny access based on who is requesting access using the Order directive which is used in conjunction with the Allow and Deny directives.

You can sepcify multiple Allow and Deny rules like this:

Deny from {ip address}
Allow from {}
Deny from

Order deny,allow

Take the RHCSA Quiz

This article is part of our RHCSA Study guide (click on the yellow tab on the far left). By the end of this article you should be able to answer the following questions:















RHCE – Setting up login based authentication using Apache on CentOS/RHEL 7

In the previous tutorial, we saw how we can host multiple websites on the same box using vhosts. Now we’ll look at how we can configure Apache to password protect some web content. In Apache you can set up authentication so that when a user attempts to access a given folder’s content, then they will get a prompt to enter a valid username and password. There’s 2 ways to do this:

  • Setup user-based security – This is where you only give one user account access to restricted part of your website
  • Setup group-managed content – this is where you give a group of people access to a restricted part of your website

Need to rewrite to article like this: first create 2 users tom and jerry. Then setup to only give tom access.

RHCE – How To Set Up Apache Virtual Hosts on CentOS/RHEL 7

Virtual Hosts is one of Apache’s most powerful and commonly used feature. Virtual Hosts (aka vhosts) let’s allows you to host multiple websites on a single machine. There are 2 big advantages to this:

  • Rather than needing one ip address per website, you know just need one ip address for the machine.
  • A lot of machines capacity might not get used if it just hosts a single website. So having multiple websites on a single machine will make better use of your machine’s computing capacity

There are a few ways to setup vhosts, but we’ll walk through one of typical most common ways to create vhosts. In our example we have 2 websites that we want to host on our box, they are:


To start with we first need to create a content directory

RHCE – Create a hello world CGI app on CentOS/RHEL 7

Common Gateway Interface (CGI) is a protocol that let’s you run custom scripts via the web. It’s not as commonly used as before, but you still need to know this as part of the RHCE exam objectives.

In Apache, there is a default folder where you can place scripts in, which will then get handled by the CGI protocol. This default folder is declared in the main Apache config file, here’s the relevant extract:

    # Redirect: Allows you to tell clients about documents that used to
    # exist in your server's namespace, but do not anymore. The client
    # will make a new request for the document at its new location.
    # Example:

RHCE – Make websites more secure by setting up HTTPS and SSL/TLS for CentOS 7

So far we have configured web servers to allow connections via the http protocol. However http is not secure which is why it’s better to use https.

When using https, we actually encrypt all data traffic using Symmetric and Asymmetric Encryption.

To setup the above encryption system on our Apache server, we need to first to install the ssl addon module that will allow Apache to be able to communicate on the SSL/TLS layer:

$ yum install mod_ssl

Next we need to install the software that is used for generating public-private key-pairs, so that we can create a key-pair for our web server.

$ yum install openssl

Next we create the private key and it’s csr file. We generate the private key by running the following:

$ openssl genpkey -algorithm RSA -out -pkeyopt rsa_keygen_bits:2048


Apache – How does setting up SSL/TLS and HTTPS improve security?

Nowadays it’s common practice to setup web servers to communicate with web browsers using https? But how does https provide better security than plain old http?

we’ll use the Bob and Alice analogy to help explain this. Let’s say Alice wants to buy a book from a website called ‘’. Let’s also say that this website is hosted on a webserver that managed by Bob, who hasn’t got round to setting up https. So if Alice attempts to make the purchase, then we would have this scenario:

      Alice's web browser                                   															

What is the purpose of a Certificate Signing Request (CSR)

In order for a web browser (e.g. firefox) to establish a secure https session with an https enabled Apache web server, it needs a copy the public key part of the web server’s public-private key-pair. This is done by requesting a digital certificate from a Certificate Authority (CA).

A Certificate Authority is a trusted third party that is fully and completely trusted by all the main web browsers (Firefox, Chrome, Microsoft Edge, Safari….etc ). At it’s heart, you can think of a CA has a public-private key-pair. But when it comes CA public-private keys, the private key is used for creating encrypted files. These encrypted files are called Digital Certificates (and are often called SSL Certificates). Whereas the CA’s public key (aka root certificates) is used for decrypting encrypted files