Apache 2 - proxy

Principle

The proxy module allow you to expose a resource that is not directly accessible.

For instance it can redirect remote user to a specific server that can be host on a different machine or port through a simple URL.

Proxy VS redirection

Header text	Proxy	Redirection
Main usage	Expose a resource that is not directly accessible Provide a nicer URL through standard HTTP port instead of http://server:port/service	Signal a change or redirect to the HTTPS web-site
Action	Hidden to the user. From user point of view this is just a standard URL / service It's the server that performs the proxy actin	Explicit The server just serve the new URL It's the client that will create a new connection - See Apache_2#Principle

Internet limits: why do we need a proxy?

Some application are not available from outside…

• For security reasons [default URL is not allowed]

• Due to network issues

How does Apache2 mod_proxy work?

The Apache2 proxy module allow you to provide access through transparent redirection.

It relies on:

• Already open port (80 or 443)
• Redirection rule
• Each service URL must be unique
• The target service must be reachable by the web server

As you can see on the previous example, the services will be accessible using some dedicated URL. Remote “http://myServer/myService” will redirect to “http://localhost:8081”

→ The mod_proxy is none intrusive. You don’t have to change anything in the original service configuration. Apache2 will handle all the transformations.

Proxy / redirect / rewrite - HTTP request processing

When Apache2 receive a request it will be process in the following order:

The evaluation order is:

1. Mod_proxy
2. Mod_rewrite
3. Other modules
4. Serve requested resources if no rule should apply

So, even if you enable a full redirection to HTTPS you can still use some HTTP service through mod_proxy (because mod_proxy is the 1st to be evaluate).

Installation

Enable proxy module

a2enmod proxy proxy_http proxy_ajp 
a2enmod proxy_html xml2enc

Configure proxy redirections

You can configure the redirections in 2 ways:

• Through your virtual host configuration
• Through the module configuration file

Module configuration file

You have to edit / create the configuration file.

vim /etc/apache2/mods-enabled/proxy.conf

Virtual host

Just edit again your previous V.Host:

vim /etc/apache2/sites-available/myServer.conf

V.Host proxy declaration

Adjust your V.Host configuration to:

<VirtualHost *:80>
	ServerName dev.daxiongmao.eu
	ServerAlias www.dev.daxiongmao.eu *.dev.daxiongmao.eu
	ServerAdmin guillaume@qin-diaz.com

	### LOG
	LogLevel warn
	ErrorLog ${APACHE_LOG_DIR}/dev.daxiongmao.eu/error.log
	CustomLog ${APACHE_LOG_DIR}/dev.daxiongmao.eu/access.log combined
	
        ### Redirect all traffic to HTTPS website
        RewriteEngine On
        RewriteCond %{HTTPS} off        
        RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} 
	redirect permanent / https://myServer/

	### No proxy here because I only want to use HTTPS
</VirtualHost>

<VirtualHost *:443>
...

        #############################
        # Proxy configuration
        #############################
        # Enable proxy
        ProxyVia On
        ProxyPreserveHost On
        ProxyRequests Off
        ProxyErrorOverride Off

        ## SSL support (allow to redirect to other SSL sites)
        SSLProxyEngine On
        SSLProxyVerify none
        SSLProxyCheckPeerCN off
        SSLProxyCheckPeerName off

        <Proxy *>
             AddDefaultCharset off
             
             #### You must accept proxy from everywhere *
             #### Access control is done in each directory ||  location

             ## Old Apache2 (before 2.4) syntax
             #Order allow,deny
             #allow from all
 
             ## Apache 2.4 syntax
             Require all granted
             Satisfy Any
        </Proxy> 

	########################
	# Standard Web application - No proxy required
	########################

        #### Direct access without further configuration
	ProxyPass /maintenance !
	ProxyPass /menu !
	ProxyPass /ssl !

        #### Standard URL filters
	# PhpMyAdmin
	<Location /phpmyadmin>
                ProxyPass !

                # Apache 2.4 syntax
                Require local
                # LAN and VPN
                require ip 172.16.50
                require ip 172.16.60
                # Specific hosts
                require host dev.daxiongmao.eu
	</Location>

         #### Alias 
         # PHPSecInfo
         Alias   /phpsec   /var/www/phpsecinfo
         <Location /phpsec >
                 ProxyPass !

                # Apache 2.4 syntax
                Require all granted
         </Location>


	########################
	# Proxy redirections
	########################

	# Proxy to a Java application running over Tomcat
	ProxyPass /webdav ajp://localhost:8009/webdav/
	ProxyPassReverse /webdav ajp://localhost:8009/webdav 	

	# Proxy to a Java application running over Tomcat, with IP filter
	<Location /manager>
		ProxyPass ajp://localhost:8009/manager/
		ProxyPassReverse ajp://localhost:8009/manager/

                ### Apache < 2.4
		#Order allow,deny
		#Allow from 127.0.0.1 192.168.1.0/24 193.12.118.196

                ### Apache 2.4
                Require local
                Require ip 192.168.1
                Require host 193.12.118.196
	</Location>

        # Proxy to another server
        ProxyPass /jira http://192.168.1.12:8080/jira
        ProxyPassReverse /jira http://192.168.1.12:8080/jira

        ## Proxy to webmin
        <Location /webmin/>
           ProxyPass http://localhost:10000/
           ProxyPassReverse http://localhost:10000/

            # Apache 2.4 syntax
            Require local
            # LAN and VPN
            require ip 172.16.50
            require ip 172.16.60
       </Location>

      ## Proxy to RabbitMQ
      <Location /rabbitmq/>
         ProxyPass http://smartcard-mq:15672/
         ProxyPassReverse http://smartcard-mq:15672/

         ### Apache < 2.4
         #Order deny,allow
         #Deny from all
      
         ### Apache 2.4
         Require all denied
      </Location>

</VirtualHost>

Some notes:

• Do NOT put a / after the target URL
• Do NOT use / as ProxyPass source, use the previous redirect permanent instead

Apply settings

Apply changes and test result

service apache2 restart

For example, Navigate to http://myServer/jira

Thanks

Special thanks to Julien Rialland for his insight regarding this part!

• Julien's blog: http://jrialland.wordpress.com/
• Julien's LinkedIn: http://fr.linkedin.com/in/julienrialland