Tag Archives: apache

Monitor your servers with phpservermonitor

I have a handful of servers and for years I’ve been wanting to get some sort of monitoring in place. Today I tried out php server monitor and found it was pretty easy to set up and use.

Download

The installation process was pretty straightforward.

  • Install PHP, mysql, and apache
  • Create database, user, password, and access rights for mysql
  • Download .tar.gz and extract to /var/www
  • Configure Apache site file to point to phpservermonitor directory
  • Navigate to the IP / URL of your apache server and run the installation script

The above process is documented fairly well on their website. I configured this to run on my Raspberry Pi 2. This was my process:

Install dependencies:

sudo apt-get install php5 php5-curl php5-mysql mysql-server

Configure mysql:

sudo mysql_secure_installation

Create database:

mysql -u root -p
create database phpservermon;
create user 'phpservermon'@'localhost' IDENTIFIED BY 'password';
 grant all privileges on phpservermon.* TO 'phpservermon'@'localhost'; 
flush privileges;

Extract phpservermon to /var/www and grant permissions

tar zxvf <phpservermon_gzip_filename> -C /var/www
sudo chown -R www-data /var/www/*

Configure php:

sudo vim /etc/php5/apache2/php.ini
#uncomment date.timezone and set your timezone
date.timezone = "America/Boise"

Configure apache:

sudo cp /etc/apache2/sites-available/default /etc/apache2/sites-available/phpservermon

#Modify /etc/apache2/sites-available/phpservermon server root to point to directory above, also add a ServerName if desired

sudo a2ensite phpservermon
sudo service apache2 reload

Configure cron (I have it check every minute but you can configure whatever you like)

*/1 * * * * /usr/bin/php /var/www/phpservermon/cron/status.cron.php

Navigate to the web address you’ve configured in apache and follow the wizard.

It’s pretty simple but it works! A nice php application to monitor websites and services.

 

Purge Varnish cache by visiting URL

I came across a need to allow web developers to purge Varnish cache. The problem is the developers aren’t allowed access to the production machine and our web application firewall blocks purge requests. I needed for there to be a way for them to simply access a page hosted on the webserver and cause it to purge its own varnish cache.

I was able to accomplish this by placing a PHP file in the webserver’s directory and controlling access to it via .htaccess. Thanks to this site for the php script and this one for the .htaccess guidance.

Place this PHP file where the web devs can access it, making sure to modify the $hostname variable to suit your needs and to rename the file to have a .php extension.

<?php

#Simple script to purge varnish cache
#Adapted from the script from http://felipeferreira.net/index.php/2013/08/script-purge-varnish-cache/
#This script runs locally on the webserver and will purge all cached pages for the site specified in $hostname
#Modify the $hostname parameter below to match the hostname of your site

$hostname = $_SERVER['SERVER_NAME'];

header( 'Cache-Control: max-age=0' );

$port     = 80;
$debug    = false;
$URL      =  "/*";

purgeURL( $hostname, $port, $URL, $debug );

function purgeURL( $hostname, $port, $purgeURL, $debug )
{
    $finalURL = sprintf(
        "http://%s:%d%s", $hostname, $port, $purgeURL
    );

    print( "<br> Purging ${finalURL} <br><br>" );

    $curlOptionList = array(
        CURLOPT_RETURNTRANSFER    => true,
        CURLOPT_CUSTOMREQUEST     => 'PURGE',
        CURLOPT_HEADER            => true ,
        CURLOPT_NOBODY            => true,
        CURLOPT_URL               => $finalURL,
        CURLOPT_CONNECTTIMEOUT_MS => 2000
    );

    $fd = true;
    if( $debug == true ) {
        print "<br>---- Curl debug -----<br>";
        $fd = fopen("php://output", 'w+');
        $curlOptionList[CURLOPT_VERBOSE] = true;
        $curlOptionList[CURLOPT_STDERR]  = $fd;
    }

    $curlHandler = curl_init();
    curl_setopt_array( $curlHandler, $curlOptionList );
    $return = curl_exec($curlHandler);

    if(curl_error($curlHandler)) {
    print "<br><hr><br>CRITICAL - Error to connect to $hostname port $port - Error:  curl_error($curl) <br>";
    exit(2);
 }

    curl_close( $curlHandler );
    if( $fd !== false ) {
        fclose( $fd );
    }
    if( $debug == true ) {
        print "<br> Output: <br><br> $return <br><br><hr>";
    }
}
?>

<title>Purge cache</title>
Press submit to purge the cache
<form method="post" action="<?php echo $PHP_SELF;?>">
<input type="submit" value="submit" name="submit">
</form>

Place (or append) the following .htaccess code in the same directory you placed the php file:

#Only allow internal IPs to access cache purge page
<Files "purge.php">
    Order deny,allow
    Deny from all
    SetEnvIf X-Forwarded-For ^10\. env_allow_1
    Allow from env=env_allow_1
    Satisfy Any
</Files>

The above code only allows access to the purge.php page from IP addresses beginning with “10.” (internal IPs)

This PHP / .htaccess combo allowed the web devs to purge cache without any system access or firewall rule changes. Hooray!

Find top 10 requests returning 404 errors

I had a website where I was curious what the top 10 URLs that were returning 404s were along with how many hits those URLs got. This was after a huge site redesign so I was curious what old links were still trying to be accessed.

Getting a report on this can be accomplished with nothing more than the Linux command line and the log file you’re interested in. It involves combining grep, sed, awk, sort, uniq, and head commands. I enjoyed how well these tools work together so I thought I’d share. Thanks to this site for giving me the inspiration to do this.

This is the command I used to get the information I wanted:

grep '404' _log_file_ | sed 's/, /,/g' | awk {'print $7'} | sort | uniq -c | sort -n -r | head -10

Here is a rundown of each command and why it was used:

  • grep ‘404’ _log_file_ (replace with filename of your apache, tomcat, or varnish access log.) grep reads a file and returns all instances of what you want, in this case I’m looking for the number 404 (page not found HTTP error)
  • sed ‘s/, /,/g’ Sed will edit a stream of text in any way that you specify. The command I gave it (s/, /,/g) tells sed to look for instances of commas followed by spaces and replace them with just commas (eliminating the space after any comma it sees.) This was necessary in my case because sometimes the source IP address field has multiple IP addresses and it messed up the results. This may be optional if your server isn’t sitting behind any type of reverse proxy.
  • awk {‘print $7’} Awk has a lot of similar functions to sed – it allows you to do all sorts of things to text. In this case we’re telling awk to only display the 7th column of information (the URL requested in apache and varnish logs is the 7th column)
  • sort This command (absent of arguments) sorts our results alphabetically, which is necessary for the next command to work properly.
  • uniq -c This command eliminates any duplicates in the results. The -c argument adds a number indicating how many times that unique string was found.
  • sort -n -r Sorts the results in reverse alphabetical order. The -n argument sorts things numerically so that 2 follows 1 instead of 10. -r Indicates to reverse the order so the highest number is at the top of the results instead of the default which is to put the lowest number first.
  • head -10 outputs the top 10 results. This command is optional if you want to see all the results instead of the top 10. A similar command is tail – if you want to see the last results instead.

This was my output – exactly what I was looking for. Perfect.

2186 http://<sitename>/source/quicken/index.ini
2171 http://<sitename>/img/_sig.png
1947 http://<sitename>/img/email/email1.aspx
1133 http://<sitename>/source/quicken/index.ini
830 http://<sitename>/img/_sig1.png
709 https://<sitename>/img/email/email1.aspx
370 http://<sitename>/apple-touch-icon.png
204 http://<sitename>/apple-touch-icon-precomposed.png
193 http://<sitename>/About-/Plan.aspx
191 http://<sitename>/Contact-Us.aspx

Speed up WordPress in CentOS7 using caching

It has recently come to my attention that WordPress has a serious design flaw: it’s trivially easy to execute a denial of service attack against it in its default state. One simply has to hold down F5 to cause the site to slow to a crawl and in many cases crash entirely.

The reason behind this is that every single page request turns into the server parsing PHP code and executing a database call. Holding down F5 initiates hundreds of page view requests, which turn into hundreds of PHP code execution threads (each taking up CPU and memory) and hundreds of database calls. The server becomes quickly overwhelmed and runs out of resources.

The solution to this problem (on CentOS 7 at least) is a combination of php-fpm, zendopcache, APC, varnish and W3 Total Cache. It’s definitely more complicated but it eliminates this problem and massively increases site load times and general responsiveness.

Repositories

To install the required addons we will need to have the epel repository enabled:

yum -y install epel-release

zend-opcache

This caches PHP opcode to greatly speed up PHP code execution. It’s included in later versions of PHP but alas CentOS 7 is stuck on PHP 5.4, which does not include such caching. You have to install it manually. Thanks to this site for the information.

sudo yum -y install php-pecl-zendopcache

apc

This is another kind of of cache – this time for database operations.

sudo yum -y install php-pecl-apcu php-devel gcc
sudo pecl install apc
#accept defaults when prompted

php-fpm

php-fpm is a different way to serve up PHP code. Instead of apache running a module to interpret php code, it will send all php requests to a separate PHP server, optimized for speed. That php server will interpret the code and return the results to your browser.

sudo yum -y install php-fpm
sudo systemctl enable php-fpm

Modify your apache config to forward all php requests to php-fpm. Be sure to modify this to match your site URL setup:

sudo sh -c "echo '
    <LocationMatch \"^/(.*\.php(/.*)?)$\"> 
        ProxyPass fcgi://127.0.0.1:9000/var/www/html/\$1 
    </LocationMatch>' >> /etc/httpd/conf/httpd.conf"

Varnish

Varnish is a reverse proxy server optimized for caching pages. It sits between your visitors and your webserver and caches whatever it can to increase responsiveness and speed. This site pointed me in the right direction for configuring Varnish  in CentOS 7.

sudo yum -y install varnish
sudo systemctl enable varnish

Change apache to listen on port 8080 instead of port 80:

sudo sed -i /etc/httpd/conf/httpd.conf -e 's/Listen 80/&80/'

Change varnish to listen on port 80 instead of port 6081:

sudo sed -i /etc/varnish/varnish.params -e 's/VARNISH_LISTEN_PORT=6081/VARNISH_LISTEN_PORT=80/g'

Now we need to configure Varnish to properly cache wordpress sites. I found the configuration from this site to be the most helpful. I normally include code blocks to copy and paste but the configuration file is pretty big.

Instead, click here for the configuration code, then copy the whole page and paste it into your terminal.

Update 12/28/2016: I’ve updated the varnish configuration code slightly to allow the “purge all caches” button of W3 Total cache to work. Thanks to this site for pointing me in the right direction and this thread for getting me there.

After varnish has been configured, restart your new PHP / caching stack:

sudo systemctl restart httpd varnish php-fpm

Logging

Update: added this section on 11/4/2016

By default varnish does not log its traffic. This means that your apache log will only log things varnish does not cache. We have to configure varnish to log traffic so you don’t lose insight into who is visiting your site.

Update 2/14/2017:  I’ve discovered a better way to do this. The old way is still included below, but you really should use this other way.

New way:

CentOS ships with some systemd scripts for you. You can use them out of the box by simply issuing

systemctl start varnishncsa
systemctl enable varnishncsa

If you are behind a reverse proxy then you will want to tweak the varnishncsa output a bit to reflect x-forwarded-for header values (thanks to this github discussion for the guidance.) Accomplish this by appending a modified log output format string to /lib/systemd/system/varnishncsa.service:

sudo sed -i /lib/systemd/system/varnishncsa.service -e "s/ExecStart.*/& -F \'%%{X-Forwarded-For}i %%l %%u %%t \"%%r\" %%s %%b \"%%{Referer}i\" \"%%{User-agent}i\"\' /g"

Lastly, reload systemd configuration, enable, and start the varnishncsa service:

sudo systemctl daemon-reload
sudo systemctl enable varnishncsa
sudo systemctl start varnishncsa

Old way:

First, enable rc.local

sudo chmod +x /etc/rc.local
sudo systemctl enable rc-local #you can ignore errors here

Next, add this entry to the rc.local file:

sudo sh -c 'echo "varnishncsa -a -w /var/log/varnish/access.log -D -P /var/run/varnishncsa.pid" >> /etc/rc.local'

If your varnish server is behind a reverse proxy (like a web application firewall) then modify the above code slightly (thanks to this site for the information on how to do so)

sudo sh -c "echo varnishncsa -a -F \'%{X-Forwarded-For}i %l %u %t \"%r\" %s %b \"%{Referer}i\" \"%{User-agent}i\"\' -w /var/log/varnish/access.log -D -P /var/run/varnishncsa.pid >> /etc/rc.local"

W3 Total Cache

The improvements above will greatly increase your speed and eliminate the F5 denial of service issue. The last bit to make it even sweeter is to install the W3 Total Cache wordpress plugin. Thanks to this site for the information that pointed me in the right direction.

There are a ton of options in W3 Total cache that are beyond the scope of this tutorial. For our purposes we will enable the following options in the General Settings tab of the plugin:

opcode-database-object

Opcode cache: Opcode:Zend Opcache

Database cache: Check enable, select Opcode: Alternative PHP Cache (APC / APCu)

Object cache: Check enable, select Opcode: Alternative PHP Cache (APC / APCu)

proxy

Reverse Proxy: Check “Enable reverse proxy caching via varnish”
Specify 127.0.0.1 in the varnish servers box. Click save all settings.

Full speed ahead

With all of these pieces into place your site is definitely more complicated, but it is also much faster to load. Enjoy.

Troubleshooting

If you go through all these steps only to see this very non-descriptive message:

File not found

it means you have PHP forwarding to the wrong directory. Modify the LocationMatch section you inserted at the bottom of /etc/httpd/conf/httpd.conf earlier to ensure the correct directory structure is passed for php files.

Install WordPress on CentOS 7 with SELinux

I’ve been frustrated lately with the number of tutorials for installing WordPress on CentOS 7 that say to simply turn SELinux off. This is an unacceptable workaround. It’s simply lazy administration. SELinux is not designed to make your job harder (although it can do that pretty well), it’s there to make your system safer.

I have scoured the internet and pieced together bits of information from several sources – mainly here, here, and here to put together a tutorial that walks you through how to install WordPress in CentOS7 while keeping SELinux turned on.

It took a lot of reading to understand SELinux, but once you understand it, it makes a whole lot more sense. Go figure.

Apache

Install required packages:

sudo yum -y install httpd
sudo systemctl enable httpd

Modify apache config to allow mod_rewrite:

sudo sed -i /etc/httpd/conf/httpd.conf -e 's/AllowOverride None/AllowOverride All/g'

Open necessary firewall ports:

sudo firewall-cmd --add-service=http --permanent
sudo systemctl restart firewalld

Start apache:

sudo systemctl start httpd

Navigate to your new site to make sure the testing page comes up.

Update 11/4/2016: If you are behind a reverse proxy such as varnish or a web application firewall, you will want to modify your apache configuration to log x-forwarded-for IPs to make the logs more meaningful:

sudo sed -i /etc/httpd/conf/httpd.conf -e 's/%h/%{X-Forwarded-For}i/g'

MariaDB

Install:

sudo yum -y install mariadb-server mariadb
sudo systemctl enable mariadb

Run initial mysql configuration to set database root password

sudo systemctl start mariadb
sudo mysql_secure_installation

Create a wordpress database and user:

mysql -u root -p 
#enter your mysql root password here
create user wordpress;
create database wordpress;
GRANT ALL PRIVILEGES ON wordpress.* To 'wordpress'@'localhost' IDENTIFIED BY 'password';
quit;

WordPress

Install PHP and restart apache

sudo yum -y install php php-mysql php-gd php-ldap php-odbc php-pear php-xml php-xmlrpc php-mbstring php-snmp php-soap curl
sudo systemctl restart httpd

Configure base wordpress directory

Download, extract, and set permissions for your wordpress installation:

wget https://wordpress.org/latest.zip
sudo unzip latest.zip -d /var/www/html
sudo chown apache:apache -R /var/www/html/wordpress

Optional: Change Apache document root so you don’t need to tack /wordpress at the end of the url:

sudo sed -i /etc/httpd/conf/httpd.conf -e 's/DocumentRoot \"\/var\/www\/html/&\/wordpress/g'
sudo systemctl restart httpd

Configure upload directory

If you want users to upload content, then you will want to assign the http_sys_rw_content_t selinux security context for the wp-uploads directory (create it if it doesn’t exist)

sudo mkdir /var/www/html/wordpress/wp-content/uploads
sudo chown apache:apache /var/www/html/wordpress/wp-content/uploads
sudo semanage fcontext -a -t httpd_sys_rw_content_t "/var/www/html/wordpress/wp-content/uploads(/.*)?"
sudo restorecon -Rv /var/www/html/wordpress/wp-content/uploads

Run the wizard

In order for the wizard to run properly we need to temporarily give the wordpress directory httpd_sys_rw_content_t selinux context

sudo chcon -t httpd_sys_rw_content_t /var/www/html/wordpress/

Now navigate to your new website in a browser and follow the wizard, which will create a wp-config.php file inside the wordpress directory. Once your site is properly set up, restore the original security context for the wordpress directory:

sudo restorecon -v /var/www/html/wordpress/

Success! Everything is working within the proper SELinux contexts.

Troubleshooting

Permission denied when accessing /wordpress

The obvious thing to check is to make sure the directory /var/www/html/wordpress has the ownership set to apache. That didn’t fix my issue, though. Thanks to serverfault I narrowed this down to a selinux permissions issue.  Changing the selinux context to httpd_sys_content_t for the wordpress folder fixed the issue.

sudo semanage fcontext -a -t httpd_sys_content_t /var/www/html/wordpress/
sudo restorecon -v /var/www/html/wordpress/

Sorry, but I can’t write the wp-config.php file.

“You can create the wp-config.php manually and paste the following text into it.”

I had a suspicion that writing files was also a selinux issue. This was confirmed when I decided to tail /var/log/audit/audit.log and found this when the wordpress installer tried to write wp-config.php:

type=AVC msg=audit(1475596102.558:16868): avc: denied { write } for pid=5751 comm="httpd" name="wordpress" dev="dm-0" ino=68494934 scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:object_r:httpd_sys_content_t:s0 tclass=dir
type=SYSCALL msg=audit(1475596102.558:16868): arch=c000003e syscall=21 success=no exit=-13 a0=7f9f4b931478 a1=2 a2=0 a3=1 items=0 ppid=5740 pid=5751 auid=4294967295 uid=48 gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=4294967295 comm="httpd" exe="/usr/sbin/httpd" subj=system_u:system_r:httpd_t:s0 key=(null)

This led me to find this great explanation from francispereira on how to get wordpress and selinux to peacefully coexist. Also thanks to the excellent Redhat Manual for more information on what to do, combined with this very helpful guide from serverlab.

First, we need to temporarily grant httpd_sys_rw_content_t to the wordpress directory. This is to allow the initial wizard to create the wp-config.php file.

sudo chcon -t httpd_sys_rw_content_t /var/www/html/wordpress/

Now you can run the wizard and it will work properly.

Once your site is set up, restore the context to http_sys_content_t

sudo restorecon -v /var/www/html/wordpress/

Block annoying bots with Apache .htaccess

Recently one of my sites has been having its database crash repeatedly. Investigation reveals it always happens while an aggressive bot is crawling it. Since the site is small it was causing the database to run out of memory and die.

The Web Application Firewall that this site is behind frustratingly does not have a feature for blocking user agents. I decided to resort to Apache on the webserver itself to serve as a gatekeeper. The user agent in question? flipboard proxy. It also conveniently appears to ignore robots.txt.

Thanks to this article I learned the details on how to get Apache to block this particular user agent. Creating an .htaccess file (if it doesn’t already exist) and putting it in the root directory of the website causes it to apply to the entire site. Within the .htaccess file, place the following directives:

#block bad bots with a 403
#SetEnvIfNoCase User-Agent "facebookexternalhit" bad_bot
SetEnvIfNoCase User-Agent "Twitterbot" bad_bot
SetEnvIfNoCase User-Agent "Baiduspider" bad_bot
SetEnvIfNoCase User-Agent "MetaURI" bad_bot
SetEnvIfNoCase User-Agent "mediawords" bad_bot
SetEnvIfNoCase User-Agent "FlipboardProxy" bad_bot
<Limit GET POST HEAD>
 Order Allow,Deny
 Allow from all
 Deny from env=bad_bot
</Limit>

Save the file in the root of your website and make sure its permissions are such that your apache server can read the file. Success! Flipboard proxy (and other bad bots) no longer crashes the site. Instead, it gets served a 403 – Forbidden page for every request it makes.

Fix Apache Permission Denied errors

The other day I ran the rsync command to migrate files from an old webserver to a new one. What I didn’t notice right away was that the rsync changed the permissions of the folder I was copying into.

The problem presented itself with a very lovely 403 forbidden error message when trying to access any website that server hosted. Checking the logs (/var/log/apache2/error.log on my Debian system) revealed this curious message:

[error] [client 192.168.22.22] (13)Permission denied: access to / denied

This made it look like apache was denying access for some reason. I verified apache config and confirmed it shouldn’t be denying anything. After some head scratching I came across this site which explained that Apache throws that error when it encounters filesystem access denied error messages.

I was confused because /var/www, where the websites live, had the appropriate permissions. After some digging I found that the culprit in my case was not /var/www, but rather the /var directory underneath /var/www. For some reason the rsync changed /var to not have any execute permissions (necessary for folder access.)  A simple

chmod o+rx /var/

resolved my problem. Next time you get 403 it could be underlying filesystem issues and not apache at all.

Use Sophos User portal and WAF on same port

The Sophos UTM firewall is a great piece of security software. It is designed with businesses in mind but is also free for home use. It has many features, two of which (User Portal and Web Application Firewall) compete for the same port – TCP 443 (https.) This is a shame if you want to run both services simultaneously but only have one IP address.

For some reason the folks at Astaro (Sophos) have not engineered a way to allow the WAF and User Portal to play nicely, saying on their forums to just configure them to use different ports. What if you have people who are behind firewalls that only allow ports 80 and 443? You are stuck.

I didn’t like that answer so I set out to research a way around this. The solution to this problem lies with Apache and its reverse proxy feature. A reverse proxy is a webserver that receives HTTP requests and forwards them to some other location, then returns the response.

My solution to the “I want both WAF and User Portal to use the same port” problem is to put the user portal on a different, internal-only port, spin up a small apache server, configure it to forward all requests to the user portal address:port combination, and add it as a real server in the sophos WAF.

Change user portal port

Easy enough: Go to Management / User Portal / Advanced tab, scroll down to the “Network Settings” section and pick a different port, then click apply.

Spin up a reverse proxy web server

I went with Ubuntu Server 14.04 so I could have newer software packages.

  1. Install apache
    sudo apt-get install apache2
  2. Enable needed modules
    sudo a2enmod ssl
    sudo a2enmod proxy
    sudo a2enmod proxy_http
  3. Configure apache to proxy all requests to your user portal
    #Add the following to default-ssl.conf
    sudo vim /etc/apache2/sites-enabled/default-ssl.conf
    SSLProxyEngine On
    #Enable the next 3 lines if you want to ignore certificate errors
    #SSLProxyVerify none
    #SSLProxyCheckPeerCN off
    #SSLProxyCheckPeerName off
    
    #Configure the reverse proxy to forward all requests
    ProxyPass / https://<your firewall IP>:<port you chose earlier>/
    ProxyPassReverse / https://<your firewall IP>:<port you chose earlier>/
    #Make sure slashes are at the end (important)
  4. Restart apache
    sudo service apache2 reload

 Add your reverse proxy to Sophos UTM

  1. Add your proxy server as a real webserver. Go to Webserver protection / Web Application Firewall / Real Webservers and add your proxy server address. Make sure the type is “Encrypted HTTPS” (important.)
  2. Add your desired URL as a virtual server and point to your proxy real server (Virtual Webservers tab.) You’ll have to have an SSL certificate generated, which is beyond the scope of this post.

Caveats

The above configuration will work with every function of the User Portal.. except for the HTML5 VPN gateway. For some inexplicable reason it has scripts hard coded to use the root directory, which Apache won’t proxy properly even if you have rewrite rules in place. I fiddled with this for hours before I finally gave up and looked elsewhere for an HTML5 VPN solution.

Guacamole

It’s more than just dip, it’s an excellent open source HTML5 RDP/VNC/SSH gateway. Unlinke Sophos’s option, guacamole properly handles being in a subdirectory. Unfortunately it is very frustrating and user un-friendly to configure. I decided just to use a pre-configured VM appliance from Green Reed Technology. It’s an excellent appliance and “just works” – a much better experience than wrestling with archaic configuration files. You can get it from here.

 

Mythweb broken after upgrading to Ubuntu 14.04

I recently upgraded my mythbuntu installation from 12.04 to 14.04. For some reason the distribution upgrade tool failed on me. I had to upgrade manually by updating everything in /etc/apt/sources* to point to trusty instead of precise.

After a reboot I was surprised to find out that everything upgraded beautifully except for one thing – mythweb. When I tried to start Apache I was greeted with this lovely message:

* The apache2 configtest failed.
Output of config test was:
AH00526: Syntax error on line 30 of /etc/apache2/sites-enabled/mythweb.conf:
Illegal option AllowAll
Action 'configtest' failed.
The Apache error log may have more information.

It turns out Ubuntu 14.04 uses a different version of Apache with different syntax, which breaks the configuration. Thanks to this post I found the fix to be relatively easy:

sudo rm /etc/apache2/sites-available/mythweb.conf
sudo dpkg-reconfigure mythweb
sudo /etc/init.d/apache2 start

After that was done, all was well and upgraded.

Add x-forwarded-for header to Apache

If you happen to be running your site behind a web application firewall you will notice that initially you will not be able to determine the true source of traffic coming to your server. The default setup for Apache will only show traffic coming from the firewall itself.

To fix this, you need to tweak the LogFormat parameters in /etc/apache2/apache2.conf (for Debian distros) or wherever your apache config file is in other distros. Per here, you need to add

 %{X-Forwarded-For}i

to your config file. Here is an example setup successfully implementing X forwarded For as well as maintaining logging the IP of the WAF itself (in case you have more than one..)

LogFormat "%v:%p %{X-Forwarded-For}i %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined
LogFormat "%{X-Forwarded-For}i %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" combined
LogFormat "%{X-Forwarded-For}i %h %l %u %t \"%r\" %>s %O" common
LogFormat "%{Referer}i -> %U" referer
LogFormat "%{User-agent}i" agent