Posts

Stefan Helander

How to convert a certificate PFX file to CRT/KEY using openssl

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Your PFX certificate file is protected with a password. It can be converted to CRT and KEY files using SSL:

openssl pkcs12 -in certfile.pfx -nocerts -out keyfile-encrypted.key

When you enter this command you will be asked to type in the pfx file password in order to extract the key. You will be asked to enter a passphrase for the encrypted key. The key will be stored in keyfile-encrypted.key.

The exported keyfile is encrypted but you might need it in unencrypted format. To unencrypt the key, do:

openssl rsa -in keyfile-encrypted.key -out keyfile.key

You will be asked for the passphrase that you entered in the previous step. The unencrypted key will be stored in keyfile.key.

Then it is time to extract the certificate:

openssl pkcs12 -in certfile.pfx -clcerts -nokeys -out certfile.crt

Again, you will need to enter the pfx file password in order to extract the certificate. The certificate will be stored in certfile.crt.

Stefan Helander

High load on CPU and disk I/O every hour (Apache, MySQL and mod_pagespeed on Ubuntu)

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On one of my Ubuntu servers I noticed a significant peak in CPU load (load average, LA) and disk I/O about every hour. At first, I suspected that MySQL was the cause of this, doing some houeskeeping or garbage cleaning.

However, it turned out it was caused by the Apache module mod_pagespeed. The high load occuered when pagespeed was cleaning out it’s cache.

The solution was to locate the cache on tmpfs instead. This was done by editing the file /etc/apache2/mods-available/pagespeed.conf and change the location of the cache by the line (/run is located on tmpfs which is RAM memory):

ModPagespeedFileCachePath "/run/cache/mod_pagespeed/"

Then restart Apache by:

service apache2 restart
Stefan Helander

Error 404 when trying to password protect administrator folder in Joomla using Apache htaccess

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When protecting the administrator folder in Joomla using Apache htaccess to increase the security of the website (which by the way is a good thing to do to prevent too interested individuals to peek where they shouldn’t), you might get an error 404 message when trying to access administrator and the expected password prompt never appears.

The cause can be that the server is configured to allow user defined error pages stored in for example the error folder. If some of the error files are missing the above mentioned problem can occur. Make sure you have the correct folder name and file names for your error files.

This particular problem occured for me when I moved a Joomla site from one hosting provider to another and by mistake also replaced the error folder with the one from the old hosting provider which had a completely different file name structure for the error message files.

Stefan Helander

Error message in Apache log file: “Options FollowSymLinks or SymLinksIfOwnerMatch is off which implies that RewriteRule directive is forbidden”

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The error message "Options FollowSymLinks or SymLinksIfOwnerMatch is off which implies that RewriteRule directive is forbidden" occured in my Apache logfile and the visitor was displayed an error 403 forbidden error page when trying to access a cgi-script written in Perl. The solution was to add the following for the directory in question to my Apache configuration file: 

<Directory /var/www/cgi-bin>
  <Files ~ (\.pl)>
  Options ExecCGI FollowSymLinks
  </Files>
  Options +FollowSymLinks +SymLinksIfOwnerMatch
</Directory>

 

Stefan Helander

Err 310 ERR_TOO_MANY_REDIRECTS in Chrome and Firefox using Apache’s mod_rewrite

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I used Apache’s mod_rewrite in order to direct a couple of domains pointing to the same website using the 301 moved permanently (to avoid duplicate content), i.e. something like this in .htaccess: 

RewriteEngine On
RewriteCond %{HTTP_HOST} !^example\.com$
RewriteRule ^(.*)$ http://example.com/$1 [R=301,L]

I randomly got the error message 310 ERR_TOO_MANY_REDIRECTS when trying the different domains in both Chrome and Firefox (other browsers seemd to work). I had decided my site should be reached without "www", so http://www.example.com was redirected to http://example.com also. 

After a while of head scratching I found a couple of forgotten DNS entries. Two of them where outdated. My domain setup for example.com in DNS looked like this (sample IP-addresses): 

example.com zone:

@  IN  A  192.168.100.1
@  IN  A  192.168.100.2
@  IN  A  192.168.100.3

www  IN  A  192.168.100.1

But only 192.168.100.1 was valid and had a running web server on it.

I guess what happens is when Chrome/Firefox tries to talk to 192.168.100.2 or .3 and get no response, they add "www" in front of the domain name, i.e. http://www.example.com. Now it got a response from the webserver saying 301 redirect to http://example.com. Now trying to talk to example.com on 192.168.100.2 or .3 no response, adding "www" and there we have our loop.

Fixing the DNS entries (removed the invalid 192.168.100.2 and .3) fixed the problem. A bit odd and hard to find, and most of all stupid to have the outdated records still in the zone. 

 

Stefan Helander

Remove or add www to URL using Apache mod_rewrite

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To avoid a website being considered as "duplicate content" by Google (i.e. the same website appearing under different URLs) it is a good idea to make sure the website doesnt appear as both http://www.example.com and http://example.com. This can be achieved by using the mod_rewrite in Apache using the .htaccess file.

To remove "www" from the URL, i.e. the website’s URL should be http://example.com, your .htaccess should look like this: 

RewriteEngine On
RewriteCond %{HTTP_HOST} !^example\.com$
RewriteRule ^(.*)$ http://example.com/$1 [R=301,L]

If you instead want to make sure "www" is added, i.e. the website’s URL should be http://www.example.com, your .htaccess should look like this: 

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.example\.com$
RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]

 

Stefan Helander

TYPO3 cms installation fails in step 2

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If you are installing the TYPO3 content management system (CMS), after uploading the files to your web server and setting some directory permissions, you are supposed to point your browser to your web server’s root where you just have installed TYPO3 in order to continue the installation. A screen similar to this is displayed:

TYPO3 installation step 1

Click to enlarge

Enter database username, password and server (normally “localhost”) and click continue. If the following screen (as step 2) is displayed, you are in trouble:

TYPO3 installation step 2

Click to enlarge

This screen is supposed to show you the availible databases for selection. But as you can see it ends just below the word “Database”. No error message is displayed.

The reason for this is that PHP is running in Safe mode. By configuring your webserver/PHP to run with Safe mode off the installation will work.

This situation is actually described in the TYPO3 Wiki under troubleshooting saying “This could cause the Install Tool to display an error message”. In my case it didn’t and it took some time of head scratching to figure it out.