Apache

References

• Apache Documentation (a bit fuzzy...)
  • mod_rewrite
• Apache HTTP Server Wiki (much clearer but incomplete)

Enabling .htaccess files

In case the .htaccess files are ignored (see [1]):

Stop! Don't use htaccess files for mod_rewrite unless you have no other choice. Doing so is slow and confusing.

1. Put a nonsense line (such as Wooga) in your htaccess file and try the request again. If you don't see a 500 Internal Server Error message, your htaccess file is being ignored altogether. The solution is to set both AllowOverride FileInfo and Options FollowSymlinks in httpd.conf (on Ubuntu, check apache2/sites-enabled/000-default, or add your own config file in apache2/conf.d) for the directory in question.

DocumentRoot /var/www
<Directory />
    Options FollowSymLinks
    AllowOverride FileInfo          # Must *NOT* be ''none''
</Directory>

2. If you think your rules look ok but you still see a 500 Internal Server Error message, make sure mod_rewrite is loaded in the server.
3. If you have ensured that mod_rewrite is loaded, and that RewriteRule is enabled for htaccess files, it could be that your rules are looping.
4. If none of the above steps help, try a very simple rewrite to check if the module is enabled. For example:

RewriteEngine On
# Redirect all requests to example.com
RewriteRule ^ http://example.com/

Rewrite Rules

• References: [2], [3]
• Rewrite rules are either defined in virtual host configuration (i.e. httpd.conf or similar) or in the .htaccess file, per directory (but this is discouraged — I don't know why exactly, slower...}}

Enable Rewrite module

Simply type:

a2enmod rewrite
service apache2 restart

Why they can't simply say so in apache doc is just a mistery.

Frequent errors

• Make sure that all files in your /var/www (or any other relevant directory) are owned by www:www-data (if not, rule conditions like RewriteCond %{REQUEST_FILENAME} -f may fail!)

sudo chown -R www:www-data /var/www

• If you changed apache config, make sure that you restarted the server

sudo /etc/init.d/apache2 restart

• If you use mod_rewrite in .htaccess files, make sure that these files are indeed read by Apache (see section above).
• Enable rewrite log to ease debugging. Add a file /etc/apache2/conf.d/rewritelog.conf:

RewriteLog "/var/log/apache2/rewrite.log"
RewriteLogLevel 8                              # Max 9

Some example of rewrite rules

See [4] for more examples, and what-not.

Rewrite URL for missing resource

From [5], rewrite URL for missing resource.

# For each web request (file or directory) that doesn't start with /en-US/, 
# serve up the original resource if it exists, otherwise serve up the /en-US/ version.
RewriteCond $0 !^en-US/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule .+ en-US/$0 [L]

Rewrite URL for missing resources (advanced)

# Try to replace query for non-existing images to white/black images
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} -f       # true if file exists
RewriteRule (.*) - [L]                   # Applied if condition above is true, [L] means LAST rule

# 10-0- up to 10-511-
RewriteCond %{REQUEST_URI} /10-[0-9]+-([0-9]|[1-9][0-9]|[1-4][0-9][0-9]|50[0-9]|51[0-1])\.png
RewriteRule (.*) white.png [L]

# 9-0- up to 9-255-
RewriteCond %{REQUEST_URI} /9-[0-9]+-([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.png
RewriteRule (.*) white.png [L]

# 8-0- up to 8-127-
RewriteCond %{REQUEST_URI} /8-[0-9]+-([0-9]|[1-9][0-9]|1[01][0-9]|12[0-7])\.png
RewriteRule (.*) white.png [L]

# 7-0- up to 7-63-
RewriteCond %{REQUEST_URI} /7-[0-9]+-([0-9]|[0-5][0-9]|6[0123])\.png
RewriteRule (.*) white.png [L]

# 6-0- up to 6-31-
RewriteCond %{REQUEST_URI} /6-[0-9]+-([0-9]|[0-2][0-9]|3[01])\.png
RewriteRule (.*) white.png [L]

# 5-0- up to 5-15-
RewriteCond %{REQUEST_URI} /5-[0-9]+-([0-9]|1[0-5])\.png
RewriteRule (.*) white.png [L]

# 4-0- up to 4-7-
RewriteCond %{REQUEST_URI} /4-[0-9]+-([0-7])\.png
RewriteRule (.*) white.png [L]

# 3-0- up to 3-3-
RewriteCond %{REQUEST_URI} /3-[0-9]+-([0-3])\.png
RewriteRule (.*) white.png [L]

# 2-0- up to 2-1-
RewriteCond %{REQUEST_URI} /2-[0-9]+-([0-1])\.png
RewriteRule (.*) white.png [L]

# 1-0- up to 1-1-
RewriteCond %{REQUEST_URI} /1-[0-9]+-0\.png
RewriteRule (.*) white.png [L]

RewriteRule (.*) black.png [L]

Tags

DirectoryIndex

• Use DirectoryIndex to change list of default name of index file while browsing directory

DirectoryIndex index.php index.html         # Will serve php version first
DirectoryIndex mycustomindex.html           # To point to specific file when browsing directory (no directory listing)

HTTPS

From [6]. Assumptions:

• Already a website present at /var/www
• Package ssl-cert installed (that create snakeoil (i.e. self-signed) certificates in /etc/ssl)

# Load and enable SSL module
sudo a2enmod ssl
sudo /etc/init.d/apache2 force-reload

# Edit file
sudo vim /etc/apache2/sites-available/default-ssl
# ... and change lines as follows (for key/cert we use the snakeoil ones):
#  SSLEngine on
#  SSLOptions +FakeBasicAuth +ExportCertData +StrictRequire

#Enable the default SSL site:
sudo a2ensite default-ssl

# Tell Apache to reload its configuration:
sudo /etc/init.d/apache2 reload

To also add user authentication, add the following lines to either

• File .htaccess in website directory
• Section <Location /> in /etc/apache2/sites-available/default-ssl:

Do not use a Directory tag, it does not work [7], [8].

Also, make suure that password file is not in the html subtree (i.e. can't be downloaded by clients).

<Location "/">
  AuthType Basic
  AuthName "default"
  AuthUserFile /var/www/etc/filename.ssl.passwd
  Require valid-user
</Location>

Then create the password file with the command htpasswd

htpasswd -c -s /var/www/etc/filename.ssl.passwd username          # set password, using SHA-1
sudo chown www-data:www-data /var/www/etc/filename.ssl.passwd     # set permission (or get 500 - Internal server error)

Finally, reload apache2:

sudo /etc/init.d/apache2 reload

In case of problem, check log file /var/log/apache2/error.log.

Parse and generate new certificates

The server private key is located at /etc/ssl/private/ssl-cert-snakeoil.key and the self-signed certificate at /etc/ssl/certs/ssl-cert-snakeoil.key.

To parse the current private key:

sudo openssl rsa -noout -text -in /etc/ssl/private/ssl-cert-snakeoil.key      # Show coefficient of private key
sudo openssl rsa -noout -modulus -in /etc/ssl/private/ssl-cert-snakeoil.key   # Show private key modulus

To parse the current self-signed certificate:

openssl asn1parse -in /etc/ssl/certs/ssl-cert-snakeoil.pem                    # Show certificate fields

This produces for instance:

 openssl asn1parse -in /etc/ssl/certs/ssl-cert-snakeoil.pem
    0:d=0  hl=4 l= 698 cons: SEQUENCE          
    4:d=1  hl=4 l= 418 cons: SEQUENCE          
    8:d=2  hl=2 l=   3 cons: cont [ 0 ]        
   10:d=3  hl=2 l=   1 prim: INTEGER           :02
   13:d=2  hl=2 l=   9 prim: INTEGER           :C5E28AFC1DC8799C
   24:d=2  hl=2 l=  13 cons: SEQUENCE          
   26:d=3  hl=2 l=   9 prim: OBJECT            :sha256WithRSAEncryption
   37:d=3  hl=2 l=   0 prim: NULL              
   39:d=2  hl=2 l=  21 cons: SEQUENCE          
   41:d=3  hl=2 l=  19 cons: SET               
   43:d=4  hl=2 l=  17 cons: SEQUENCE          
   45:d=5  hl=2 l=   3 prim: OBJECT            :commonName
   50:d=5  hl=2 l=  10 prim: PRINTABLESTRING   :zavcxv0035
   62:d=2  hl=2 l=  30 cons: SEQUENCE          
   64:d=3  hl=2 l=  13 prim: UTCTIME           :150605232158Z
   79:d=3  hl=2 l=  13 prim: UTCTIME           :250602232158Z
   94:d=2  hl=2 l=  21 cons: SEQUENCE          
   96:d=3  hl=2 l=  19 cons: SET               
   98:d=4  hl=2 l=  17 cons: SEQUENCE          
  100:d=5  hl=2 l=   3 prim: OBJECT            :commonName
  105:d=5  hl=2 l=  10 prim: PRINTABLESTRING   :zavcxv0035
  117:d=2  hl=4 l= 290 cons: SEQUENCE          
  121:d=3  hl=2 l=  13 cons: SEQUENCE          
  123:d=4  hl=2 l=   9 prim: OBJECT            :rsaEncryption
  134:d=4  hl=2 l=   0 prim: NULL              
  136:d=3  hl=4 l= 271 prim: BIT STRING        
  411:d=2  hl=2 l=  13 cons: cont [ 3 ]        
  413:d=3  hl=2 l=  11 cons: SEQUENCE          
  415:d=4  hl=2 l=   9 cons: SEQUENCE          
  417:d=5  hl=2 l=   3 prim: OBJECT            :X509v3 Basic Constraints
  422:d=5  hl=2 l=   2 prim: OCTET STRING      [HEX DUMP]:3000
  426:d=1  hl=2 l=  13 cons: SEQUENCE          
  428:d=2  hl=2 l=   9 prim: OBJECT            :sha256WithRSAEncryption
  439:d=2  hl=2 l=   0 prim: NULL              
  441:d=1  hl=4 l= 257 prim: BIT STRING

• The field UTCTIME is coded as YYMMDDHHmmssZ.

To generate a new key and certificate:

openssl req -x509 -nodes -days 3652 -newkey rsa:2048 -keyout ssl-cert-$HOSTNAME.key -out ssl-cert-$HOSTNAME.pem

Typically you can leave all request fields, except the Common Name which should be set to some name, or server FQDN:

Generating a 2048 bit RSA private key
..............................................................+++
..................................+++
unable to write 'random state'
writing new private key to 'ssl-cert-zavcxl0005.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:.
State or Province Name (full name) [Some-State]:.
Locality Name (eg, city) []:.
Organization Name (eg, company) [Internet Widgits Pty Ltd]:.
Organizational Unit Name (eg, section) []:.
Common Name (e.g. server FQDN or YOUR name) []:zavcxl0005.zav.st.com
Email Address []:.

Then install the key and certificate and update /etc/apache2/default-ssl.conf:

sudo mv ssl-cert-$HOSTNAME.pem /etc/ssl/certs
sudo chmod 640 ssl-cert-$HOSTNAME.key
sudo chown root:ssl-cert ssl-cert-$HOSTNAME.key
sudo mv ssl-cert-$HOSTNAME.key /etc/ssl/private

Edit /etc/apache2/sites-available/default-ssl.conf (replacing myhostname as necessary):

-    SSLCertificateFile /etc/ssl/certs/ssl-cert-snakeoil.pem
-    SSLCertificateKeyFile /etc/ssl/private/ssl-cert-myhostname.key
+    SSLCertificateFile /etc/ssl/certs/ssl-cert-snakeoil.pem
+    SSLCertificateKeyFile /etc/ssl/private/ssl-cert-myhostname.key