Thursday, August 30, 2012

Apache Virtualhost URL Rewrite - Keys to Success

Have you ever tried to make Apache URL Rewrite to work at the Virtualhost level and felt like you are banging your head on the wall, don't think you are alone, I am with you.
After lots and lots of search,  read through documentation, trial and error, I  finally got it to work. This configuration will work with a Reverse Proxy Server in the front.  Also if Apache & Reverse Proxy Servers are listening in different port (Example Reverse Proxy on port 80 and Apache on port 8080), use the Apache listening port on your VirtualHost configuration.

Always start with  "Apache -S" (In some cases httpd -S) option. This will list all the issues found in httpd.conf file. Actually I found couple of issues with my httpd.conf file, in fact Apache was up and running with those issues and driving me crazy.

For the Jump Start just copy paste the following lines into to your https.conf file and JUST change the domain name.

NameVirtualHost *:80
<VirtualHost *:80>
DocumentRoot "c:\www\"
# Following two lines are handy for debugging, but don't do it on your production machine
RewriteLog "C:\www\temp\rewrite.log"
RewriteLogLevel 9
RewriteEngine on
# Put all your ReWrite rules over here for
RewriteRule index.html$ welcome.html [NC,L]
<VirtualHost *:80>
DocumentRoot "c:\www\"
RewriteEngine on
# Put all your ReWrite rules over here for
RewriteRule index.html$ welcome.html [NC,L]

Now lets talk about all the mistakes you can do (To be precise I did)

Mistake #0:
Trying to debug without running "Apache -S" (In some cases httpd -S) command. You must resolve all the issues listed by that command, before you start think about why is not working.

Mistake #1:
<VirtualHost *:80> element alone is not sufficient to trigger URL Rewrite and you need NameVirtualHost *:80 prior to that.

Mistake #2:
NameVirtualHost is incorrect. Just go with *:80

Mistake #3:
What ever you put in after NameVirtualHost should be exactly repeated in every VirtualHost element.
Each server should be specified in ServerName attribute and not in VirtualHost
For example

NameVirtualHost *:80


is incorrect.
Correct way to do it is

NameVirtualHost *:80
<VirtualHost *:80>

<VirtualHost *:80>

Mistake #4:
No port to be specified in the ServerName
For example

<VirtualHost *:80>
is incorrect.

Right one is

<VirtualHost *:80>

Mistake #5:
All VirtualHost element must have at least ServerName  & DocumentRoot in it. I will add "ReWriteEngine On" to that.

For Example

RewriteEngine on  # Globally Turning it on has no impact on VirtualHost

<VirtualHost *:80>
DocumentRoot "c:\www\"
RewriteRule index.html$ welcome.html [NC,L]

won't do any URL ReWrite.
Instead you must put that in inside the VirtualHost

<VirtualHost *:80>
DocumentRoot "c:\www\"
RewriteEngine on  # You need it here.
RewriteRule index.html$ welcome.html [NC,L]

Mistake #6:
This may sound sillly, but I am sure someone will do it.
Putting  "."(dot) instead of ":" (colon) between * and 80.
*.80 is incorrect
*:80 is correct.
This may happen especially if you use IP address instead of star.

Still reading my blog, ok then, let me drive you crazy.
Lets talk about Apache listening on multiple ports and settingup VirtualHosts.

Lets say your Apache is listening on Port 80 as well as 8080 and want to setup Virtual host.
Here is the right way to do it.

NameVirtualHost *:80
NameVirtualHost *:8080

<VirtualHost *:80 *:8080>
DocumentRoot "c:\www\"
RewriteEngine on  # You need it here.
RewriteRule index.html$ welcome.html [NC,L]

NameVirtualHost *:80 *:8080  #  IS INCORRECT

Well it took two days for me solve this problem. I would really appreciate if you drop a comment, whether it was helpful solving your problem or not. Especially if you can mention the Mistake # that would be great, of course you can be anonymous.

Friday, August 24, 2012

CheatSheet for Apache & Regular Expression ...

I happened to stumble on this site while trying to figure out Apache Mod_Rewrite to work.
This site has Cheet Sheets for Apache, Regular Expressions, CSS, Javascript , you name it, he got it.

Thank you Dave.

Tuesday, August 21, 2012

#AlertBot -Didn't you learn your lessons

Didn't your learn your lessons from the past "test" email you have sent to all your customers. You may be great at monitoring Website. You better Monitor your email as well.
On Aug 14, I got a marketing email with subject "Test".

I got one more today (Aug 21st) with the right subject but for the event already occurred on Aug 14th?
This is the first time I am getting an invitation one week after event :)

Tuesday, August 14, 2012

Creating shortcut for a network folder in Mac

*** Read my Update 2 at the bottom of this post for a quick solution. ***

Being Windows User for a long time, it was always easy to create a short cut in Windows using "Ctrl" + "Shift" drag of a folder to Desktop. ("Ctrl" Drag folder Copies the Folder and "Shift" drag moves the folder, in case if you don't know).
In Mac if you drag a folder to Desktop it copies it and if you hold "Apple" key while dragging it moves it. Other way to create a shortcut is to right click and choose "Make Alias". It creates the shortcut in the same folder and then you can move it to the right place.

However if you want to create a shortcut for a network share, for example smb://server_name/shared_folder it was impossible because you may not have right access at smb://server_name level. I found a trick to create a shortcut for network folder using "ln" command. For those of you who don't know, when you access a network share using smb://server/folder, mac automatically mount it under /Volumes/folder(Note: No server name over here). Just open up terminal window and switch to Desktop folder.
Just type this magic command to create a shortcut
$ ln -s /Volumes/<network_folder_name> <Your Shortcut Name>
PS: "ln" stands for link and "ln -s" is for creating "Symbolic Link", fancy name for shortcut in Unix world.

Update1: Found one more option through Google. You can have Mac place the shortcut for all connected Servers in Desktop by checking the option "Connected Serveres" from Finder Preference option. However this will create the link for the Server and not the specific folder you are interested in.
Update 2: Actually if you hold "Command/Apple" + "Option" key while dragging folder to the desktop it creates the shortcut. Just drag the folder to the Desktop while holding the above two keys from /Volumes/folder_name location.

Thursday, August 9, 2012

Customizing Tomcat access log

By default Tomcat logs every web request it receives in $TOMCAT_HOME/logs folder in a file called  "localhost_access_log<Date>.txt" and it does creates one log file for every day.
By default it captures the request IP address, time of the request, bytes sent, status of request etc.
If you want to change it, for example let say you are using an reverse proxy server and wants to log the actual client IP address present in "X-Forwarded-For" then you need to specify the same in $TOMCAT_HOME/config/server.xml file.

Look for the Valve element and additional parameters you want to capture to the pattern element. You can as well configure log file name, location over here.

        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
               prefix="localhost_access_log." suffix=".txt"
               pattern="%a %{X-Forwarded-For}i %T %t  %s %b" />

For more configuration options refer to Tomcat Documentation.

For your quick reference(From Apache Documentation mentioned above).

Values for the pattern attribute are made up of literal text strings, combined with pattern identifiers prefixed by the "%" character to cause replacement by the corresponding variable value from the current request and response. The following pattern codes are supported:
  • %a - Remote IP address
  • %A - Local IP address
  • %b - Bytes sent, excluding HTTP headers, or '-' if zero
  • %B - Bytes sent, excluding HTTP headers
  • %h - Remote host name (or IP address if enableLookups for the connector is false)
  • %H - Request protocol
  • %l - Remote logical username from identd (always returns '-')
  • %m - Request method (GET, POST, etc.)
  • %p - Local port on which this request was received
  • %q - Query string (prepended with a '?' if it exists)
  • %r - First line of the request (method and request URI)
  • %s - HTTP status code of the response
  • %S - User session ID
  • %t - Date and time, in Common Log Format
  • %u - Remote user that was authenticated (if any), else '-'
  • %U - Requested URL path
  • %v - Local server name
  • %D - Time taken to process the request, in millis
  • %T - Time taken to process the request, in seconds
  • %I - Current request thread name (can compare later with stacktraces)
There is also support to write information incoming or outgoing headers, cookies, session or request attributes and special timestamp formats. It is modeled after the Apache HTTP Serverlog configuration syntax:
  • %{xxx}i for incoming headers
  • %{xxx}o for outgoing response headers
  • %{xxx}c for a specific cookie
  • %{xxx}r xxx is an attribute in the ServletRequest
  • %{xxx}s xxx is an attribute in the HttpSession
  • %{xxx}t xxx is an enhanced SimpleDateFormat pattern

Sunday, August 5, 2012

Apex Listener - Connecting to multiple databases

Warning: This will become obsolete when Kris Rice releases Apex Listener 2.0. Already Apex Listener EA1 is out.

I have already blogged about Installing Apex Listener on Tomcat and Managing Apex Listener.

If you have already installed Apex Listener 1.1 or temporarily want to connect to multiple databases then you can follow the steps.

1. Decide on the deployment name. Default one is /apex/. Select another one like /testdb/. Once you decide on the deployment name, goto <Tomcat Home>/webapps folder on your PC/Linux VM etc. and copy apex.war to testdb.war.

2. Configure the new Database Connection by accessing http://localhost:8080/testdb/listenerConfigure
Tomcat will automatically extract testdb.war content and will create testdb folder inside webapps.
Then it will give you a surprise and will say
"The APEX Listener is already configured. Please login as Administrator to access APEX Listener Administration." Let's fix it.

3. Open up <Tomcat Home>/webapps/testdb/WEB-INF/web.xml and configure "config.dir" as follows.

<param-value><Your Tomcat Home>/webapps/testdb</param-value>
Use the full path of your Tomcat Home and never tried relative path. testdb is your deployment folder.

4. Now restart your Tomcat and access the following URL to configure to your new database instance.
http://localhost:8080/testdb/listenerConfigure. Once deployed you can access your database applications using http://localhost:8080/testdb/f?p=<app>:<page>

PS: After deploying 4 or 5 apex war files I started to get "OutOfMemory" exception in TomCat. I have put in the following code in Tomcat (Present under <tomcat Home>/bin folder) to address the issue temporarily. Please post a comment if you have better fix.

# To avoid Out of Memory error
export JVM_ARGS="-Xmx1024m -XX:MaxPermSize=256m";
export CATALINA_OPTS="-Xms1024m -Xmx1024m -XX:PermSize=128m -XX:MaxPermSize=512m";

Thursday, August 2, 2012

Lost VSS Admin Password. No Problem

It's not new in IT environment, hearing from VSS Admin, Oops I don't remember the Admin password or I thought you guys migrated to Github etc., Well if that doesn't happened to you you are lucky, in my case I am not. I wanted to add some useres but couldn't be able to do it because no one knows the Admin Password. I was the only one using VSS, however it doesn't ask for the password since the VSS user name is same as my network user account. I thought I can try the same for Admin as well.
So I created account called "Admin" (Not Administrator) on my local machine, no special privilege is required. I had a local VSS client installed on my server. I went there and launched "SSADMIN.EXE" as my localhost\Admin user. You just need to "Shift" + Right Click on the file and select "Run as different User".  It automatically connected to my local VSS as Admin without asking for password. From there I have connected to my actual network VSS database(From Users-> Open Source Database) . It asked for my network user account to connect to the share since I was running it as localhost Admin. As soon as I entered my network credentials, I have connected to my network VSS database (For which I don't have the Admin password, to be precise,  our VSS admin memory block that stored the password got corrupted).
That's it I have added new Useres, granted full access to me and did everything except changing the Admin password, because it was asking for the old password. But who cares, I got what I want and if necessary, I will use the same hack one more time.

PS: This will work only when you have "Use network name for automatic login" checked.

Tag: Recover VSS Admin Password, Lost VSS Admin Password, Reset VSS Admin Password

Wednesday, August 1, 2012

Dealing with Files present in network share from SQL Developer

I have recently switched to Mac from PC and wish I could have had Mac version of TOAD. I have used TOAD for about 10 years and switching to SQL Developer is hard for me. One of the problem that I had with SQL Developer was accessing files present in the network share. Unfortunately you can't open file from SQL Developer using smb://share_name/folder syntax. I was so lucky to meet with Kris Rice @krisrice (Oh yah, the developer of SQL Developer) in ODTUG #kscope12 conference. He showed me how to do it. Looks like Mac automatically mounts the folders you access using smb://network_share under /Volumes/network_share. You just need to browse to this location and can start accessing your network share as a local drive.
Thanks Kris for this Tip.