Connect to Oracle Linux O/S without password !!

DISCLAIMER : Do not attempt this on critical or Production System.

I run multiple VirtualBox hosting Oracle Linux with Oracle database. It’s like a playground for me to do lot of oracle stuff.

Every time I have to take a connection , It’s painful to enter id/pwd for these so called playground system.

Started doing a little search as to how other fellow DBAs are getting away with this issue. Here is a little cheat trick that can be applied on non-critical systems.

Putty doesn’t give you an option to store password, but it does give you an option to store user name. Refer to below screenshot.

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Assuming user ‘neeraj’ was already created in Oracle Linux O/S , let take a connection by specifying password

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Let’s create a dir .ssh into /home/neeraj

Next challenge is how to avoid entering password everytime a connection is established to OL ( Oracle Linux ) via account ‘neeraj’

Here is a little cheat trick

Download Putty Keygen software from this url andopen the same. Keep settings as show below.

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Click on generate button and randomly move mouse on blank area to generate a random key. Within a min, you would see similar to this

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Click “Save Private Key button” and save Private key on local drive.

Note : If anyone get hold of this Private key, they can access your Virtual Machine running within VirtualBox without the need to enter id/pwd.

Next step is to open saved Private key ( C:\Misc_Things\test.ppk ) in notepad and copy the lines that represent PUBLIC key in clipboard

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Since there are 3 lines , make sure to combine all line and create sort of single line which represents Public Key.

Since your putty session via ‘neeraj’ account is still active , go into following dir /home/neeraj/.ssh/

and create a file called authorized_keys and paste that 1 line which represents public key

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Notice we have to insert ” ssh-rsa ” in front of our public key. There is a space in front and end of keyword ssh-rsa. Click on above screenshot to see a large image file

Now configure existing putty connection to use Private Key as shown below

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Now take a fresh connection …. Voilla as seen in below screenshot , we dint had to enter pwd , it utilized Private/Public key and authenticated our dummy account ‘neeraj’

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How to find Virtual Box Guest Addition version in Oracle Linux

Hi,

Recently I broke VirtualBox Guest Addition within my OracleLinux box and was not sure what version am I really running.

Here goes a simple command to check version

[root@pr ~]# modinfo vboxguest

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Running GUI via putty

April 24, 2013 1 comment

At times we have to invoke some sort of gui client ( let’s say Oracle Installer etc ) from putty. It can be a pain to have it started, but if things are configured properly it’s not that difficuilt.

For this exercise, we would require following software

1) Putty

A free open source based terminal emulator through which you can connect to your unix, linux box

You can download it from here for free

 

2) Xming X Server for Windows ( To be installed on local machine )

Again this is also based on open source , it’s a leading X Server for windows. You can download it from here for free

Configuring Xming Server

After you are done with Xming Server installation on your Win ( Win 7 in my case ) , we need to configure it by invoking Xlaunch from Xming Menu.

Here are some of the screenshots that shows you how to configure the Xming

 

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Hit Save Configuration button & then Finish

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Configuring Putty Client for Xming

Now we need to configure putty, assuming you already know your Unix/Linux Server hostname or ip address, here are the steps to configure Xming

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Change the value for scrollback to a desired bigger no.

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Make sure “Enabling X Forwarding is selected” with a value of localhost:0

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Now go back to sessions option that appear on left and save this putty configuration

Now we just need to invoke Xming Server from Start Menu.

Go to Start Menu — > All Programs –>Xming —> Xming

This will bring Xming in taskbar next to windows clock

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Take a connection through putty to your linux/Unix Server and after entering credentials type in xclock. It should come up like shown below

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If you want to run xclock in the background, invoke following command

xclock &

instead of just

xclock

So far this works great, but what i observed was as soon as shifted to oracle user on unix it stopped working it gave me this error

[oracle@pr ~]$ xclock
Xlib: connection to “localhost:11.0″ refused by server
Xlib: PuTTY X11 proxy: MIT-MAGIC-COOKIE-1 data did not match
Error: Can’t open display: localhost:11.0
[oracle@pr ~]$

For this there is a workaround, hift back to root account and issue following command

xauth list

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You might see just 1 line depending upon how many keys are present in xauth. In my case there are 3 keys

Copy the last line into clipboard

pr.localhosts.localdomain/unix:11  MIT-MAGIC-COOKIE-1  51da8af273156d606b3080213fae200d

 

Switch to Oracle account via su – oracle

and issue following command

xauth add pr.localhosts.localdomain/unix:11  MIT-MAGIC-COOKIE-1  51da8af273156d606b3080213fae200d

Basically i added key to xauth

and now you are all set and you wont get this error atleast in current session

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Oracle Recyclebin

Oracle recyclebin works pretty much works same like windows recyclebin. Concept was introduced by Oracle in 10g. It’s a pretty useful feature .. let’s say in a situation where you have dropped a table and you want to restore that table without performing db recovery.

You can check if Recyclebin is enabled or not by checking following parameter

SQL> show parameter recyclebin;

Let’s see how it works by creating a dummy user and granting him role to connect

SQL> create user john identified by john;
SQL> grant connect, resource to john;

Below is the list of tables that you can use to query information about recyclebin

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If you are connected via john and you dropped something, then you can query user_recyclebin.

Check if something is there in recyclebin or not

select * from user_recyclebin;

Let’s create a table,, insert few records into it.

SQL> create table john.sales ( versioninfo varchar(30), insertdate date);

SQL> insert into john.sales values (‘v1′, sysdate);

SQL> commit;

Now let’s drop the table ..

SQL> drop table john.sales ;

Above statement will drop the table, behind the scenes, it’s just renaming the table sales and putting it in recyclebin. Above statement doesn’t release the space occupied by Table.

Let’s query our recyclebin and see what is sitting there now.

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As we saw in above screenshot, object just got renamed to BIN$something.

If you want to permanent delete this table from recyclebin then just issue following SQL Statement

SQL > purge recyclebin;

However, If we want to restore it back from recyclebin, all we have to do it issue following sql statement.

SQL> flashback table john.sales to before drop;

What if, if you would prefer not to send table into recyclebin at the 1st place & delete it permanently. You can issue following SQL statement

SQL> drop table john.sales purge ;

What if, … if i create table sales, then drop it , again create table sales, and then again drop it and repeat this for let’s say 10 times . It will obviously show 10 records in recyclebin starting with BIN$, if you issue SQL command

SQL> flashback table john.sales to before drop;

It would restore the table based on LIFO ( Last In first Out ), however if you want to restore specific version, you can issue following command

SQL> flashback table john.”BIN$2te9VmGlINrgQKjArjhl3A==$0” to before drop;

 

Replace BIN with the version that you would want to restore.

 

 

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Oracle Forum is due for upgrade in April 2013 …

April 19, 2013 1 comment
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Display full path of working directory within the command prompt – OEL

Was traversing through Oracle Enterprise Linux file structure and realized that by default it doesn’t show me what dir I am sitting in unless and until I execute ‘pwd’ command

To display DIR info. at Linux prompt , I just added the following to the systemwide configuration file /etc/bashrc:
 
 Code:
  # customized prompt with full path of working dir

PS1=”[\u@\h \w]\\$ “

 

 

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How to enable ftp on VirtualBox

You can transfer file from your local machine to virtual box via shared folders or via ftp.

By default looks like ftp is blocked on Virtual Box

Just inside your guest O/S i.e. VirtualBox Linux go to

/etc/xinetd.d/

and modify gssftp file

Change from ‘Yes’ to ‘No’ for DISABLE column as shown in below screenshot and remove value against “server_args”

ftp

 

 

 

 

 

You can restart ftp service via following command

/etc/init.d/xinetd restart

 

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