Archive for February, 2010

creating a self-signed SSL Certificate

February 28, 2010

Normal web traffic is sent unencrypted over the Internet. That is, anyone with access to the right tools can snoop all of that traffic. Obviously, this can lead to problems, especially where security and privacy is necessary, such as in credit card data and bank transactions. The Secure Socket Layer is used to encrypt the data stream between the web server and the web client (the browser).
SSL makes use of what is known as asymmetric cryptography, commonly referred to as public key cryptography (PKI). With public key cryptography, two keys are created, one public, one private. Anything encrypted with either key can only be decrypted with its corresponding key. Thus if a message or data stream were encrypted with the server’s private key, it can be decrypted only using its corresponding public key, ensuring that the data only could have come from the server.

Step 1: Generate a Private Key

The openssl toolkit is used to generate an RSA Private Key and CSR (Certificate Signing Request). It can also be used to generate self-signed certificates which can be used for testing purposes or internal usage.

The first step is to create your RSA Private Key. This key is a 1024 bit RSA key which is encrypted using Triple-DES and stored in a PEM format so that it is readable as ASCII text.

openssl genrsa -des3 -out server.key 1024

Generating RSA private key, 1024 bit long modulus
e is 65537 (0x10001)
Enter PEM pass phrase:
Verifying password – Enter PEM pass phrase:

Step 2: Generate a CSR (Certificate Signing Request)

Once the private key is generated a Certificate Signing Request can be generated. The CSR is then used in one of two ways. Ideally, the CSR will be sent to a Certificate Authority, such as Thawte or Verisign who will verify the identity of the requestor and issue a signed certificate. The second option is to self-sign the CSR, which will be demonstrated in the next section.

During the generation of the CSR, you will be prompted for several pieces of information. These are the X.509 attributes of the certificate. One of the prompts will be for “Common Name (e.g., YOUR name)”. It is important that this field be filled in with the fully qualified domain name of the server to be protected by SSL. If the website to be protected will be, then enter at this prompt. The command to generate the CSR is as follows

openssl req -new -key server.key -out server.csr

Country Name (2 letter code) [GB]:****
State or Province Name (full name) [Berkshire]:****
Locality Name (eg, city) [Newbury]:****
Organization Name (eg, company) [My Company Ltd]:****
Organizational Unit Name (eg, section) []:*****
Common Name (eg, your name or your server’s hostname) []:****
Email Address []:martin dot zahn at akadia dot ch
Please enter the following ‘extra’ attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

Step 3: Remove Passphrase from Key

One unfortunate side-effect of the pass-phrased private key is that Apache will ask for the pass-phrase each time the web server is started. Obviously this is not necessarily convenient as someone will not always be around to type in the pass-phrase, such as after a reboot or crash. mod_ssl includes the ability to use an external program in place of the built-in pass-phrase dialog, however, this is not necessarily the most secure option either. It is possible to remove the Triple-DES encryption from the key, thereby no longer needing to type in a pass-phrase. If the private key is no longer encrypted, it is critical that this file only be readable by the root user! If your system is ever compromised and a third party obtains your unencrypted private key, the corresponding certificate will need to be revoked. With that being said, use the following command to remove the pass-phrase from the key:

cp server.key
openssl rsa -in -out server.key

The newly created server.key file has no more passphrase in it.

-rw-r–r– 1 root root 745 Jun 29 12:19 server.csr
-rw-r–r– 1 root root 891 Jun 29 13:22 server.key
-rw-r–r– 1 root root 963 Jun 29 13:22

Step 4: Generating a Self-Signed Certificate

At this point you will need to generate a self-signed certificate because you either don’t plan on having your certificate signed by a CA, or you wish to test your new SSL implementation while the CA is signing your certificate. This temporary certificate will generate an error in the client browser to the effect that the signing certificate authority is unknown and not trusted.

To generate a temporary certificate which is good for 365 days, issue the following command:

openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt
Signature ok
subject=/C=CH/ST=Bern/L=Oberdiessbach/O=Akadia AG/OU=Information
Technology/ dot zahn at akadia dot ch
Getting Private key

Step 5: Installing the Private Key and Certificate

When Apache with mod_ssl is installed, it creates several directories in the Apache config directory. The location of this directory will differ depending on how Apache was compiled.

cp server.crt /usr/local/apache/conf/ssl.crt
cp server.key /usr/local/apache/conf/ssl.key

Step 6: Configuring SSL Enabled Virtual Hosts

SSLEngine on
SSLCertificateFile /usr/local/apache/conf/ssl.crt/server.crt
SSLCertificateKeyFile /usr/local/apache/conf/ssl.key/server.key
SetEnvIf User-Agent “.*MSIE.*” nokeepalive ssl-unclean-shutdown
CustomLog logs/ssl_request_log \
“%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \”%r\” %b”

Step 7: Restart Apache and Test

/etc/init.d/httpd stop
/etc/init.d/httpd stop

True Indeed !!

February 22, 2010

Only a life lived for others is a life worthwhile!!

Live as if you were to die tomorrow
Learn as if you were to live forever…

Life is only a reflection of what we allow ourselves to see

I know next year will be my time
to become more independent
.. But I am just not ready!!

Do not count what you have lost
Just see what you have now
because past never comes back
but sometimes future can give us
back our lost things!!

Silence is one of the hardest arguments to refute

If you love something let it go
If it come back to you it’s your
If it doesn’t, it never was!!

The true test of character is not
how much we know how to do, but
how we behave when we don’t
know what to do!!

For every moment a memory is created
make every moment a good one

Life is like a rainbow you need
both the sun and the rain to make
its colors appear!

Happiness is like a butterfly
the more you chase it
the more it will elude you
But if you turn your attention to other things
it will come and sit softly on your shoulder!!

Take time to deliberate; but when the time for action arrives, stop thinking and go in!!

“Yesterday is a canceled check; tomorrow is a promissory note; today is the only cash you have – so spend it wisely”

There is a time for departure even when there’s no certain place to go.

Better late than never, but never late is better.

For everything there is a season,
And a time for every matter under heaven:
A time to be born, and a time to die;
A time to plant, and a time to pluck up what is planted;
A time to kill, and a time to heal;
A time to break down, and a time to build up;
A time to weep, and a time to laugh;
A time to mourn, and a time to dance;
A time to throw away stones, and a time to gather stones together;
A time to embrace, And a time to refrain from embracing;
A time to seek, and a time to lose;
A time to keep, and a time to throw away;
A time to tear, and a time to sew;
A time to keep silence, and a time to speak;
A time to love, and a time to hate,
A time for war, and a time for peace.

Edit a file when viewing with less / more !!

February 16, 2010

I use less or more pagers to view a file. How do I start an editor (such as vi or other text editor) to edit the current file without leaving the less or more pager command.

Here is the trick –
You define your EDITOR first, enter:

export EDITOR=vim
echo ‘export EDITOR=vim’ >> ~/.bash_profile

Now open any file using more or less pager:
less myfile.txt
more ~/some.conf

Now, to edit a file, hit v key from keyboard. This will start up an editor at current line and file. make changes then save and exit, you will be back with less/more pager again 🙂

localhost as a smart SMTP relay

February 2, 2010

You have a production server which is not configured to relay mails externally, but there is a application running in that server which mails its log to the given email address regarding its status and incase of any service failures. since the sendmail runs locally on localhost.localdomain name it tries to forward the mail with root@localhost.localdomain to the remote smtp server, which would get rejected because of the reason that localhost.localdomain resolves to Invalid IP. So in order to overcome that we have to rewrite the from address of root@localhost.localdomain to so that the other smtp server relays the mail from to the or whatever address you want to send the service status mail to.


Check for installed sendmail packages –

apt-get install sendmail-base sendmail-bin sendmail-cf sendmail


First add the remote server ip address and its domain name to the /etc/hosts

vi /etc/hosts

You don’t have to do the above step if your local dns can resolve the domain name to the ip address of the smtp server which is configured to relay mail.


Edit the Sendmail configuration file for forwarding mails

vi /etc/mail/

EXPOSED_USER(root uucp)dnl # users exempt from masquerading
dnl # Masquerading options
FEATURE(`nullclient’, smtpservername)dnl



run the ‘make’ command on /etc/mail directory then reload the sendmail server
/etc/init.d/sendmail reload

Finally, test your settings –
telnet localhost 25
Connected to localhost.
Escape character is ‘^]’.
220 ESMTP Sendmail 8.14.3/8.14.3/Debian-5; Tue, 2 Feb 2010 13:41:34 +0600; (No UCE/UBE) logging access from: localhost(OK)-localhost []
helo smtp
250 Hello localhost [], pleased to meet you
250 2.1.0… Sender ok
250 2.1.5… Recipient ok
354 Enter mail, end with “.” on a line by itself
hello from example1
250 2.0.0 o127fY1s008960 Message accepted for delivery
[type quit to exit].