Everything is Linux

Thursday, August 14, 2014

Recovering Ubuntu after loading windows in dual booting environment

How to recover Ubuntu 10 after installing windows in dual booting environment?

How to recover Ubuntu 10 after installing windows in dual booting environment?

Machine with 2 disks and Ubnutu 10 and Windows xp installed in second disk /dev/sdb. Due to some problem in Windows, reinstalled the windows XP. After re-installation, ubuntu grub is over writen by windows and only windows is booting.
Procedure to recover:
1. Boot through Ubnutu Live CD
2. Type $ sudo fdisk -l to confirm the disk availbility.
3. Here Ubuntu is installed in /dev/sdb7 which is / partition and /dev/sdb8 is swap and /dev/sdb1 is windows partition.
4. For modifying Grub, root partition to be mounted first.
$ sudo mount /dev/sdb7 /mnt
5. For installing grub on /dev/sdb , give following command,
$ sudo grub-install --root-directory=/mnt /dev/sdb
6. Rebooted the machine. Now grub options coming for Ubnutu. But If we select windows, it gives "Insert system disk" error and was not booting.
7. Now booted in Ubnutu OS and given following command for updating grub.
$ sudo update-grub2
8. Restared the desktop now and verified both Ubnutu and windows XP booting.
9. Problem solved.

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Tuesday, August 5, 2014

SSL Certificate Signing Request

SSL Certificate Signing Request

                Ensure the openssl package is not vulnerable to Heartbleed attack. To ensure the same, check the version of openssl  package. Following are the versions which are not vulnerable,

Ø  Openssl 1.0.1g
Ø  Openssl 1.0.0 branch
Ø  Openssl 0.9.8 branch

Only  openssl 1.0.1 through 1.0.1f are vulnerable to Heartbleed attack. If server has any version between 1.0.1 and 1.0.1f, then openssl needs to be updated before generating the CSR/Key. This can be checked using following command.

# rpm –qa | grep openssl

1.        Generate Private key

# openssl genrsa -des3 -out server.key 1024

Pass phrase needed. Give the passphrase as it would be kept secret.

The generated private key looks like follows,

# cat server.key

Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,485B3C6371C9916E

2.        Generate Certificate signing request

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

Enter pass phrase for server.key:

Enter the same passphrase which we have given in point 1. 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) [GB]:IN
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 []:  Valid Email ID for which certificate to be sent

Please enter the following 'extra' attributes to be sent with your certificate request

A challenge password []:
An optional company name []:

# ls -ltr server.*

-rw-r--r-- 1 root root   963 Jun 13 20:26 server.key
-rw-r--r-- 1 root root   664 Jun 13 20:35 server.csr

3.       Then server.csr needs to be sent to Certifying authority for SSL certificate.

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