Upgrade Fedora 10 packages

Recently I got to upgrade some packages of the my server which runs on Fedora 10. However I also got to know that Fedora 10 repo are not more maintained. Therefore I searched for some other repo and found a repo called remi. Using which I could upgrade my packages. Here are the steps that I followed :

rpm -Uvh http://rpms.famillecollet.com/remi-release-10.rpm
then I could update the php packages by executing following command :
yum --enablerepo=remi install php-pear php-pdo php-mysql php-pecl-memcache php-gd php-mbstring php-mcrypt php-xml

Rererence : http://www.if-not-true-then-false.com/2010/install-apache-php-on-fedora-centos-red-hat-rhel/

Generate a SSL certificate request for Multidomains

Recently I had a need to have a SSL certificate which should be used in multiple domains. When I search on that I found that it can be done using Unified Communications Certificates (UUC) :

This is how I generated a multidomain certificate request :

1. Open openssl.cnf
2. Make sure following line are there in that file :

[req]
req_extensions = v3_req

[v3_req]
subjectAltName = @alt_names

[alt_names]
DNS.1 = example.com
DNS.2 = hello.example.com
DNS.3 = testing.com


You should add your domains as given in under [alt_names]

3. Create a private key

4. generate your certificate requests by providing required information

Thats all! you are done!!!

Reference : http://playnice.ly/blog/2011/01/03/multi-domain-ucc-ssl-certificates-on-nginx-with-1-ip-address/



You can make sure by
openssl req -text -noout -in ssl.csr

Under the alternative section you can find your all the domains listed.

IPv6 over IPv4 tunneling - IPv6to4

All were talking about IPv6 day and all the gaints were participating in IPv6 Day. Therefore I also want to feel the IPv6.

I created a tunnel with Hurricane and got an IPv6 address. However inorder to get this working we need to establish a tunnel to one of the Hurricane's Server.
My OS is Fedora 10 and I did following steps to enable IPv6 and IPv6to4 Tunnelling in my PC.

(If you also want to do, just execute following 4 lines in your Terminal as super user.

echo "NETWORKING_IPV6=yes" >> /etc/sysconfig/network
echo "IPV6_DEFAULTDEV=tun6to4">> /etc/sysconfig/network
echo "IPV6INIT=yes" >> /etc/sysconfig/network-scripts/ifcfg-eth0
echo "IPV6TO4INIT=yes">> /etc/sysconfig/network-scripts/ifcfg-eth0

In addition to that I created following script :

/etc/sysconfig/network-scripts/ifcfg-sit1

and added following content,

OOTPROTO="none"
DEVICE="sit1"
IPV6INIT=yes
IPV6TUNNELIPV4=xx.xx.xx.xx
IPV6TUNNELIPV4LOCAL=yy.yy.yy.yy
IPV6ADDR="2001:xxx:x:xxx::x/64"
ONBOOT=yes

After this the tunnel was established and everything was working fine.

References :
http://fedoraproject.org/wiki/IPv6Guide
http://unix.stackexchange.com/questions/7720/how-do-i-set-up-an-ipv6-tunnel-in-fedora

Enable Tamil and Sinhala input methods

Here how I enabled Tamil (Renganathan IM) and Sinhala (Wijesekara) on Ubuntu 11.

Step 1 : As a root, do :

apt-get install ibus im-switch ibus-m17n m17n-db m17n-contrib ttf-tamil-fonts language-pack-ta-base ttf-sinhala-lklug language-pack-si-base


Step 2 : Just run from your user account (Not as root) :
rm -f ~/.xinput.d/* ; im-switch -z all_ALL -s ibus

Thereafter restart the session (Just logoff and login)

Thereafter do "ibus-setup" and configure your prefered input setup. In addition to that you can configure where it should appear in your screen.

Enjoy!

Reference : http://sinhala.sourceforge.net/

Postfix with MySQL Backend

Here I am trying to describe how I configured Postfix with MySQL backend. Here I have given only the important parameter, however you can find tune this in various ways.

1.

Configure your Postfix with MySQL support.

I used following command - make -f Makefile.init makefiles 'CCARGS=-DHAS_MYSQL -I/usr/include/mysql' 'AUXLIBS=-L/usr/lib/mysql -lmysqlclient -lz -lm'

Before do this, please make sure that you have installed all the MySQL components, including mysql-devel.

2.

Then do the make

3.

DO the make install. At the end of this phase you will be prompt with many questions, answer them appropriate.

4.

Then start configure your Postfix, normally you can find the configuration in main.cf

The important settings (though there are several settings) you need to add are :

data_directory = /var/lib/postfix
mail_owner = postfix
- make sure that you have created the user postfix
myhostname = mail.yy.xx.lk
mydomain = XX,cc.lk
myorigin = $mydomain
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost
relayhost = 192.NN.N.N
home_mailbox = Maildir/
- This is important, and this is where you say that you want to use MailDir, not Mailbox
virtual_gid_maps = static:506
virtual_mailbox_base = /var/mail/vhosts
virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf
virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf
virtual_minimum_uid = 100
virtual_transport = virtual
virtual_uid_maps = static:504
- You must create another user, may be vmail, who should have permission to write mails to maildir. After adding those user, you need to specify the uid and gid of that user here in uid_maps and gid_maps. Also make sure that you have given sufficient permission to the mailbox_base to the user that you have created.

After doing all these settings in the main.cf file, you need to create another two files that you have given in "virtual_mailbox_domains" and "virtual_mailbox_maps".

In my case etc/postfix/mysql_virtual_domains_maps.cf contains following parameters :

hosts = localhost
dbname = maildb
user = mailuser
password = xxxxxxx
table = mail_domains
select_field = mail_domain
where_field = mail_domain

This tells postfix that what are the domains should be handled by the postfix it self and what are should be routed to other MTAs.


/etc/postfix/mysql_virtual_mailbox_maps.cf contains :
hosts = localhost
dbname = maildb
user = mailuser
password = XXXX
table = mail_accounts
select_field = maildir
where_field = mail_user

This is used to select the MailDir name for the respective email account. For example if someone sends a mail to sarves@xyz.com, this will find and tells that where that message should go in the virtual_mailbox_base.

Hope this will work for you all as well.

Good luck

Reference :
http://hostingsoftware.net/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=56
http://www.postfix.org/INSTALL.html

Creating Certificate Authorities and self-signed SSL certificates

Following is a step-by-step guide to creating your own CA (Certificate Authority) -- and also self-signed SSL server certificates -- with openssl on Linux. Self-signing is the simpler route to take, but making one's own CA allows the signing of multiple server certificates using the same CA and involves only a few extra steps.

After using openssl to generate the necessary files, you'll need to integrate them into Apache. This process differs between Linux distros and versions of Apache. Additional references exist at the end of this document. My instructions for Setting up SSL: Ubuntu and Apache 2 are kept most current, and will carry you through to completion.

Making a homemade CA or self-signed certificate will cause the client web browser to prompt with a message whether to trust the certificate signing authority (yourself) permanently (store it in the browser), temporarily for that session, or to reject it. The message "web site certified by an unknown authority... accept?" may be a business liability for general public usage, although it's simple enough for the client to accept the certificate permanently.

Whichever route you take, you'll save the periodic expense of paying a recognized signing authority. This is purely for name recognition -- they've paid the major browser producers to have their CA pre-loaded into them. So if you're on a budget, have a special need or small audience, this may be useful.

Before you start
You need Apache and openssl. Compiling them from source, handling dependencies, etc. is beyond the scope of this document. You can consult their documentation, or go with a mainstream Linux distro that will do the preliminary work for you.

Now you need to decide whether you'll make a CA (Certificate Authority) and sign a server certificate with it -- or just self-sign a server certificate. Both procedures are detailed below.
(1A) Create a self-signed certificate.

Complete this section if you do NOT want to make a CA (Certificate Authority). If you want to make a CA, skip 1A entirely and go to 1B instead.

Some steps in this document require priviledged access, and you'll want to limit access to the cert files to all but the root user. So you should su to root and create a working directory that only root has read/write access to (for example: mkdir certwork, chmod 600 certwork). Go to that directory.

Generate a server key:

openssl genrsa -des3 -out server.key 4096

Then create a certificate signing request with it. This command will prompt for a series of things (country, state or province, etc.). Make sure that "Common Name (eg, YOUR name)" matches the registered fully qualified domain name of your box (or your IP address if you don't have one). I also suggest not making a challenge password at this point, since it'll just mean more typing for you.

The default values for the questions ([AU], Internet Widgits Pty Ltd, etc.) are stored here: /etc/ssl/openssl.cnf. So if you've got a large number of certificate signing requests to process you probably want to carefully edit that file where appropriate. Otherwise, just execute the command below and type what needs to be typed:

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

Now sign the certificate signing request. This example lasts 365 days:

openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

Make a version of the server.key which doesn't need a password:

openssl rsa -in server.key -out server.key.insecure
mv server.key server.key.secure
mv server.key.insecure server.key

These files are quite sensitive and should be guarded for permissions very carefully. Chown them to root, if you're not already sudo'd to root. I've found that you can chmod 000 them. That is, root will always retain effective 600 (read) rights on everything.

Now that you've just completed Step 1A, skip ahead to Step 2.

(1B) Generate your own CA (Certificate Authority).

Complete this section if you want to make a CA (Certificate Authority) and sign a server certificate with it. The steps for making a server certificate are also included here. If you'd rather one-time self-sign a server certificate, skip this step entirely and go to 1A instead.

Some steps in this document require priviledged access, and you'll want to limit access to the cert files to all but the root user. So you should su to root and create a working directory that only root has read/write access to (for example: mkdir certwork, chmod 600 certwork). Go to that directory.

In this step you'll take the place of VeriSign, Thawte, etc. You'll first build the CA key, then build the certificate itself.

The Common Name (CN) of the CA and the Server certificates must NOT match or else a naming collision will occur and you'll get errors later on. In this step, you'll provide the CA entries. In a step below, you'll provide the Server entries. In this example, I just added "CA" to the CA's CN field, to distinguish it from the Server's CN field. Use whatever schema you want, just make sure the CA and Server entries are not identical.

CA:
Common Name (CN): www.somesite.edu CA
Organization (O): Somesite
Organizational Unit (OU): Development

Server:
Common Name (CN): www.somesite.edu
Organization (O): Somesite
Organizational Unit (OU): Development

If you don't have a fully qualified domain name, you should use the IP that you'll be using to access your SSL site for Common Name (CN). But, again, make sure that something differentiates the entry of the CA's CN from the Server's CN.

openssl genrsa -des3 -out ca.key 4096
openssl req -new -x509 -days 365 -key ca.key -out ca.crt

Generate a server key and request for signing (csr).

This step creates a server key, and a request that you want it signed (the .csr file) by a Certificate Authority (the one you just created in Step #1B above.)

Think carefully when inputting a Common Name (CN) as you generate the .csr file below. This should match the DNS name, or the IP address you specify in your Apache configuration. If they don't match, client browsers will get a "domain mismatch" message when going to your https web server. If you're doing this for home use, and you don't have a static IP or DNS name, you might not even want worry about the message (but you sure will need to worry if this is a production/public server). For example, you could match it to an internal and static IP you use behind your router, so that you'll never get the "domain mismatch" message if you're accessing the computer on your home LAN, but will always get that message when accessing it elsewhere. Your call -- is your IP stable, do you want to repeat these steps every time your IP changes, do you have a DNS name, do you mainly use it inside your home or LAN, or outside?

openssl genrsa -des3 -out server.key 4096
openssl req -new -key server.key -out server.csr

Sign the certificate signing request (csr) with the self-created Certificate Authority (CA) that you made earlier.

Note that 365 days is used here. After a year you'll need to do this again.

Note also that I set the serial number of the signed server certificate to "01". Each time you do this, especially if you do this before a previously-signed certificate expires, you'll need to change the serial key to something else -- otherwise everyone who's visited your site with a cached version of your certificate will get a browser warning message to the effect that your certificate signing authority has screwed up -- they've signed a new key/request, but kept the old serial number. There are a couple ways to rectify that. crl's (certificate revocation list) is one method, but beyond the scope of the document. Another method is for all clients which have stored the CA certificate to go into their settings and delete the old one manually. But for the purposes of this document, we'll just avoid the problem. (If you're a sysadmin of a production system and your server.key is compromised, you'll certainly need to worry.)

The command below does a number of things. It takes your signing request (csr) and makes a one-year valid signed server certificate (crt) out of it. In doing so, we need to tell it which Certificate Authority (CA) to use, which CA key to use, and which Server key to sign. We set the serial number to 01, and output the signed key in the file named server.crt. If you do this again after people have visited your site and trusted your CA (storing it in their browser), you might want to use 02 for the next serial number, and so on. You might create some scheme to make the serial number more "official" in appearance or makeup but keep in mind that it is fully exposed to the public in their web browsers, so it offers no additional security in itself.

openssl x509 -req -days 365 -in server.csr -CA ca.crt -CAkey ca.key -set_serial 01 -out server.crt

To examine the components if you're curious:

openssl rsa -noout -text -in server.key
openssl req -noout -text -in server.csr
openssl rsa -noout -text -in ca.key
openssl x509 -noout -text -in ca.crt

Make a server.key which doesn't cause Apache to prompt for a password.

Here we create an insecure version of the server.key. The insecure one will be used for when Apache starts, and will not require a password with every restart of the web server. But keep in mind that while this means you don't have to type in a password when restarting Apache (or worse -- coding it somewhere in plaintext), it does mean that anyone obtaining this insecure key will be able to decrypt your transmissions. Guard it for permissions VERY carefully.

openssl rsa -in server.key -out server.key.insecure
mv server.key server.key.secure
mv server.key.insecure server.key

These files are quite sensitive and should be guarded for permissions very carefully. Chown them to root, if you're not already sudo'd to root. I've found that you can chmod 000 them. That is, root will always retain effective 600 (read) rights on everything.

(2) Copy files into position and tweak Apache.

Some professors like to pause for a moment after a long lecture, and do a little recap. It's a good pedagogical tool, so let's do so here. If you took route 1A above, you should have four files in a working directory:

server.crt: The self-signed server certificate.
server.csr: Server certificate signing request.
server.key: The private server key, does not require a password when starting Apache.
server.key.secure: The private server key, it does require a password when starting Apache.

If you took route 1B and created a CA, you'll have two additional files:

ca.crt: The Certificate Authority's own certificate.
ca.key: The key which the CA uses to sign server signing requests.

The CA files are important to keep if you want to sign additional server certificates and preserve the same CA. You can reuse these so long as they remain secure, and haven't expired.

At a bare minimum, the following considerations must now be addressed:

* You'll need a virtual host and document root set up for the SSL instance.
* You'll need to turn on the SSL engine and enable/load the SSL module.
* Apache must reference server.crt and server.key somewhere in its configuration.
* Apache must be listening to a port for which SSL is enabled (443 is default).

The particulars differ between Linux distros and versions of Apache. I'm only able to keep the Setting up SSL: Ubuntu and Apache 2 documentation current due to time constraints. Those steps should apply broadly to Debian-based distros with little or no modification. Red Hat and openSUSE commentary is kept online here for historical purposes.

Setting up SSL: Ubuntu and Apache 2
Setting up SSL: Red Hat and Apache 1.3.x
Setting up SSL: openSUSE

Credit : http://www.tc.umn.edu/~brams006/selfsign.html

HowTo make two instance of postfix running on same machine

HowTo make two instance of postfix running on same machine
Posted by Nikesh Jauhari

http://linuxpoison.blogspot.com/2008/02/howto-make-two-instance-of-postfix.html


What's involved?

Creating a second instance of Postfix from an existing one involves the following steps:

1. Add an IP address to the server
2. Copy the /etc/postfix directory and all files
3. Create an additional spool directory
4. Edit the config files
5. Create startup and administration scripts

Step one: Add an IP address

The second instance of Postfix will be used for all outbound e-mail. Users will configure their e-mail clients to connect to that IP as their "SMTP server".

Follow the procedure appropriate to your server's version of Linux to add a second IP. The new IP can exist on the same network card as the first (eg. as device eth0:1 on Linux) or can be tied to a second NIC, whichever best suits your requirements.

The new IP address must resolve to a name. Either add a name for it in your DNS, or add an entry in the server's /etc/hosts file. Postfix will not work unless the IP address resolves to a name on the server Postfix is installed on.

As an alternative, the new instance can share the same IP but receive mail on a port other than port 25. We won't show that here, but it's an alternative to be aware of.

Step two: copy /etc/postfix

Copy your existing /etc/postfix directory to /etc/postfix-out:

cp -rp /etc/postfix /etc/postfix-out

The new directory should have all the files with the same ownership and permissions as the original.

To make the next step easier, edit file /etc/postfix-out/main.cf. Change the following setting or add it if it does not exist:

queue_directory = /var/spool/postfix-out

Save the changes to the file before proceeding to the next step.

Step three: create an additional spool directory

Each instance of Postfix must have it's own mail spool directory. To avoid file conflicts, the default directory /var/spool/postfix must not be shared among instances.

Create a directory named /var/spool/postfix-out and let Postfix create the appropriate subdirectories and permissions:

mkdir /var/spool/postfix-out
postfix -c /etc/postfix-out check

The result should be directory /var/spool/postfix-out containing something similar to the following:

drwxr-xr-x 14 root root 336 Jan 30 10:20 .
drwxr-xr-x 15 root root 384 Jan 30 10:20 ..
drwx------ 2 postfix root 48 Jan 30 10:20 active
drwx------ 2 postfix root 48 Jan 30 10:20 bounce
drwx------ 2 postfix root 48 Jan 30 10:20 corrupt
drwx------ 2 postfix root 48 Jan 30 10:20 defer
drwx------ 2 postfix root 48 Jan 30 10:20 deferred
drwx------ 2 postfix root 48 Jan 30 10:20 flush
drwx------ 2 postfix root 48 Jan 30 10:20 incoming
drwx-wx--- 2 postfix postdrop 48 Jan 30 10:20 maildrop
drwxr-xr-x 2 root root 48 Jan 30 10:20 pid
drwx------ 2 postfix root 48 Jan 30 10:20 private
drwx--x--- 2 postfix postdrop 48 Jan 30 10:20 public
drwx------ 2 postfix root 48 Jan 30 10:20 saved

If directory /var/spool/postfix contains directories named etc, usr and lib, your first Postfix instance was probably installed chrooted: if those directories exist, manually copy them to /var/spool/postfix-out:

cp -rp /var/spool/postfix/etc /var/spool/postfix-out
cp -rp /var/spool/postfix/usr /var/spool/postfix-out
cp -rp /var/spool/postfix/lib /var/spool/postfix-out

Step four: edit the config files

Edit the file /etc/postfix/main.cf and add the following near the bottom of the file:

alternate_config_directories = /etc/postfix-out

The above setting is required to inform the Postfix daemons about the second instance.

Next, edit the file /etc/postfix-out/main.cf and change the following setting:

inet_interfaces = second-IP-address-NAME

Note: in the above you must specify the DNS name of the second IP address, not the IP address. If the IP address does not have a DNS name, add an entry for it to /etc/hosts so it can be resolved locally on the server.

You should also remove settings such as reject_maps_rbl and content filtering that only need to be applied to inbound e-mail, and change syslog_facility so logging of outbound mail sent to a different file than inbound.

You might also want to change the setting myhostname so the second instance uses a name difference than the first (eg. "mx1-out"). This is required if the two instances will exchange mail with each other, otherwise Postfix will complain mail "loops back to myself".

Lastly, you can force mail being sent from the outbound instance to send using the same IP address as the inbound instance. This is useful when the mail server is behind a firewall and you want only one IP address to communicate with the Internet. To send mail on a different IP, add the setting smtp_bind_address to main.cf similar to the following:

smtp_bind_address = 192.168.1.1

(Of course, replace the IP address above with your own server's inbound SMTP IP address)

Step five: Create startup and administration scripts
Startup script
The second instance can be started using the normal postfix start command, except you must point to the other configuration directory. For example:

postfix -c /etc/postfix-out start

To create a startup script for the second instance, either edit your existing Postfix startup script and add the above command after the existing postfix start command, or copy the existing startup script to a new name and change the copy. If you copy the start script, be sure to also follow your operating system's instructions for installing a new init script (for example, chkconfig on Redhat Linux, update-rc.d on Debian Linux).

Automatic Linux Server Backup using SSH

Example is given to backup files from hostserver to remoteserver.


---------Logging from hostserver to remoteserver without giving passwords--------

First you should create a user in both servers, in my case the username is backup_user.
I created them in both machine.

Then in hostserver, I created SSH private and Public key pairs using ssh-keygen (as given below) so that backup can be automated without inputing passwords. I did this as backup_user

#ssh-keygen -t rsa -b 1024
When you execute above command it will ask for several things, leave all them as default.
Then at one place it will ask for passphrase. At that point, without enter any password press enter key. (In other words, leave them blank)

Then you may see two files, id_rsa and id_rsa.pub in /home/backup_user/.ssh/

Now you should copy the pub key to the remote server. To do this,
execute following command :

ssh-copy-id -i /home/backup_user/id_rsa.pub backup_user@remoteserver

Now you should be able to login from hostserver to remoteserver without giving any password.



--------Making backups from hostserver to remoteserver------------------------------


**We need to create a script to make the nessary backups to backup_user's home directory with the date label.
eg: Following script will create a folder with date label and server name (eg. 20101223-hostserver).
Then it makes an archive of required folder in the newly created folder. (eg. in our case we get backup of mysql dir)

#backup script .This is saved in /home/backup_user/bak_script
mkdir /home/backup_user/`date +%Y%m%d`-hostserver
tar cfz /home/backup_user/`date +%Y%m%d`-hostserver/something.tar.gz /var/lib/mysql/xxxxx
chown backup_user:backup_user /home/backup_user/ * -R

****Then we should run this script as a ROOT level cronjob
Therefore first become as super user and execute following commands
crontab -e
and then add following

30 18 * * * /home/backup_user/bak_script
Above command says that bak_scipt has to be executed at 6.30 pm everyday.



****Following script is to copy the files to remoteserver

#script to archieve and then copy that to remoteserver. This is saved in /home/backup_user/copy_script

tar cfz /home/backup_user/`date +%Y%m%d`-hostserver.tar.gz /home/backup_user/`date +%Y%m%d`-hostserver
scp `date +%Y%m%d`-hostserver.tar.gz backup_user@192.248.8.17:/home/backup_user/backups

Then we should add a backup_user level cron to the above scipt and run that with some time after the above script
(USER level cron job)
crontab -e

and add folling things

30 19 * * * /home/backup_user/copy_script

According to this, all the files that we specified first backedup to hostserver it self at 18.30.
Then it will be transfered to remoteserver at 19.30. It is recommended to give sufficient time between copying files to server it self and copying to remoteserver.

Good luck

bdb_db_open: Warning - No DB_CONFIG file found in directory /var/lib/openldap-data: (2) Expect poor performance

"bdb_db_open: Warning - No DB_CONFIG file found in directory /var/lib/openldap-data: (2) Expect poor performance for suffix XXXXXXXX"


When I work on openLDAP on Fedora 10 platform I got above error.

Solution :

cp /usr/share/doc/openldap-servers-2.4.XX/DB_CONFIG.example /var/lib/ldap/DB_CONFIG
chown ldap:ldap /var/lib/ldap/DB_CONFIG
service ldap restart

This was working for me. Hope it will for you too. Gd lk.

To view the solutions for other platforms visit : http://readthefuckingmanual.net/error/1256/

hal.dll Problem - ' Windows root\system32\hal.dll '

Sometime after installing GRUB if you start Windows, it may give following error :
"
Windows could not start because the following file is missing or corrupt:
\system32\hal.dll.
Please re-install a copy of the above file.
"

Most of the time I found that, though this error asks us to reinstall hal.dll actually that is not the issue.

What you should try first is :
1. Boot from XP CD ROM
2. Enter to the Recovery Mode. You will be end up with C:\Windows\
3. now go upwards to c:\
4. Rename your Boot.ini. To do this you should type "rename boot.ini boot.ini.bak"
5. type : "bootcfg /rebuild" - This will analyze and rebuild your boot.ini. It may ask for identifier (Give "Windows OS") and the order (give "1")
6. Thats all, recovery is done. Now type exit and reboot your system. Now your Windows should work properly



If above solution doesnt help, you may try this :
1. Boot from XP CD ROM
2. Enter to the Recovery Mode. You will be end up with C:\Windows\
3. Now type : expand d:\i386\hal.dl_ c:\windows\system32\hal.dll (Here D: - CD ROM Drive and C: is the windows installation directory)
Try this. This didnt work me much. But may help to you guys.

Recover Linux GRUB - In Dual boot (Windows and Linux)

When we have both Windows and Linux in one computer (in dual OS mode)... If you install XP again, the Linux's boot loader will be overwrittn. In those cases you may need to recover the GRUB again.
To recover the GRUB follow these steps (These were helped me, hopefully to you too :) )

1. Put your RedHat CD 1
2. In the linux prompt type "linux rescue"
3. Follow the instructions (You may need to select language and various other things) - It also search for the existing Linux installation and let you know
4. You will end up with ‘sh#’ prompt. There type "chroot /mnt/sysimage/" and enter
5. Then type "grub-install /dev/hda"
6. Type "reboot"

These should work with RedHat family distribution. But it may also work with other distributions too.

Thats all. Now your Linux boot loader should work and you should be able to go to Linux and Windows.