Sciencefox Q&A - Where Science man fail - Recent questions and answers

Answered: How can I flush DNS on Windows 7?

Mon, 17 Oct 2011 20:00:02 +0000

C:\>ipconfig /flushdns

Windows IP Configuration

Successfully flushed the DNS Resolver Cache.

Answered: How can I see my disk space or drive information in Linux?

Sun, 16 Oct 2011 05:40:21 +0000

For more readability you can use:

df -h

Answered: How can I view the running processes on a Linux system?

Sat, 15 Oct 2011 17:30:04 +0000

Issue comand "ps aux".

Answered: How do I delete a large directory in Windows?

Sat, 15 Oct 2011 07:13:46 +0000

You can do it using the Command Prompt:

rd /s /q folder_name

Answered: How can i see running services and runlevels in Centos ?

Thu, 13 Oct 2011 14:14:18 +0000

The easiest way is by issuing the command chkconfig --list

Answered: How can i make a 301 redirect?

Tue, 11 Oct 2011 17:35:50 +0000

The most simple way is by adding the following line into the .htaccess file :

Redirect 301 / http://your-new-site.com/

Answered: How can i install OpenVPN on Linux

Tue, 11 Oct 2011 16:56:12 +0000

OpenVPN with TAP0 interface

SERVER CONFIG

1. First we install the package using : #yum install openvpn

2. Then we give : #cd /usr/share/openvpn/easy-rsa/2.0

In this directory we execute the commands :

#sh vars
#sh clean-all source vars
#sh build-ca - generates certificate authority
#sh build-key-server server -it generates the server key
#sh build-key client1 - generates the certificate and keys for one client, client1
#sh build-dh - generates Diffie Helman parameters

After those commands, in /usr/share/openvpn/easy-rsa/2.0/keys/ directory we will have the following files :

01,02.pem
ca.crt - Root CA certificate
ca.key - Root CA key
client1.crt - Client1 Certificate
client1.csr - Client1 Certificate Signing Request
client1.key- Client1 Key
dh1024.pem - Diffie Hellman parameters
server.crt - Server Certificate
server.csr - Server Certificate Signing Request
server.key - Server Key

From this files, on the client machine we must copy : ca.crt ; client1.crt ; client1.key

Let us consider that : a.b.c.0 = VPN private class (ex 172.16.0.0)
e.f.g.0 = company LAN private class (ex 192.168.0.0)

3. Now we must edit the configuration file - server.conf

If in /etc/openvpn we do not find server.conf, we will copy it from din usr/share/doc/openvpn-2.1.1/sample-config-files

Then in this file we must check the followings :

dev tap
server a.b.c.0 255.255.255.0 - VPN private class - MUST be different than LAN class
push "route e.f.g.0 255.255.255.0" - the server lan
client-to-client
;certificate paths
ca ca.crt
cert server.crt
key server.key
dh dh1024.pem

*the easiest way is to copy those files from /usr/share/openvpn/easy-rsa/2.0 to /etc/openvpn/

4. Then on the gateway machine we must add an route to route the VPN subnet (172.16.0.0) to the LAN ip of the OpenVPN server. This is necessary only if the VPN server and the gateway are on different machines.

For doing this we have two options:

a) on the gateway we add a route :#route add 172.16.0.0 mask 255.255.255.0 192.168.0.X - 192.168.0.X lan ip of the server ; or
b) on the OpenVPN server machine we issue #iptables -t nat -A POSTROUTING -s 172.16.0.0/24 -o eth0 -j MASQUERADE - with this one we will not have ping reply from vpn clients, so the first line must be added too :)

If we have a firewall in place we must give the following commands :

#iptables -A FORWARD -i tap0 -j ACCEPT
#iptables -A INPUT -i tap+ -j ACCEPT
#iptables -A FORWARD -i tap+ -j ACCEPT

If we want that VPN clients to access the internet through the VPN tunnel :

- in /etc/openvpn/server.conf we must uncheck : push "redirect-gateway def1 bypass-dhcp"
- issue the following:# iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to xx.xx.xx.xx - xx.xx.xx.xx =internal adress of gateway server (ex:19.168.0.1)
(if the VPN was on GW machine , xx.xx.xx.xx = server routable/external IP)

5. For OpenVPN to run at startup we issue : #chkconfig openvpn on

6. To start OpenVPN server : #service openvpn start

CLIENT CONFIG

(we suppose that we run the client on Windows)

In client.ovpn file we must have :

client
dev tap
proto tcp
remote ip_extern_server_vpn port
ca \path\to\ca.crt
ca \path\to\client1.crt
ca \path\to\client1.key

OpenVPN with TAP0 bridge

For install we follow same steps as above.For configuring, we edit server.conf file, and make sure that we have

dev tap0
;server 172.16.0.0 255.255.255.0 - this line must be commented
server-bridge 192.168.0.X 255 255 255 0 192.168.0.Y 192.168.0.Z ; where: x- vpn server lan ip ; y-z ip range for vpn clients
;push "route 192.168.0.0 255.255.255.0" - this line must be commented
client-to-client
;certificate path
ca ca.crt
cert server.crt
key server.key

Then we check if we have bridge-utils by # yum install bridge-utils

Then in /etc/openvpn we modify bridge-start file with the parameters of the server lan card, from "# ifconfig eth0"

eth="eth0"
eth_ip=""
eth_netmask=".."
eth_broadcast"..."

After that we must make sure that we have a default route on the new bridge br0. If not, there will be no response packets to the client connect request packets,so the client will not be able to connect.

route add default gw 192.168.0.1 br0

If we have a firewall in place we must issue :

#iptables -A INPUT -i tap0 -j ACCEPT
#iptables -A INPUT -i br0 -j ACCEPT
#iptables -A FORWARD -i br0 -j ACCEPT

The run/stop sequence :

- run bridge-start script
- run openvpn
- stop openvpn
- run bridge-stop script

Answered: How can i disable PIN code request on a modem ?

Tue, 11 Oct 2011 16:48:37 +0000

1. Connect your modem to PC and run HyperTerminal

2. Issue command : AT - response should be "OK"

3. Check if SIM card has pin with : AT+CPIN?

4. If the SIM has no pin, the reply should be : +CPIN: READY

5. If you have a PIN, you must enter : AT+CPIN="1111" , where 1111 is your current PIN

6. To disable the PIN use : AT+CLCK="SC",0,"1111" , where 1111 = your current PIN code

7. The SIM will now have the PIN code disabled.

Answered: How can i make Intel PRO 1000 work on Untangle?

Tue, 11 Oct 2011 16:47:32 +0000

If you use Untangle in your network, and you have issues with Intel PRO 1000 cards, here is how to solve it :

1. Login to your box as root

2. To check if the system has detected your card, run "lspci | grep Ethernet" and look for a line like this : Ethernet controller: Intel Corporation 82574L Gigabit Network Connection

3. Download latest drivers from Intel ,directly from here

4. Add "deb http://ftp.us.debian.org/debian lenny main contrib non-free" to your /etc/apt/sources.list.d file

5. Run "apt-get update"

6. Run "apt-get install untangle-development-build"

7. Run "apt-get install linux-headers-2.6.26-1-untangle-686"

8. "tar zxvf" the drivers from Intel into /usr/src/linux-headers-2.6.26-1-common-untangle/drivers/net/e1000e

9. From there run "make install" . It will start the install, and then suddenly stop complaining about some error. But, ignore it, because just a few lines ahead, it compiled the "e1000e.ko" file that you need.

10. Issue the following commands :
rmmod e1000e
depmod -a
insmod /usr/src/linux-headers-2.6.26-1-common-untangle/drivers/net/e1000e/e1000e.ko

11. Log into Untangle web interface, then Config/Networking, and you should see your the new card.

12. To maintain consistency after restart issue the following command :
mkinitramfs -o /boot/initrd.img-2.6.26-1-untangle-686

Answered: How can i change the root password in Debian Linux

Tue, 11 Oct 2011 16:44:30 +0000

how to change root password

In case that you forgot your root password, and you are using Debian Linux, here's what you can do (might work also on some other Linux flavors):

1. On the grub boot prompt, press “e” to enter edit mode

2. Then go to the line that starts with “kernel” and press “e” again

3. At the end of this line write “init=/bin/sh” or “/bin/bash”

4. After that press Enter to make that changes effective, and then and press “b” to boot

5. After the booting, at the # prompt issue the command : “mount -o remount rw /”

6. Finally type “passwd” and change the root password

7. To reboot, use “init 6” or “reboot”

Answered: How can i rename home button in Wordpress ?

Tue, 11 Oct 2011 16:41:43 +0000

If you want to change your WordPress blog "Home" button to a something more meaningful (for example, tutorials :) ) you can do it like this :

1. On your server, go to /location/of/your/wordpress/wp-content/themes/your-theme/header.php

2. Enter command : chmod 646 header.php

3. In WordPress Admin go to Appearance / Editor , from the left menu

4. At upper right corner, be sure to have your theme selected

5. Then, from categories on the right click on " Header (header.php) "

6. Search for the term "home" and you will find something like this :
<?php echo lw_homebtn(__('Home','lightword')); ?>

7. Replace Home with another term that you want , and click Update

8. Go to /location/of/your/wordpress/wp-content/themes/your-theme/header.php

9. Return to header.php defaults : chmod 644 header.php

Answered: How can i change page order in Wordpress?

Tue, 11 Oct 2011 16:40:29 +0000

1. Log into WordPress Admin

2. From the menu on the left go to Pages, put the mouse over a page name, then click Edit

3. On the right, on the Page attributes tab assign a number to the "Order" field.

4. Do the same for all pages.

5. Pages will be sorted by the order number.

Answered: PHP script for translation of multilingual website ?

Tue, 11 Oct 2011 16:39:45 +0000

Let's say you have a bilingual site, in my case English and Romanian language.

If your visitors want to jump to the translated version of the page that they are currently viewing, you can use a little php script that creates a link to a translated page.

In my case the website was built like this :

Romanian version page names : index.php, contact.php, services.php

English version page names : index-en.php, contact-en.php, services-en.php

So, all the script has to do, for changing the link from Romanian to English is to :

1. Get the name of the current page

2. Replace .php ending name of the page with -en.php

3. Display the href link.

The script – placed somewhere in the beginning of the page :

<?php
function curPageName() {
return substr($_SERVER["SCRIPT_NAME"],strrpos($_SERVER["SCRIPT_NAME"],"/")+1);
}
$string = curPageName();
$patterns = '/.php/';
$replacements = '-en.php';
$eng_text = preg_replace($patterns, $replacements, $string);
?>

And now to show the link to the translated version of the page :

<a href="<?php echo $eng_text; ?>" title="English language">English version</a>

Notice :

- both pieces of the code must be in the same page.
- the page is a php page

My website was buit like this for the Romanian part : index.php contains the following code :
<?php
include ("top.php");
include ("index_code.php");
include ("footer.php");
?>

In my case the php code is in the beginning of the index-code.php page, and the html code is near the end.

For the English part of the site I have the following setup : index-en.php contains :

<?php
include ("top-en.php");
include ("index_code-en.php");
include ("footer-en.php");
?>

To change the link from English pages to Romanian the code is like this :

<?php
function curPageName() {
return substr($_SERVER["SCRIPT_NAME"],strrpos($_SERVER["SCRIPT_NAME"],"/")+1);
}
$string = curPageName();
$patterns = '/-en.php/';
$replacements = '.php';
$ro_text = preg_replace($patterns, $replacements, $string);
?>

And the line to add the link :

<a href="<?php echo $ro_text; ?>" title="English language">English version</a>

Notice the name of the replaced string is changed : it's now called ro_text instead of eng_text.

Answered: Can somebody explain me how to use crontab in Linux

Tue, 11 Oct 2011 16:36:13 +0000

Of course. Here is some tutorial about it.

Each Linux user can have his own crontab, located in /var/spool/cron/crontabs. Those files must not be edited directly but through crontab -e command

A user cronjob looks like this

1 2 3 4 5 /path/to/command arg1 arg2

Where :

1 means minute (0-59)
2 means hours (0-23)
3 means day (0-31)
4 means month (0-12); 12=December
5 means Day of the week(0-7); 7 or 0=Sunday
/path/to/command means command to execute
arg1,arg2 = command arguments

Example

If you wish to run script.sh every day at 10:00 am, your crontab should look like this

0 10 * * * /location/of/script.sh

An operator allows you to specifying multiple values in a field. There are three operators:

- asterisk * : specifies all possible values for a field. As example, an asterisk in the hour field would mean "every hour"
- comma , : operator specifies a list of values, like 2,3,10,20,40
- dash - : specifies a range of values, for example: 6-9 days , which is equivalent to typing 6,7,8,9 using the comma operator.

Usually when a cronjob is executed a mail is send to the MAILTO variable in the crontab file.

If you want to disable mail sending you replace the default MAILTO=root with MAILTO=

If you want to disable mail sending for a particular job, you can add >/dev/null 2>&1 to the end of a job.

Instead of using the five parameters for minute,hour,day, etc you can use the special strings below

@reboot = Run once, at startup.
@yearly = Run once a year, “0 0 1 1 *”.
@annually = (same as @yearly)
@monthly = Run once a month, “0 0 1 * *”.
@weekly = Run once a week, “0 0 * * 0″.
@daily = Run once a day, “0 0 * * *”.
@midnight = (same as @daily)
@hourly = Run once an hour, “0 * * * *”.

To get crontab to run a task every 30 minutes you can type :
*/30 * * * * /path/to/command

Besides user crontab, edited with crontab -e you have also /etc/crontab/

/etc/crontab is system crontabs file. It is used by root or daemons to configure system wide jobs. All other users must use crontab -e command as described above.

Exemple /etc/crontab file :

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/

# run-parts
01 * * * * root run-parts /etc/cron.hourly
02 4 * * * root run-parts /etc/cron.daily
22 4 * * 0 root run-parts /etc/cron.weekly
42 4 1 * * root run-parts /etc/cron.monthly

If you want to add here a script to run as root every 45 minutes you can add :

*/30 * * * * root sh /path/to/script.sh

Remeber to press Enter after the last line, to put the cursor to a new line at the end of the file .Otherwise, the last cronjob will not run.

Answered: How to install GeoIP for AWStats?

Tue, 11 Oct 2011 16:34:08 +0000

1. Download GEOIP
#wget http://search.cpan.org/pub/CPAN/authors/id/B/BO/BORISZ/Geo-IP-PurePerl-1.25.tar.gz

2. Unzip it
#tar -zxvf Geo-IP-PurePerl-1.25

3. Install it
#cd Geo-IP-PurePerl-1.25
#perl Makefile.PL
#make
#make test

After make test command, it will complain about the lack of GeoIP databases. So, let us install those :

#mkdir /usr/local/share/GeoIP
#cd /usr/local/share/GeoIP
#wget http://geolite.maxmind.com/download/geoip/database/GeoLiteCountry/GeoIP.dat.gz
#wget http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz
#gunzip *

Then, we must continue the installation of GeoIP

#cd /to/the/directory/of/Geo-IP-PurePerl-1.25
#make install

4. Now we must tell AWStats about GeoIP databases location. Go to your awstats.example.com.conf and awstats.www.example.com.conf and modify/add :

#LoadPlugin="geoip GEOIP_STANDARD /usr/local/share/GeoIP/GeoIP.dat"
#LoadPlugin="geoip_city_maxmind GEOIP_STANDARD /usr/local/share/GeoIP/GeoLiteCity.dat"

Besides that you can also enable a nice built-in awstats plugin, to get more information about the ip's that visit you..

First you must issue the following commands:

#yum perl-Net-Whois-IP
#yum perl-Net-XWhois

Then, in awstats config files from above, you must uncomment the line
LoadPlugin="hostinfo"

Answered: Can somebody tell me how to install AWStats ?

Tue, 11 Oct 2011 16:32:25 +0000

Assuming that you have Centos 5.5, and Apache installed from source in /usr/local/apache you can install awstats like this

1. Add the RPM Forge repository with
rpm -Uhv http://apt.sw.be/redhat/el5/en/i386/rpmforge/RPMS/rpmforge-release-0.3.6-1.el5.rf.i386.rpm

2. Install AWStats
yum install awstats

3. Locate awstats.conf
updatedb
locate awstats.conf

It is possible for the yum installer to put the config in /etc/httpd/conf.d/awstats.conf

4. Move the config file into /usr/local/apache/conf/extra/awstats.conf

5. Be sure that all awstats file are into your Apache root directory - in our example : /usr/local/apache/htdocs

6. Edit the file awstats.conf according to your configuration

Alias /awstats/icon/ /usr/local/apache/htdocs/awstats/icon/

ScriptAlias /awstats/ /usr/local/apache/htdocs/awstats/
<Directory /usr/local/apache/htdocs/awstats/>
DirectoryIndex awstats.pl
Options ExecCGI
order deny,allow
allow from all
</Directory>

7. Go to /etc/awstats/awstats.localhost.localdomain.conf

Supposing your website is www.example.com, you must issue the following commands

cp awstats.localhost.localdomain.conf awstats.example.com.conf
cp awstats.localhost.localdomain.conf awstats.www.example.com.conf

In both those file modify like this :

SiteDomain="www.example.com
HostAliaseses="www.example.com localhost 127.0.01"
LogFile=/path/to/apache/access_log
LogType=W
LogFormat=4
LogSeparator=" "

8. Update the stats using this command
#/usr/bin/awstats_updateall.pl now -confdir="/etc" -awstatsprog="/usr/local/apache/htdocs/awstats/awstats.pl"

9. To check if it works, type in your browser :
http://www.example.com/awstats/awstats.pl or http://example.com/awstats/awstats.pl

10 To auto update the statistics every 30 mintues , add to /etc/crontab

*/30 * * * * user perl /usr/bin/awstats_updateall.pl now -confdir="/etc" -awstatsprog="/usr/local/apache/htdocs/awstats/awstats.pl"

where user is the user under which you want the awstats update to run

Remeber to press Enter after the last line, to put the cursor to a new line at the end of the file .Otherwise, the last cronjob will not run.

Answered: How can i migrate RAID in Ubuntu Linux?

Tue, 11 Oct 2011 16:25:57 +0000

This tutorial will explain how to go from 2x320 RAID1 HDD's to to 2x500 RAID1 HDD's

1. Make sure that your system can boot from either of 320 hdd’s.

2. Shutdown the system and replace one of the 320 hdd’s with one 500 hdd

3. Start the system, it should boot into degraded mode. If it doesn’t either check in bios to boot from the 320 hdd, or reattach old 320 hdd drive , swap it with the other 320 hdd.

In my case the 500 GB Hdd is now /dev/sda and the 320 gb hdd is /dev/sdb

4. Copy partition structure from sdb to sda

sfdisk -d /dev/sdb | sfdisk /dev/sda

In my case I had to add –force to the command because “partition 1 does not end at a cylinder boundary”.

5. Enter cfdisk /dev/sda. Delete /dev/sda3 , to add the free space to it. Recreate /dev/sda3 and set type to fd – linux raid. Make sure that /dev/sda1 is marked bootable

6. Add /dev/sda1 to md0, /dev/sda2 to md1, /dev/sda3 to md2

mdadm -–add /dev/md0 /dev/sda1
mdadm -–add /dev/md1 /dev/sda2
mdadm -–add /dev/md2 /dev/sda3

Linux will start syncing the partitions.

7. Next install grub on dev/sda

grub-install /dev/sda

8. Shutdown.Change the 320 hdd with the second 500 GB hdd. Restart.

9. Copy partition structure from sda to sdb (from 500gb hdd to 500gb hdd)

sfdisk -d /dev/sda | sfdisk /dev/sdb –force

10. Re-add sdb to md raid :

mdadm -–add /dev/md0 /dev/sdb1
mdadm -–add /dev/md1 /dev/sdb2
mdadm -–add /dev/md2 /dev/sdb3

11. Then we install grub on sdb too :

grub-install /dev/sdb

12. First we restart the system, and then we grow the partition :

mdadm --grow /dev/md2 --size=max

13. Unmount /dev/md2 : umount /dev/md2

If it’s not working on reboot then try to unmount it.

14. Run filesystem check :

e2fsck -f /dev/md2

15. Resize the filesystem

resize2fs /dev/md2

16. Run filesystem check again :

e2fsck -f /dev/md2

Answered: How can i limit SSH file transfer to a single directory ?

Tue, 11 Oct 2011 16:21:35 +0000

Let us suppose that you have a server, and you want to limit the access of an user only to a specific directory (for example home directory).

For that task you must have OpenSSH installed - a version greater than 4.8 , because lower versions will not recognize some commands (Match User directive). If you have a lower version please read the second part of this tutorial.

Assuming you have version greater then 4.8 here is what to do :

1. Add the user : #useradd -s /bin/false user1

2. In /etc/ssh/sshd_config we must : (supposing that the user's home dir is /home/user1)
- comment:
#Subsystem sftp /usr/libexec/openssh/sftp-server
- add:
Subsystem sftp internal-sftp
-after this, at the end of the file add those lines:

Match User user1
ChrootDirectory /home/user1
AllowTCPForwarding no
X11Forwarding no

3. Restart the SSH service : #/etc/init.d/sshd restart

4.Assign the necessary permissions

#chown root:root /home/user1
#chmod 0755/home/user1

Attention : Those are mandatory properties. Without those, the user can not login via sftp.

In this moment the user is only able to download the files already existing in that folder.
If we want to give him write access, we create a directory inside /home/user1 which user1 owns , an in which he can create files and directories.

--- Part Two ---

But what if you have OpenSSH version less than 4.8 (for example 4.3p2, which comes with CentOs 5.5) ? Here is what to do:

Basically, you create another ssh server, listening on another port, on which the user will make sftp chrooted.

1. Create another ssh init script, named let's say sftpinit and save it in /etc/init.d/sftpinit

#!/bin/bash
#
pidfile='/var/run/sftpinit.pid'
case "${1}" in
start ) exec -a /usr/sbin/sftpinit /usr/sbin/sshd -f /etc/ssh/sftpinit_config
;;
stop ) kill -9 $(cat ${pidfile})
;;
restart) stop
sleep 3
start
;;
* ) echo "Usage: ${0} (start|stop|restart)"
;;
esac
exit 0

2. #chmod 0755 /etc/init.d/sftpinit

3. If you want that server to run at startup : chkconfig --add sftpinit

4. Then, make a symbolic link : # ln -s /usr/sbin/sshd /usr/sbin/sftpinit

5. Create /etc/ssh/sftpinit_config with the following content :

Port 2000
Protocol 2
AddressFamily inet

SyslogFacility AUTHPRIV
LogLevel INFO

PermitRootLogin no

RSAAuthentication no
PubkeyAuthentication no
RhostsRSAAuthentication no
HostbasedAuthentication no
PasswordAuthentication yes
PermitEmptyPasswords no
ChallengeResponseAuthentication no
KerberosAuthentication no
GSSAPIAuthentication no

UsePAM no

PidFile /var/run/sftpinit.pid

ChrootDirectory /home/user1/
Subsystem sftp internal-sftp

6. Create the user user 1 (suppose it's home directory will be /home/user1) and assign a password:

# useradd -s /bin/false user1
# passwd user1 passworduser1

7. Assign proper rights:

#chown root:root /home/user1
#chmod 0755 /home/user1

8. Start the new ssh server with #service sftpinit start or #/etc/init.d/sftpinit start

Now on port 2000 you can make sftp with only user 1( because root login is disallowed). On your normal ssh port, you can not login with user1 (because his shell is /bin/false) and you can not make sftp.

In this moment the user is only able to download the files already existing in that folder

To give the user write access, we create a directory inside /home/user1 , (/home/user1/icanwritehere) which user1 owns , an in which he can create files and directories.

Answered: How can i make ip forwarding in Linux ?

Tue, 11 Oct 2011 16:18:01 +0000

Let us suppose that for your particular need (gateway, VPN, routing,etc...) you need to enable ip forwarding. This is a very easy task. Here is how to do it , assuming that your Linux distribution is Centos :

1) First you must check the status of ip forwarding and you can do this in two ways

#sysctl net.ipv4.ip_forward
or
#cat /proc/sys/net/ipv4/ip_forward

2) Now you can enable IP forwarding

a) with no persistence after reboot

#systcl -w net.ipv4.ip_forward=1
or
#echo 1 > /proc/sys/net/ipv4/ip_forward

b) permanent setting

edit /etc/sysctl.conf and add/modify a line like this :

net.ipv4.ip_forward=1

Also you can check /etc/sysconfig/network file to contain a line like this :

FORWARD_IPV4=true

3) If you choose to make it a permanent setting, you must now enable the changes from sysctl.conf

#sysctl -p /etc/sysctl.conf

4) Restart the network service

#service network restart

The ip forwarding is now enabled.

Answered: How to install a program in Safe Mode in Windows XP

Tue, 11 Oct 2011 16:15:46 +0000

By default, Windows Installer will not work in Safe Mode, so you can not install or uninstall programs in that mode.

To make it work, you need to create a registry entry for each mode of Safe Mode you log in with.

1. Safe Mode.

In a command prompt, give the command :

REG ADD “HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal\MSIServer” /VE /T REG_SZ /F /D “Service”

followed by :

net start msiserver

This will start Windows Installer Service.

2. Safe Mode with Network

In a command prompt, give the command :

REG ADD “HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Network\MSIServer” /VE /T REG_SZ /F /D “Service”

and then :

net start msiserver

This will start Windows Installer Service.

Answered: How to remember Linux path variables?

Tue, 11 Oct 2011 12:08:42 +0000

Edit your /home/user/.bash_profile and at the end of this file add:

PATH=$PATH:/your/new/path/dir
export PATH

Now, your path settings will be remembered.

Answered: Install MySQL from source anybody ?

Tue, 11 Oct 2011 12:06:36 +0000

1. First create a group named mysql :
#groupadd mysql

2. Then add user mysql that belongs to this group :
#useradd -g mysql mysql

3. Dowload it, with wget

4. Un-tar it and switch to MySQL directory :
#tar zxvf mysql-*
#cd mysql-*

5. Configure the install path to be : /usr/local/mysql
# ./configure --prefix=/usr/local/mysql

6. Compile and install :
#make
#make install

7. Copy the configuration file :
#cp support-files/my.medium.cnf /etc/my.cnf

8. Give proper rights
#cd /usr/local/mysql
#chown -R mysql .
#chgrp -R mysql .

9. Set up MySQL internal database :
#bin/mysql_install_db --user=mysql

10. Initialize/start MySQL. If it does not work from first attempt, reboot your server :
#/usr/local/mysql/bin/mysqld_safe --user=mysql &

11. Some more rights :
#chown -R root .
#chown -R mysql var

12. Install mysql using secure installation :

#cd /usr/local/mysql
#/usr/local/mysql/bin/mysql_secure_installation

13 To automatically start after reboot, from sources dir :

#cp support-files/mysql.server /etc/init.d/mysql
chmod 755 /etc/init.d/mysql
#chkconfig mysql on
#service mysql start

If you encounter some path errors , fix those with (paths are relative to this tutorial) :

#PATH=$PATH:/usr/local/mysql/bin
#export PATH
#PATH=$PATH:/usr/local/mysql
#export PATH

Security tip : if your database need to be accessed only by local applications, you can tell MySQL to listen only to local connections ( not even on port 3306), by editing /etc/my.cnf and adding :

Answered: How to install Apache from source on Linux

Tue, 11 Oct 2011 12:05:10 +0000

Get the latest Apache , then :

1. Un-tar it :
#tar zxvf httpd-*

2. Configure it, with install dir /usr/local/apache, enable-rewrite mod built in and with support for Apache modules ( enable-s0 command) :
#cd httpd-*
#./configure --prefix=/usr/local/apache --enable-rewrite --enable-so

3. Compile and install it :
#make
#make install

4. After this, apache can be started with :
#cd /usr/local/apache2/bin
#./apachectl start

5. Check if you have remnants of an older installation of Apache, for example another httpd.conf , and if in /etc/init.d there is an httpd file. If yes, rename or delete it.

6. If you want Apache to run an startup, download the following file , then :
#mv httpd.doc httpd
#chmod a+x httpd
#cp httpd /etc/init.d/httpd
# chkconfig httpd on

7. Another way to start Apache when installing from source is to set up a symbolic link for the apachectl utility (installed automatically as part of Apache):

#ln -s /usr/local/apache/bin/apachectl /etc/rc.d/init.d/apache

Then set up auto-start for runlevel 3 (where the server will go by default):

#ln -s /etc/rc.d/init.d/apache /etc/rc.d/rc3.d/S90apache

After that start the daemon:

#/etc/rc.d/init.d/apache start

---

Some notes about Apache installation:

1. There are two modes of compiling Apache modules :
a) built in , with --enable-modulename
b) shared , with --enable-modulename=shared . With this option, in /modules directory, modulename.so will be created, and we can load it in httpd .conf with a loadmodule directive.

Example : LoadModule rewrite_module /locatie/modul/mod_rewrite.so

2. If you want to include most of the modules in apache, configure it with --enable-modules=most or --enable-mods-shared=most

Answered: How can i install PHP from source on Linux?

Tue, 11 Oct 2011 12:02:08 +0000

1. Stop your webserver :
#/etc/init.d/httpd stop

2. Un-tar php :
#tar zxvf php-*

3. Configure it with the following options :
- install dir = /usr/local/apache/php
- apxs dir = /usr/local/apache/bin/apxs
- config file path = /usr/local/apache/php
- mysql directory = /usr/local/mysql
- cgi disabled
- zlib, mbstring, gd enabled
- with-imap, kerberos, imap-ssl, openssl, mcrypt are optional. For mcrypt you need : yum install libmcrypt libmcrypt-devel , for imap : yum install libc-client-devel

#cd php-*
#./configure --prefix=/usr/local/apache/php --with-apxs2=/usr/local/apache/bin/apxs --with-config-file-path=/usr/local/apache/php \
--with-mysql=/usr/local/mysql --disable-cgi --with-zlib --enable-mbstring --with-gd --with-png-dir=/usr/lib/
--with-imap --with-kerberos --with-imap-ssl --with-openssl --with-mcrypt

4. Compile and install it
#make
#make install

5. Copy config file to the directory defined when configuring:
#cp /alex/php-5.3.3/php.ini-production /usr/local/apache/php/php.ini

6. In /usr/local/apache/conf/httpd.conf we check/add the followings:

LoadModule php5_module modules/libphp5.so
DirectoryIndex index.html index.php

AddHandler php5-script .php
AddType text/html .php

AddType application/x-tar .tgz
AddType application/x-httpd-php .php
AddType image/x-icon .ico

7. Start your webserver
#/etc/init.d/httpd start

Answered: How can I backup a machine based on Linux?

Mon, 10 Oct 2011 05:47:02 +0000

Here is a quick backup idea for your Linux box.
Usually on your Linux system you have files (sites,documents..etc) and databases.

1) Backup all databases from MySQL :
#mysqldump -u root -p -A > all.sql

where:
-p = will prompt you for SQL root password
-A = all databases
-all.sql = the file where the databases will be backed to

2) Make an archive of all your files in the system
#tar -cvpzf backupfile.tar.gz --exclude=/backupfile.tar.gz --exclude=/proc --exclude=/lost+found --exclude=/sys --exclude=/mnt --exclude =/media --exclude=/dev/ /

where:
-c = new backup archive
-v = verbose mode
-p = keep file permissions
-z = compress backup with gzip
- exclude the backup file itself from the backup, and some system generated directories.
- / = at the end of the command, / is the directory that we want to backup. Because we want to backup all the filesystem we use the root directory, /

3) Restore the backup

Boot with a LiveCD and issue the following command (make sure the backup archive is not stored in the directories to be restored, or it will be overwritten) :

#tar -xvpzf /location/of/backup.tar.gz -C /

where :
-x = extract
-f = archive file
- C / = directory to extract, in our case, the root directory, /

4) Create the directories not included in backup
#mkdir /proc /lost+found /sys /mnt /media