3 ways to reset root password in linux

today I'm gonna to explain how to reset root password in linux. 2 of this ways can be applied only if you have access to PC physically. 3rd way can be applied if your service provider have recovery console or something like that:)

so lets start:

1 EDITING LOADER (in my case it will be GRUB)

boot machine
when the GRUB menu appears, use arrow keys to choose OS to be booted
press letter "e'' on the keyboard to enter edit mode
use arrow keys to select the kernel line for kernel to be booted
press "e" to edit line
go to end of line and type "single" (without quotes) as a separate word
press ESC key to exit the edit mode
press "b" to boot into single user mode
after booting you can set password for root by running passwd  commnad
reboot and login with new pw


If the easy method doesn't work on your machine, another way to solve the "lost root password" problem is to boot your computer from your Linux Installation CD/DVD, or from a live-CD/DVD such as Knoppix.

Boot with the live-disk then go to a terminal and su to root (no password is required) then issue the following commands (be sure to replace each /sda1 with your own root partition device):

mount -o dev,rw /mnt/sda1
cd /mnt/sda1/etc
Once you are into your system /etc directory, you can use a text editor (vim, nano, pico, etc.) to edit the /etc/shadow file where the password is stored. Various information about root and user accounts is kept in this plain-text file but we are only concerned with the password portion.

For example, the /etc/shadow entry for the "root" account may look something like this:

Now, using your favorite editor (I'll use vim) delete the password hash. For this example, the password is in green text and is all those characters between the 1st and 2nd colons.

vim shadow
After you've edited this field, it should look like this:

Now save the file and change back to the root directory and unmount the system root partition (don't forget to change the /sda1) as follows:

cd /
umount /mnt/sda1
Now reboot the computer.

Once the computer has booted and you're at the login prompt, type "root" and when asked for the password just press ENTER (entering no password). After a successful login, you need to set the new password for root using the following command:

this way was not tested by me and I found it in google :)

1.Boot from LIVECD or in RC
2. mount root partition
- if no raid on server than
mount /dev/hda2 /mnt/newroot
- if you have raid
mount /dev/md1 /mnt/newroot
NOTE make sure that you replace hhd name with your own

3. Bind /dev/random from your server
mount –bind /dev /mnt/newroot/dev
4. changing the root file system. (e.g.):  
# chroot /mnt/newroot /bin/bash
5.change root password
6. reboot in normal mode


installin JDK and JRE gentoo way

had a task to install JDK and JRE on customer server. And when I found that on server Gentoo has been installed it was too late for me :) ( it is my first experience with Gentoo)

so there are the steps

1. update portage

#emerge --sync

2. install JDK/JRE

# emerge virtual/jdk
# emerge virtual/jre

3. Configuring JVM

list of java virtual machines
# java-config --list-available-vms
out put should be like:
# java-config --list-available-vms
The following VMs are available for generation-2:
1)      IcedTea6-bin 1.4.1 [icedtea6-bin]
2)      Sun JDK [sun-jdk-1.5] (Build Only)
3)      Sun JDK [sun-jdk-1.6]
set VM

(By handle (preferred))
# java-config --set-system-vm sun-jdk-1.6
Now using sun-jdk-1.6 as your generation-2 system JVM
(By number)
# java-config --set-system-vm 3
Now using sun-jdk-1.6 as your generation-2 system JVM

ref http://www.gentoo.org/doc/en/java.xml


Mysql master-master replication

Today I’m going to write a short manual how to create failover mysql cluster.
What we need:

Server1 = master 1/slave2
Server2 = master2/slave2
Internal or external IPs (in this example I will use server1 _ip and server2_ip)
Replication user = replicau

Step-by-step how to:
Step 1.
On server 1 in my.cnf we need to add following lines

#master config
Server-id =1
Log-bin = mysql-bin
binlog-do-db = test_db
… #we can add as many DB as we need to replicate
#slave config
replicate-do-db = test_db
… #we can add as many DB as we need to replicate
master-host = server2_ip
master-user= replicau
master-password =password_of_user_replicau
master-port = 3306

same lines we should add in my.cnf on server2, the only thing we should change is master-host parameter to use server1_ip instead of server2_ip and change server-id parameter
Step 2
Restart mysql servers
Step 3
On each server we need to create replication user:

mysql>GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'replicau'@'server2_ip' IDENTIFIED BY 'password';

mysql> GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'replicau'@'server1_ip' IDENTIFIED BY 'password';

Step 4
Add server2 as slave to server1
- we need to set read_only parameter as ON on server1 (master 1)

mysql> SET GLOBAL read_only = ON;
mysql> show master status;
mysql> show master status;
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
| mysql-bin.000006 | 7984 | | |
1 row in set (0,00 sec)
on server2

mysql>slave stop;
mysql> CHANGE MASTER TO MASTER_HOST = "server2_ip", MASTER_USER = "replicau", MASTER_PASSWORD = "password_of_user_replication", MASTER_LOG_FILE = "mysql-bin.000006", MASTER_LOG_POS = 7984;
mysql> slave start;

on server1

mysql> SET GLOBAL read_only = OFF;

on server2 check connection status

mysql> show slave status;

if we do not receive any errors, everything is perfect 

Step 5
Do Step 4 for connecting server 1 as slave to server2.

Step 6
Check if everything is fine, if no try from step 1 

Step 7
It’s time to have a cup of coffee/tea of a bottle of beer


enable snmp windows 7

To install SNMP on Windows 7, open Control Panel and then click on Programs and Features. Then, click on "Turn Windows features on or off" link in the left pane. If UAC prompted, then click on Yes. Then, in the Windows Features window, scroll down and select "Simple Network Management Protocol (SNMP)" check box and click on OK. Then, wait for some time to install SNMP.

After installing SNMP, click on Start Orb and then type Services.msc in the Search box and hit Enter. Then, scroll down in the right pane and right click on SNMP Services and select Properties. Then, click on Traps tab. Now, in the Community Name box, type the community name to which your computer will send trap messages and then click on "Add to list" button. Then, click on Apply and then OK.