Tag Archives: Linux

Encrypt/Decrypt File with Vim Editor

In this howto we will see how to encrypt and decrypt a file with Vim editor.

Lets Encrypt a file:

linux-06ac:/opt # vim -x encryptedfile.txt
Warning: Using a weak encryption method; see :help 'cm'
Press ENTER or type command to continue

Now Press enter and it will ask you to set a password.

Enter encryption key: **********
Enter same key again: **********

Once you setup the password, you will be presented with the blank page where  you can start writing to the file as you do with Vim.

I am writing ” Helo Linux World” as an example to my encryptedfile.txt , save and quit with :wq

Not cat the file

linux-06ac:/opt # cat encryptedfile.txt 
VimCrypt~01!q"[�HY�&!���+B]3linux-06ac:/opt #

We can see that the file is Encrypted.

 

Decrypt the File:

To Decrypt permanently, open the file as following:

linux-06ac:/opt # vim encryptedfile.txt

Give the password to the file , you set while encrypting it.

Then type :X and press enter twice (without typing anything) when asked for “Enter encryption key:”

Now save and exit with :wq and viola the file is decrypted.

linux-06ac:/opt # cat encryptedfile.txt 
Helo Linux World

Thanks & Regards,

Salman A. Francis

YouTube: YouTube.com/Linuxking
Twitter: linuxking77
Facebook: https://www.facebook.com/groups/LZHProject/

HowTo Mount 8TB USB in CentoS 7 Server.

This howto is about “How To mount 8TB External USB” in CentOs 7 server.

# yum – y install epel-release

# yum -y install ntfs-3g

# lsblk

sdc 8:32 0 7.3T 0 disk
└─sdc1 8:33 0 7.3T

# mount -t ntfs /dev/sdc1 /mnt/

# ls -ltr /mnt

You will see it’s mounted.

Thanks,

Salman A. Francis

YouTube: LinuxKing

Facebook: Linuxking77 – LZHProject

How to Install PhPMyAdmin on Centos 7 from source

Dear Friends,

First of all we will install required repositories.

[root@itpings opt]# rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm
[root@itpings opt]# yum -y install epel-release

Now we will install apache, mariadb, mariadb-server and php56

[root@itpings opt]# yum -y install httpd mariadb mariadb-server php56w php-mbstring php-mysql php-soap

Once installed we will download phpmyadmin from phpmyadmin.net

[root@itpings opt]# wget https://files.phpmyadmin.net/phpMyAdmin/4.7.2/phpMyAdmin-4.7.2-all-languages.zip

unzip the content and move it to /var/www/html and rename the unzipped content to phpmyadmin

[root@itpings html]# unzip phpMyAdmin-4.7.2-all-languages.zip
[root@itpings html]# mv phpMyAdmin-4.7.2-all-languages.zip phpmyadmin

Now Change the ownership of the folder

[root@red html]# chown -R apache.apache phpMyAdmin
[root@red html]# chmod -R 755 phpMyAdmin

Now we will copy config.sample file to config.ini.php

[root@itpings html]# cp config.sample.inc.php config.inc.php

Now we will edit config.inc.php and only add root user and password of mysql ( Make sure you have root user and password of mysql)

/* User used to manipulate with storage */
 $cfg['Servers'][$i]['controlhost'] = '';
// $cfg['Servers'][$i]['controlport'] = '';
 $cfg['Servers'][$i]['controluser'] = 'root';
 $cfg['Servers'][$i]['controlpass'] = 'itpings123';

Now to visit phpmyadmin visit http://<your-ip-address>/phpmyadmin and provide the above user and password.

Done

Thanks,

Salman A. Francis
YouTube: Linuxking
Facebook: LZHProject, Linuxking77

How to Add Physical Disk to Increase Size of /dev/mapper/centos-root

Dear Friends,

I ran into a problem where my openstack machine ran out of space. My Logical FS /dev/mapper/centos-root was only 50GB and most of the space was lost.

Solution:
LVM

I Added a new 500GB HDD (sdb), created partition with parted (sdb1) and gave the below commands:

[root@stack opt]# pvcreate /dev/sdb1
Physical volume "/dev/sdb1" successfully created

Next Check your Volumes with “vgdisplay” command

[root@stack opt]# vgdisplay 
 --- Volume group ---
 VG Name centos
 System ID 
 Format lvm2
 Metadata Areas 1
 Metadata Sequence No 4
 VG Access read/write
 VG Status resizable
 MAX LV 0
 Cur LV 3
 Open LV 3
 Max PV 0
 Cur PV 1
 Act PV 1
 VG Size 465.27 GiB
 PE Size 4.00 MiB
 Total PE 119109
 Alloc PE / Size 119109 / 465.27 GiB
 Free PE / Size 0 / 0 
 VG UUID TrvUI3-Xt7U-6vzF-5RtW-OfK0-OCOy-Tejrb6
 
 --- Volume group ---
 VG Name cinder-volumes
 System ID 
 Format lvm2
 Metadata Areas 1
 Metadata Sequence No 5
 VG Access read/write
 VG Status resizable
 MAX LV 0
 Cur LV 0
 Open LV 0
 Max PV 0
 Cur PV 1
 Act PV 1
 VG Size 20.60 GiB
 PE Size 4.00 MiB
 Total PE 5273
 Alloc PE / Size 0 / 0 
 Free PE / Size 5273 / 20.60 GiB
 VG UUID 9LDtLm-52Un-1QJA-yc3q-13vE-LqEc-hX0kiU

Continue reading

Linux Tips ( grep the text without hashes and blank lines )

In our second post of linux tips i would like to share a very simple example in which i will use grep tool to remove all the hashes and blank lines from a file.

In our example we will use file1.txt with the following content

linux-11oz:/test # cat file.txt 
#The file with hashes
###
####
##

This is a test file

With lots of spaces


and few lines with


####hashes
###

So lets remove the hashes and blank lines with single grep command

We can use the following trick

linux-11oz:/test # grep . file.txt | grep -v "#"
This is a test file
With lots of spaces
and few lines with

The “.” will remove the blank lines and  “-v” will invert the match of #

Thats how simple it is. If you know a better way of doing it , Please send me an email or comment.

Email: learning@itpings.com

Thanks

Salman A. Francis

 

Linux Tips ( chmod tip )

Hey Guys this is going to be a new series of posts in which i will be sharing some cool linux tips.  You can watch the video of this post on http://www.youtube.com/linuxking

So here is the first tip Chmod:

I hope you guys are already familiar with chmod command if not checkout my Youtube “Linuxking” channel for theses commands.

With Chmod you can change the mode of the files and directories.
e.g
chmod 775 dir  command will change the permission on directory with rwxrwxrw-

Also using -R option with chmod will change the permission on the directory as well the content within the directory with same permissions.

However lets say you want to change the permissions of a directories to executable within a directory without changing permissions of file use the below tip.

Lets say you have a directory “test1” & “test2” inside “test” directory

test directory has also a  file inside it called file1.txt

file1.txt has permission rw——-

directory test1 has permission rwx——

directory test2 has permission rw——-

linux-11oz:/test # ls -ltr
total 0
-rw------- 1 root root 0 Mar 22 17:06 file.txt
drwx------ 1 root root 0 Mar 22 17:07 test2
drwx------ 1 root root 0 Mar 22 17:07 test1

Now if you try to change the permission with a simple ” chmod -R command ” of all the directories to “executable” inside test directory you could also change permission of the file inside test diretory.

Example:

linux-11oz:/ # chmod -R ug+x test/
linux-11oz:/ # cd test/
linux-11oz:/test # ls -ltr
total 0
-rwx--x--- 1 root root 0 Mar 22 17:06 file.txt  (You can see that the file also became executable)
drwx--x--- 1 root root 0 Mar 22 17:07 test2
drwx--x--- 1 root root 0 Mar 22 17:07 test1

Now to avoid such situation we will use X instead of x, lets see the impact of X with chmod command

linux-11oz:/ # chmod -R ug+X test/
linux-11oz:/ # cd test/
linux-11oz:/test # ls -ltr
total 0
-rw------- 1 root root 0 Mar 22 17:06 file.txt (You can see the file's permission has not changed to executable)
drwx--x--- 1 root root 0 Mar 22 17:07 test2
drwx--x--- 1 root root 0 Mar 22 17:07 test1
linux-11oz:/test #

I hope you have Enjoyed this tip, keep visiting our site for more information.

Recovery of the File System from Disaster

Hey Guys, long time no see…Well i am back and this time the issue is File System.

What Happened ?

Well My Backup Server’s root partition ran out of space due to some issue, and since it was on LVM (Logical Volume Manager) i took some space from my /home partition (it was 400 GB ) and added to my root partition. Following commands were used to resize the partition.

umount /dev/mapper/centos-home

lvreduce -L 200G /dev/mapper/centos-home

Note first i unmounted the partition and then reduced the space from my /home partition which was mounted as /centos-home
I took 200 GB out of it and added to my root partition.

The Mistake: I forgot to remount /home to /dev/mapper/centos-home

But i extended the partition with the following command:

lvextend -r -l+100%FREE /dev/mapper/centos-root

As per above command the partition will be re-sized to the 100% free space available from the reduced volume. Of course it was 200 GB. All was good when i saw the partition sized changed from no space to +200 GB. But then i realized that i was not able to mount /home to /centos-home and that was the time when all problem started. I “Rebooted The Machine” and when it came back it refused to enter the normal boot prompt but went into “Emergency mode”

Things i Tried:

I tried to fix the partition with xfs_repair tool , but in vain , and i received the error that “Cannot Find Super Block “

I tried to run the fixes couple of time but failed every time.

The Fix:

I fixed the issue by the following commands:

lvremove /dev/mapper/centos-home
lvcreate -L 200GB -n home centos

mkfs.xfs /dev/centos/home

mount /dev/mapper/centos-home

Luckily there was no important data on my /home partition and i was able to save my server.

Good Practice:

If you every fall prey to such situation, remember to “Backup” to an external drive and then proceed with the above mentioned technique to rescue yourself from such difficult situation.

I hope it will help some one some where, Let me know with your feedback.

Thanks & Best Regards,

Salman A. Francis

Linux Practical Security Course

Dear Members ,
I am happy to announce that Linux Practical Security by LZH Project is complete. We will launch it shortly. Please support us by buying and rating this course. For first 20 buyers there will be a discount of $5. Total cost is $25. You can also book your copy by sending me email to learning@itpings.com Please take a look at the introductory video here:

Openstack dashboard gives error “Error: Unable to retrieve information”

So today i ran into one more issue with Openstack , the error showed up  when i logged in to the dashboard and clicked on Project–>Instances.

What i saw terrified me because is saw “NOTHING” !

A day before i had the same issue and i thought it’s related to RAM so i restarted and everything started and operated normally, but this time the reboot didn’t help.

So i started scratching my head and started wondering what might be the reason. I searched internet but no success. I searched log files but nothing made sense at that time, so i rebooted one more time and an Error appeared saying something like “Openstack glance-registry api error limit reached ” So that gave me a head start that it has something to do with system being low in space.

A df -h showed that / is 100% full. I removed some unnecessary files , rebooted the system and Viola !

All started to work Normally.

Conclusion:

Make Sure you have enough space with OpenStack