SeyedMostafaAhmadi

# Create Group and User
groupadd your-groupname
adduser your-username --shell /sbin/nologin

# add your-username to your-groupname
usermod -aG your-groupname your-username

# Modify SSH Configuration File in /etc/ssh/sshd_config
Subsystem sftp internal-sftp
 

SeyedMostafaAhmadi

virt-install --name=test\
--ram=2048 --os-type=linux\
--cdrom=/var/lib/libvirt/images/debian-9.4.0-amd64-xfce-CD-1.iso\
--disk path=/dev/mapper/vg_kvm-db21_root\
--disk path=/dev/mapper/vg_kvm-db21_tmp\
--disk path=/dev/mapper/vg_kvm-db21_swap\
--network bridge=br0\
--vnc --noautoconsole

SeyedMostafaAhmadi

### create user name with specific password
CREATE USER 'newuser'@'localhost' IDENTIFIED BY 'password';

### create database
CREATE DADTABASE database-namee;

### grant all privileges to user for all databases
GRANT ALL PRIVILEGES ON * . * TO 'username'@'localhost';

### grant all privileges to user for specific database

SeyedMostafaAhmadi

# go to here path and add follow lines to this file /etc/tor/torrc
# previous install "obfs4proxy" package
####
UseBridges 1
ClientTransportPlugin obfs4 exec /usr/bin/obfs4proxy
Sandbox 0 # don't work with ClientTransportPlugin

Bridge obfs4 51.195.117.252:666 3275695F343201E2243B0E55E6C2F6476BDC91A7 cert=KybiRTmKQZiQmLk/Iuq9BHjWgIgHsbZ0pzrZCTZDeA6N7KWInqTxZc9TPpSfs88t25+MPA iat-mode=0
Bridge obfs4 87.106.157.198:55405 3C3893086B27E879778E4A6275E5230AA49132E9 cert=uZorJsxG11sfGmt2tsJRX6jCDQF043crM0vfsY+BJUdciPsszVN1eAem2zNteZ2WVjFqLg iat-mode=0
Bridge obfs4 51.79.51.112:51804 228199E09F51A406D0A3585463A47B82A9AF11AB cert=jgFDOR4fAkVvdCLHjCYv9+WKu4oilFhSWQGSlm8nlhfQ8gYLz24p5bTsF6jYL4ZxiYMlcw iat-mode=0

SeyedMostafaAhmadi

# for reduce lv in lvm on linux
# first enter follow command 
umount /dev/mapper/vg_name/lv_name
#
e2fsck -f /dev/mapper/vg_name/lv_name
#
resize2fs /dev/mapper/vg_name/lv_name   [fav_space]G
#
lvreduce -L [fav_space]G /dev/mapper/vg_name/lv_name
#

SeyedMostafaAhmadi

SELECT PARTITION_NAME, TABLE_ROWS FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_NAME = 'history';

SeyedMostafaAhmadi

# We can stop outputting the version of nginx and os by adding below command in nginx config in /etc/ngingx/nginx.conf to a http, server, or location context.
server_tokens off;
# Or if we want to remove the Server header completely, We need to compile Nginx with the Headers More module in, as the header is hard coded in the Nginx source, and this module allows changing any http headers.
more_clear_headers Server;
# for use top module we should install "apt install nginx-extras"

SeyedMostafaAhmadi

SELECT host, user, password, plugin FROM mysql.user;
which should return something like this (with unix_socket enabled):

+-----------+------+--------------------------+-------------+
| host      | user | password                 | plugin      |
+-----------+------+--------------------------+-------------+
| localhost | root | <redacted_password_hash> | unix_socket |
+-----------+------+--------------------------+-------------+

SeyedMostafaAhmadi

# When i was faced with this warning in lvm when i run lvm command it works but it took
# WARNING: Device /dev/dm-20 not initialized in udev database even after waiting 10000000 microseconds.
# It look my problem is solved by reloading udev rules without reboot with this command:
udevadm control --reload-rules && udevadm trigger

SeyedMostafaAhmadi

swapoff -a   #### Turn off the existing swap space
             #### create partition with enter n character, after enter this character enter partition number and start sector and space - write changes with enter w
partprobe    #### reread partition table
             #### add this line `/dev/specific-device   none            swap    sw              0       0` ### modify /etc/fstab file for mount startup 
mkswap /dev/specific-partition 
swapon -a    #### activate created swap particion