March 2022 – Page 4

Flush Routing Table in Linux

March 4, 2022

Flush all routes

sudo ip route flush table main

ip route show

Empty a routing cache

sudo ip route flush cache

sudo ip route show cache

References
https://linoxide.com/how-to-flush-routing-table-from-cache/

Assign Output of Shell Command To Variable in Bash

March 3, 2022

var=$(command-name-here)
var=$(command-name-here arg1)
var=$(/path/to/command)
var=$(/path/to/command arg1 arg2)

OR use backticks based syntax as follows to assign output of a Linux command to a variable:

var=`command-name-here`
var=`command-name-here arg1`
var=`/path/to/command`
var=`/path/to/command arg1 arg2`

Examples

## store date command output to $now  ##
now=$(date)

## alternate syntax ##
now=`date`

To display back result (or output stored in a variable called $now) use the echo or printf command:

echo "$now"
printf "%s\n" "$now"

References
https://www.cyberciti.biz/faq/unix-linux-bsd-appleosx-bash-assign-variable-command-output/

Extract substring in Bash

March 3, 2022

echo 'someletters_12345_moreleters.ext' | cut -d'_' -f 2

output

ip route show | grep default | cut -d' ' -f 3

output

178.134.45.216

References
https://stackoverflow.com/questions/428109/extract-substring-in-bash

Tweaks for Firefox

March 3, 2022

Enable Hardware Acceleration

Go to about:preferences
In General, scroll down to Performance
Uncheck the box for Use recommended performance settings
Check the box for Use hardware acceleration when available

Disable Data Collection and Telemetry

Go to about:preferences
Go to Privacy & Security, and scroll down to Firefox Data Collection and Use
Uncheck all boxes in this section
Restart Firefox

Essential About:Config Tweaks

Set browser.download.animateNotifications to False
Set security.dialog_enable_delay to 0
Set network.prefetch-next to False (Only on slow internet connections)
Set browser.newtabpage.activity-stream.feeds.telemetry to false
Set browser.newtabpage.activity-stream.telemetry to false
Set browser.ping-centre.telemetry to false
Set toolkit.telemetry.archive.enabled to false
Set toolkit.telemetry.bhrPing.enabled to false
Set toolkit.telemetry.enabled to false
Set toolkit.telemetry.firstShutdownPing.enabled to false
Set toolkit.telemetry.hybridContent.enabled to false
Set toolkit.telemetry.newProfilePing.enabled to false
Set toolkit.telemetry.reportingpolicy.firstRun to false
Set toolkit.telemetry.shutdownPingSender.enabled to false
Set toolkit.telemetry.unified to false
Set toolkit.telemetry.updatePing.enabled to false

Remove Built-in Firefox Add-ons

In about:config, set reader.parse-on-load.enabled to False
In about:config, set reader.parse-on-load.force-enabled to False
In about:config, set browser.pocket.enabled to False
In about:config, set loop.enabled to False

References
https://www.makeuseof.com/tag/speed-up-firefox-immediately-with-these-6-simple-tweaks/

Connect to Redis in C#

March 1, 2022

var options = ConfigurationOptions.Parse("localhost");
options.Password = "password";
ConnectionMultiplexer redisMultiplexer = ConnectionMultiplexer.Connect(options);

References
https://stackexchange.github.io/StackExchange.Redis/Basics
https://stackexchange.github.io/StackExchange.Redis/Configuration
https://stackoverflow.com/questions/23923247/password-for-redis-with-stackexchange-redis

Configuring a Redis Password

March 1, 2022

sudo nano /etc/redis/redis.conf

# requirepass foobared

Uncomment it by removing the #, and change foobared to a secure password.

sudo systemctl restart redis.service

References
https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-ubuntu-20-04

Create a New User and Grant Permissions in MySQL

March 1, 2022

mysql -u root
# mysql -u root -p

CREATE USER 'newuser'@'localhost' IDENTIFIED BY 'password';

GRANT ALL PRIVILEGES ON * . * TO 'newuser'@'localhost';

ALTER USER 'newuser'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

FLUSH PRIVILEGES;

exit

References
https://www.digitalocean.com/community/tutorials/how-to-create-a-new-user-and-grant-permissions-in-mysql

Secure MongoDB on Ubuntu 20.04

March 1, 2022

mongo

show dbs

use admin

db.createUser({user: "monitoringv5",pwd: "monitoringv5", roles: [ { role: "userAdminAnyDatabase", db: "admin" }, "readWriteAnyDatabase" ]})

exit

sudo nano /etc/mongod.conf

append this line :

security:
  authorization: enabled

sudo systemctl restart mongod

References
https://www.digitalocean.com/community/tutorials/how-to-secure-mongodb-on-ubuntu-20-04

MySQL Error: : ‘Access denied for user ‘root’@’localhost’

March 1, 2022

sudo mysql

-- for MySQL
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'root';

-- for MariaDB
ALTER USER 'root'@'localhost' IDENTIFIED VIA mysql_native_password USING PASSWORD('root');

With a single query we are changing the auth_plugin to mysql_native_password and setting the root password to root and there isn’t any need to restart mysqld or start it with special privileges.

References
https://stackoverflow.com/questions/41645309/mysql-error-access-denied-for-user-rootlocalhost