Blog

How to Auto restart elasticsearch with monit

monit is a program used to monitor processes and restart them if they failed. If your server don’t have monit installed, see install instructions at Install Monit on Ubuntu or Install Monit on CentOS

To restart elasticsearch on failure, create a file

vi /etc/monit/conf-enabled/elasticsearch.conf

Add the following content to the file

check process elasticsearch with pidfile "/var/run/elasticsearch/elasticsearch.pid"
   start program = "/bin/systemctl start elasticsearch"
   stop  program = "/bin/systemctl stop elasticsearch"

Reload monit with

monit reload

To check the status of monit, run

monit status

Example

root@sok:~# monit status
Monit 5.26.0 uptime: 8m

Process 'elasticsearch'
  status                       OK
  monitoring status            Monitored
  monitoring mode              active
  on reboot                    start
  pid                          366866
  parent pid                   1
  uid                          115
  effective uid                115
  gid                          118
  uptime                       6m
  threads                      60
  children                     1
  cpu                          -
  cpu total                    -
  memory                       58.0% [2.2 GB]
  memory total                 58.2% [2.2 GB]
  security attribute           unconfined
  disk read                    0 B/s [97.5 MB total]
  disk write                   0 B/s [2.3 MB total]
  data collected               Mon, 09 Aug 2021 10:07:22

System 'sok.guest'
  status                       OK
  monitoring status            Monitored
  monitoring mode              active
  on reboot                    start
  load average                 [0.02] [0.18] [0.47]
  cpu                          4.4%us 1.4%sy 0.1%wa
  memory usage                 3.1 GB [81.7%]
  swap usage                   774.5 MB [18.9%]
  uptime                       3d 22h 39m
  boot time                    Thu, 05 Aug 2021 11:28:16
  data collected               Mon, 09 Aug 2021 10:07:22

root@sok:~#

To see other ways of restarting ElasticSearch, see How to auto restart ElasticSearh service on failure

Back to monit

August 9, 2021

imunify get list of all infected files
imunify store data in SQLite database. To see a list of malware infected files, start sqllite with
```
sqlite3 /var/imunify360/imunify360.db
```
Data is stored in table malware_hits.

To find the schema of the table, run
```
.schema malware_hits
```
We only want to orig_file column from the table, so run the SQL command
```
select orig_file from malware_hits;
```
Delete all past scan results

If you need to clean all past scan results, then first stop imunify
```
systemctl stop imunify-antivirus
```
Start sqlite
```
sqlite3 /var/imunify360/imunify360.db
```
Delete data from the tables
```
DELETE FROM malware_history;
DELETE FROM malware_hits;
DELETE FROM malware_scans;
```
Exit from sqlite command prompt and start imunify
```
systemctl start imunify-antivirus
```
August 8, 2021
How to Create Custom 404 Error Page in Apache
A 404 error happens when a visitor comes to your website and the page requested is not found on your website. This happens when a link changed and some other pages or websites still link to your old web page URL.

When “HTTP/1.1 404 Not Found” error occurs, web servers show a basic error message saying the page is not found on the server. Most visitors will leave your website when this happens. A properly built custom 404 page allows your site to engage the visitor, present them useful information, so they stay on the website, explore other pages instead of leaving the website.

It is good practice to track 404 errors, set a 301 redirect for these pages to the proper destination, so your site visitors can find whatever they are looking for with fewer efforts.

To create a custom 404 error page in the Apache web server, create a .htaccess file with the following content
```
ErrorDocument 404 /404.html
```
Create an HTML page with your custom 404 error message, save it as 404.html.

Now when you access a page that is not present on your website, you will see this custom 404 error page.

See htaccess
August 5, 2021

Temperature

To find CPU Temperature, run command sensors

sensors

Example

boby@sok-01:~$ sensors
k10temp-pci-00c3
Adapter: PCI adapter
Vcore:       925.00 mV 
Vsoc:          1.06 V  
Tctl:         +36.2°C  
Tdie:         +36.2°C  
Icore:         4.00 A  
Isoc:          1.75 A  

boby@sok-01:~$

To find the temperature of NVIDIA graphics card, run

/usr/bin/nvidia-smi -q -d temperature

Example

boby@sok-01:~$ /usr/bin/nvidia-smi -q -d temperature

==============NVSMI LOG==============

Timestamp                                 : Mon Aug  2 23:53:27 2021
Driver Version                            : 460.91.03
CUDA Version                              : 11.2

Attached GPUs                             : 1
GPU 00000000:01:00.0
    Temperature
        GPU Current Temp                  : 45 C
        GPU Shutdown Temp                 : 97 C
        GPU Slowdown Temp                 : 94 C
        GPU Max Operating Temp            : 92 C
        GPU Target Temperature            : 83 C
        Memory Current Temp               : N/A
        Memory Max Operating Temp         : N/A

boby@sok-01:~$

August 2, 2021

sensors
sensors command shows data from various sensors on your computer like CPU temperature, voltage, etc…

To install lm-sensors package, run
```
apt install lm-sensors
```
To see sensor data, run the command “sensors”.
```
boby@sok-01:~$ sensors
k10temp-pci-00c3
Adapter: PCI adapter
Vcore:       844.00 mV 
Vsoc:          1.06 V  
Tctl:         +39.0°C  
Tdie:         +39.0°C  
Icore:         5.00 A  
Isoc:          1.50 A  

boby@sok-01:~$ 
```
To properly configure sensors, you need to run
```
sudo sensors-detect
```
This only needs to run one time to detect your hardware configuration. It will ask many questions, press enter to use default values.
August 2, 2021

ss

ss is a tool to investigate sockets. It is similar to netstat, but shows more information. To see list of all open ports, run

ss -tlnp

Example

boby@sok-01:~$ sudo ss -lntp
State   Recv-Q  Send-Q    Local Address:Port     Peer Address:Port  Process                                                                                                                                
LISTEN  0       128           127.0.0.1:7878          0.0.0.0:*      users:(("ssh",pid=2401,fd=5))                                                                                                         
LISTEN  0       80            127.0.0.1:3306          0.0.0.0:*      users:(("mysqld",pid=1135,fd=19))                                                                                                     
LISTEN  0       4096            0.0.0.0:111           0.0.0.0:*      users:(("rpcbind",pid=880,fd=4),("systemd",pid=1,fd=34))                                                                              
LISTEN  0       511             0.0.0.0:80            0.0.0.0:*      users:(("nginx",pid=1147,fd=10),("nginx",pid=1146,fd=10),("nginx",pid=1145,fd=10),("nginx",pid=1144,fd=10),("nginx",pid=1143,fd=10))  
LISTEN  0       32        192.168.122.1:53            0.0.0.0:*      users:(("dnsmasq",pid=1528,fd=6))                                                                                                     
LISTEN  0       4096      127.0.0.53%lo:53            0.0.0.0:*      users:(("systemd-resolve",pid=883,fd=13))                                                                                             
LISTEN  0       5             127.0.0.1:631           0.0.0.0:*      users:(("cupsd",pid=929,fd=7))                                                                                                        
LISTEN  0       511           127.0.0.2:443           0.0.0.0:*      users:(("nginx",pid=1147,fd=11),("nginx",pid=1146,fd=11),("nginx",pid=1145,fd=11),("nginx",pid=1144,fd=11),("nginx",pid=1143,fd=11))  
LISTEN  0       1               0.0.0.0:7070          0.0.0.0:*      users:(("anydesk",pid=1054,fd=32))                                                                                                    
LISTEN  0       128               [::1]:7878             [::]:*      users:(("ssh",pid=2401,fd=4))                                                                                                         
LISTEN  0       4096               [::]:111              [::]:*      users:(("rpcbind",pid=880,fd=6),("systemd",pid=1,fd=36))                                                                              
LISTEN  0       5                 [::1]:631              [::]:*      users:(("cupsd",pid=929,fd=6))                                                                                                        
boby@sok-01:~$

See netstat

July 29, 2021

How to install development tools on Debian/Ubuntu
Development tools are programs used to build software from its source code. These include compilers, make, and other generally used libraries.

To install development tools on Ubuntu/Debian, run
```
apt install -y build-essential
apt install -y autoconf automake gdb libffi-dev zlib1g-dev libssl-dev git wget
```
See Ubuntu, Debian
July 28, 2021
Create a Debian Container in LXD
Debian OS templates are available in images:debian/VERSION. To see all available Debian OS templates, run
```
lxc image list images: debian
```
To create a container with Debian 10 OS, run
```
lxc launch  images:debian/10 my-debian
```
Example

Create alphine linux container
```
lxc launch images:alpine/3.22 test-alpine
```
To list all available alphone container versions, use
```
lxc image list images: alpine
```
See LXD
July 28, 2021
Audacity

Audacity Import Filter Curve in Ubuntu

July 24, 2021

Audacity Import Filter Curve in Ubuntu

The import feature in Audacity Filter Curve Plugin is disabled on Ubuntu. Save feature worked. So what I did was to save a preset, then edit it, replace it with the preset you need.

To import Josh Meyer’s Male EQ preset available at

https://drive.google.com/file/d/163aSM4c-I6REKDqIzD9IzwiyDR4cXqma/view

First saved one of the preset. It asked for a name, I enter “sevrerok” as the preset name.

Close Audacity, Edited the file

/home/boby/.audacity-data/pluginsettings.cfg

Find the entry like

[pluginsettings/base64\:RWZmZWN0X0F1ZGFjaXR5X0F1ZGFjaXR5X0ZpbHRlciBDdXJ2ZQ\=\=/private/UserPresets/serverok]

Below this, you can add your preset. Here is what I have in the pluginsettings.cfg file

[pluginsettings/base64\:RWZmZWN0X0F1ZGFjaXR5X0F1ZGFjaXR5X0ZpbHRlciBDdXJ2ZQ\=\=/private/UserPresets/serverok]
Parameters=f0="62.77682" f1="70.002037" f10="336.65327" f11="492.91565" f12="591.0509" f13="689.68267" f14="776.07428" f15="889.28813" f16="982.67802" f17="9948.9608" f18="11195.196" f19="12597.538" f2="73.252718" f20="14047.435" f21="16096.677" f3="83.938837" f4="97.946153" f5="119.59827" f6="152.81833" f7="195.26572" f8="221.72906" f9="256.39197" FilterLength="8191" InterpolateLin="0" InterpolationMethod="B-spline" v0="-41.952381" v1="-10.904762" v10="0.031745911" v11="-2.984127" v12="-1.3650789" v13="-0.015872955" v14="0.469841" v15="0.469841" v16="-0.015872955" v17="-0.015872955" v18="-0.031746864" v19="-0.031746864" v2="-5.2349215" v20="-1.7301588" v21="-41.885715" v3="-1.6888895" v4="0.13650751" v5="1.1746035" v6="2" v7="2" v8="1.3015871" v9="0.031745911"

July 24, 2021

How to uninstall the PowerShell Module?
To uninstall a PowerShell module use the Uninstall-Module command. The module should not be in use to uninstall it.
```
Uninstall-Module -Name MODULE_NAME_HERE
```
To force uninstall a module run
```
Uninstall-Module -Name MODULE_NAME_HERE -Force -Verbose
```
To uninstall all versions of a module, use option -AllVersions
```
Uninstall-Module -Name MODULE_NAME_HERE -AllVersions -Force -Verbose
```
If you need to keep a version and uninstall all other versions, run
```
Uninstall-Module -Name MODULE_NAME_HERE -RequiredVersion 2.1.2 -Force -Verbose
```
July 22, 2021
ACME (acme.sh) Free SSL Certificate
ACME (acme.sh) is a shell script for generating LetsEncrypt SSL certificate. acme.sh is written in bash, so it works on any Linux server without special requirements. For getting SSL, another popular option is to use certbot.
To install, run
```
cd /usr/local/src
git clone https://github.com/acmesh-official/acme.sh.git
cd ./acme.sh
./acme.sh --install -m admin@serverok.in
source ~/.bashrc
```
When you install, it will set a daily cronjob for auto SSL renewal. You can see it with “crontab -l” command.

Set acme.sh to use LetsEncrypt SSL (Defaul is ZeroSSL)
```
acme.sh --set-default-ca --server letsencrypt
```
Set to ZeroSSL, run
```
acme.sh --set-default-ca --server zerossl
```
To issue an SSL certificate, run
```
acme.sh --issue -d example.com -d www.example.com -w /home/example.com/html/
```
Standalone mode (nginx)
```
acme.sh  --issue  -d example.com  --standalone --pre-hook "systemctl stop nginx" --post-hook "systemctl restart nginx"
```
Using non-standard port
```
acme.sh  --issue  -d example.com  --standalone --httpport 88
```
For more ways to issue SSL certificates, see

https://github.com/acmesh-official/acme.sh/wiki/How-to-issue-a-cert

Install SSL Certificate

To install the SSL certificate, run
```
acme.sh --install-cert -d DOMAIN_NAME \
--fullchain-file /etc/ssl/DOMAIN_NAME.crt \
--key-file /etc/ssl/DOMAIN_NAME.key \
--reloadcmd "systemctl restart nginx"
```
For Apache
```
acme.sh --install-cert -d DOMAIN_NAME \
--cert-file /etc/ssl/DOMAIN_NAME.crt \
--key-file /etc/ssl/DOMAIN_NAME.key \
--fullchain-file /etc/ssl/DOMAIN_NAME.ca \
--reloadcmd "service apache2 force-reload"
```
If you use Apache, replace “service nginx force-reload” with “service apache2 force-reload”. For CentOS/RHEL, use httpd instead of apache2.

You can find how to enable SSL on Nginx server at Configure Nginx Server with SSL, For Apache web server, see Configure Apache Webserver with SSL

See LetsEncrypt
July 20, 2021

Blog

Delete all past scan results

Install SSL Certificate