Category: Linux

Install PHP 7 on CentOS 6
Install EPEP repo with command
```
yum install -y epel-release
```
Next you need REMI repo, you can get it form

https://rpms.remirepo.net/

Install it with
```
rpm -ivh https://rpms.remirepo.net/enterprise/remi-release-6.rpm
```
You can search for PHP versions with command
```
yum search php
```
Select PHP version

First install yum-utils
```
yum install yum-utils
```
Now you can select required PHP version with command
```
yum-config-manager --enable remi-php72
```
Use remi-php70 for PHP 7.0, remi-php71 for PHP 7.1

Install PHP

To install PHP 7.2, run
```
yum install php72 -y
```
PHP binary will be installed as php72, you can create a synlink if you need.
```
ln -s /usr/bin/php72 /usr/bin/php
```
Enable PHP in Apache
```
yum install php72-php
```
Now restart apache
```
service httpd restart
```
php
CentOS 6
March 9, 2018
Firefox

Firefox profile

March 6, 2018

Firefox profile

Here is shortcut i use for my firefox profile

boby@hon-pc-01:~$ cat  ~/.local/share/applications/firefox-vpn.desktop 
[Desktop Entry]
Version=1.0
Name=Firefox VPN
Comment=Browse the World Wide Web
GenericName=Web Browser
Keywords=Internet;WWW;Browser;Web;Explorer
Exec=firefox -P vpn -private-window --class=Firefox-VPN %u
Terminal=false
X-MultipleArgs=false
Type=Application
Icon=go-home
Categories=GNOME;GTK;Network;WebBrowser;
MimeType=text/html;text/xml;application/xhtml+xml;application/xml;application/rss+xml;application/rdf+xml;image/gif;image/jpeg;image/png;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;x-scheme-handler/chrome;video/webm;application/x-xpinstall;
StartupNotify=true
Actions=new-window;new-private-window;

[Desktop Action new-window]
Name=Open a New Window
Exec=firefox -P vpn -new-window

[Desktop Action new-private-window]
Name=Open a New Private Window
Exec=firefox -P vpn -private-window
boby@hon-pc-01:~$

firefox

March 6, 2018

Encrypt
- Encrypting a file using OpenSSL
- Encrypt a file using gpg
March 4, 2018

Encrypting a file using OpenSSL

To encrypt a file, run

openssl enc -aes-256-cbc -in FILE -out FILE.enc

To decrypt, use

openssl enc -d -aes-256-cbc -in FILE.enc -out FILE

You can use -k option to provide password in commend line itself so it won’t prompt for password.

Here is a script i use to take backup

boby@hon-pc-01:~$ cat ~/bin/backup-my-files 
#!/bin/bash

cd $HOME/work/
rm -f myfiles.tar.gz myfiles.tar.gz.openssl
tar --exclude='MY_FILES/.git' -zcvf myfiles.tar.gz MY_FILES
openssl enc -aes-256-cbc -in /home/boby/work/myfiles.tar.gz -out myfiles.tar.gz.openssl

echo "Backup available in folder $HOME/work"
echo "You can decrypt file using"
echo ""
echo "openssl enc -d -aes-256-cbc -in myfiles.tar.gz.openssl -out myfiles.tar.gz"

boby@hon-pc-01:~$

openssl

Encrypt

March 4, 2018

Apache SSL

Here is a non-SSL Apache virtual host.

<VirtualHost *:80>
    ServerName serverok.in
    ServerAdmin admin@serverok.in
    DocumentRoot /home/serverok.in/html
    CustomLog ${APACHE_LOG_DIR}/serverok.in.log combined
    <Directory "/home/serverok.in/html">
        Options All
        AllowOverride All
        Require all granted
        Order allow,deny
        allow from all
    </Directory>
</VirtualHost>

To convert it to SSL VirtualHost, first change the port to 443

Find

<VirtualHost *:80>

Replace with

<VirtualHost *:443>

Add the above Directory entry

SSLEngine on
SSLCertificateFile /etc/ssl/DOMAIN.crt
SSLCertificateKeyFile /etc/ssl/DOMAIN.key

The resulting VirtualHost will look like

<VirtualHost *:443>
    ServerName serverok.in
    ServerAdmin admin@serverok.in
    DocumentRoot /home/serverok.in/html
    CustomLog ${APACHE_LOG_DIR}/serverok.in.log combined
    SSLEngine on
    SSLProtocol all -SSLv2 -SSLv3 -TLSv1 -TLSv1.1
    SSLCertificateFile /etc/ssl/serverok.in.crt
    SSLCertificateKeyFile /etc/ssl/serverok.in.key
    <Directory "/home/serverok.in/html">
        Options All
        AllowOverride All
        Require all granted
        Order allow,deny
        allow from all
    </Directory>
</VirtualHost>

For added security, you can use the following config

SSLEngine on
SSLProtocol             all -SSLv2 -SSLv3 -TLSv1 -TLSv1.1
SSLCipherSuite          ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:!TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384:!TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256:!DSS

Enable mod_ssl

If you get the following error

Invalid command 'SSLEngine', perhaps misspelled or defined by a module not included in the server configuration

You need to enable mod_ssl, to do this, run

On Debian/Apache, run

sudo a2enmod ssl

Restart Apache

sudo service apache2 restart

Force SSL

You can add the following code to Apache virtualhost for the website

Redirect 301 / https://domain.ltd/

ssl

apache

March 4, 2018

time
Timestamp in Bash Script
```
TIME_STAMP="$(date +%Y%m%d-%H%M%S)"
```
for timestamp like 2020-01-23 15:12:45, use
```
TIME_STAMP="$(date "+%Y-%m-%d %H:%M:%S")"
```
For file name
```
date +"%Y-%m-%d-%H-%M-%S"
```
Time stamp in PHP
```
$now = date("Y-m-d-h:i:s");
```
Taking backup
```
mysqldump -u root -p'mv9wCAcDE3CnBV' serverok_wp > ~/serverok_wp-`date +"%Y-%m-%d-%H-%M-%S"`.sql
```
Alaram/stopwatch
- https://kukuklok.com
- https://tools.arantius.com/stopwatch
Time Tracking
- https://www.rescuetime.com
- https://toggl.com
March 3, 2018

ntpdate

ntpdate allows you to update server time with ntp servers.

To install, run

apt install ntpdate

To update server time, run

ntpdate ntp.ubuntu.com

Example

root@ip-172-26-2-47:~# ntpdate ntp.ubuntu.com
 3 Mar 20:32:54 ntpdate[17295]: adjust time server 91.189.91.157 offset -0.000047 sec
root@ip-172-26-2-47:~#

Auto Update Server time with cronjob

Method 1

echo "ntpdate time-a.nist.gov" > /etc/cron.daily/ntpdate
chmod 755 /etc/cron.daily/ntpdate

Method 2

Set following cronjob

30	22	*	*	*	/usr/sbin/ntpdate -b -s 1.pool.ntp.org

time

March 3, 2018

locale-gen
To generate
```
locale-gen en_US.UTF-8
```
If you get error setlocale: LC_ALL: cannot change locale
```
echo "LC_ALL=en_US.UTF-8" >> /etc/environment
echo "LANG=en_US.UTF-8" > /etc/locale.conf
echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen
locale-gen en_US.UTF-8
```
bash: locale-gen: command not found
bash: warning: setlocale: LC_ALL: cannot change locale
language
March 3, 2018

swap

First create a 2 GB file

dd if=/dev/zero of=/swapfile bs=1M count=4096

For 8 GB, use count=8192. You can also use fallocate command instead of dd.

fallocate -l 8G /swapfile

Make it swap

mkswap /swapfile
chmod 0600 /swapfile
swapon /swapfile

Add it to /etc/fstab

echo "/swapfile swap swap defaults 0 0" >> /etc/fstab

swapon

February 27, 2018

DNS Tools
Reverse DNS/rDNS/PTR Record
How to delete Google Cloud DNS Zone

DNS Tools
DNS History
- https://securitytrails.com/ – IP history
- https://completedns.com/dns-history/ – DNS History
DNS Propagation Checker
- https://dnsmap.io – check DNS propogation from differnt countries.
- Whatsmydns.net – check DNS propogation from differnt countries.
- https://dns.google – check DNS propogation from differnt countries.
DNS
DNS Resolver
DNS Errors
- Amazon Route 53 DKIM error
February 27, 2018
Radio

http://libretime.org/

allow you to run your own radio station. It allow you to manage you media, playlists. It support IceCast and Shutcast as media servers.

February 26, 2018

Category: Linux

Force SSL

Alaram/stopwatch

Time Tracking

Auto Update Server time with cronjob

DNS Tools

DNS History

DNS Propagation Checker

DNS

DNS Resolver

DNS Errors