Category: Uncategorized

WordPress HyperDB
HyperDB is a WordPress plugin that allows you to use multiple MySQL database servers with large MySQL installations. It is used to WordPress.com to distribute MySQL server load amount multiple MYSQL database servers hosted in different data centers.

HyperDB supports
- Read and write servers (replication)
- Configurable priority for reading and writing
- Local and remote datacenters
- Private and public networks
- Different tables on different databases/hosts
- Smart post-write master reads
- Failover for downed host
- Advanced statistics for profiling
- WordPress Multisite
You can find more about the HyperDB plugin at

https://wordpress.org/plugins/hyperdb/

How it works

HyperDB replaces WordPress wpdb class so it can read from multiple MySQL database servers.

On a default WordPress installation, when a website grows, you need to upgrade the server to a more powerful server, but there is a limit on this as at some point upgrading server becomes costly. What you can do is move MySQL into its own dedicate server. For larger WordPress sites, a single dedicated MySQL server is not enough. In such a case, you can set up MySQL replication. When you set up MySQL replication with read-only nodes, you can only write to “main” MySQL server, all Database reads can be distributed across multiple MySQL read-only replicas. HyperDB checks each MySQL query, detect if it is a read or write/update query. If read, it is sent to one of the read-only MySQL replica servers.

See WordPress
July 8, 2021
Warning: Use of undefined constant OAUTH_REQENGINE_CURL
On an Ubuntu server (Ubuntu 20.04.2 LTS) when running a PHP script, I get the following error.
```
Warning: Use of undefined constant OAUTH_REQENGINE_CURL - assumed 'OAUTH_REQENGINE_CURL' (this will throw an Error in a future version of PHP
```
On checking phpinfo, I get
```
Request engine support	php_streams
```
curl is missing in “Request engine support”.

This is because the default php-oauth package does not support curl. To fix, uninstall php-oauth and install oauth package using pecl.

Uninstall pcel
```
apt install php-oauth -y
```
install curl dev package
```
apt install libcurl4-gnutls-dev
ln -s /usr/include/x86_64-linux-gnu/curl /usr/include/curl
```
Install PHP PECL
```
apt install php-pear
```
Install oAuth
```
pecl install oauth
```
Edit php.ini file
```
vi /etc/php/7.4/cli/php.ini
```
Add at end of the file
```
extension=oauth.so
```
You need to do the same for Apache and php-fpm php.ini files located at
```
/etc/php/7.4/apache2/php.ini
/etc/php/7.4/fpm/php.ini
```
7.4 is for PHP version 7.4. Change this to whatever PHP version you have on your server. After making the change, phpinfo() page shows curl

See php
June 26, 2021
SaaS

https://www.paddle.com – Payment processing for SaaS.

June 21, 2021

Enable SSL in Haproxy Docker Container

I have a haproxy container running on port 80. This container is started with command

docker run -d -p 80:80 --name haproxy1 -v /home/ubuntu/haproxy:/usr/local/etc/haproxy:ro haproxy:1.7

This haproxy used following configuration file /home/ubuntu/haproxy/haproxy.cfg

global

defaults

frontend sok-front-end
    bind *:80
    mode http
    default_backend sok-front-end

backend sok-front-end
    mode http
    balance roundrobin
    server srv3 172.17.0.2:8000

To make this haproxy work with SSL, first create a ssl.pem file with your SSL certificate contents in following order

1) Your Private Key
2) Your SSL CRT
4) CA-BUNDLE

copy and paste all those certs into ssl.pem file inside /home/ubuntu/haproxy/ssl.pem

Now modify your /home/ubuntu/haproxy/haproxy.cfg file as follows

global

defaults

frontend sok-front-end
    bind *:80
    bind :::443 ssl crt /usr/local/etc/haproxy/ssl.pem
    acl https ssl_fc
    http-request set-header X-Forwarded-Proto http  if !https
    http-request set-header X-Forwarded-Proto https if https
    mode http
    default_backend sok-front-end

backend sok-front-end
    mode http
    balance roundrobin
    server srv3 172.17.0.2:8000

Now we need to stop current docker container as it only allow port 80 to be shared.

docker container stop haproxy1

Lets create a new haproxy container with port 443 forwaded.

docker run -d -p 80:80 -p 443:443 --name haproxy2 -v /home/ubuntu/haproxy:/usr/local/etc/haproxy:ro haproxy:1.7

See Haproxy

June 27, 2020

PHP script to monitor exim mail queue
When you run exim mail server, it is good to keep an eye on number of emails in mail queue. here is a PHP script that will check number of emails in queue, if it exceed pre-set number, it will email you.

Create file
```
mkdir /usr/serverok/
vi /usr/serverok/mail_q_monitor.php
```
Add following content.
```
 $alertOn) {
    $hostname = exec('/bin/hostname');
    $subject = 'Mail queue alert on ' . $hostname;
    $mail_text = 'Mail queue on server ' . $hostname . ' have ' . $num_mails . ' mails';
    mail($adminEmail, $subject, $mail_text);
}
```
In this case, if mails in queue exceeded 100, you get email.
```
$alertOn = 100;
```
You can change 100 to whatever number you need.
```
$adminEmail = "you@your-domain.com";
```
Replace you@your-domain.com with your email address.

Set script to run every 10 minutes using cronjob
```
*/10 * * * * /usr/local/bin/php /usr/serverok/mail_q_monitor.php >/dev/null 2>&1
```
August 26, 2019

Install SSL on Centova Cast

Edit file

vi /usr/local/centovacast/etc/cc-panel.conf

Find

listen 2199 default ssl;

Add below

listen 443 ssl;
listen 80;

Restart Centova Cast

/usr/local/centovacast/centovacast restart

At this point, you will be able to access Centova Cast on port 80 at

http://YOUR_SERVER_IP/login/index.php

To install LetsEncrypt Free SSL certificate, run

/usr/local/centovacast/sbin/setssl letsencrypt YOUR-DOMAIN.EXTN

Restart Centova Cast

/usr/local/centovacast/centovacast restart

Now you will be able to access Centova Cast using HTTPS.

November 22, 2018

VestaCP Installer Compromised

VestaCP Free Hosting control panel compromised again. Hackers where able to get access to VestaCP infrastcuture server, allowing them to modify installation script, so it sent root password of servers to hacker.

Here is post from VestaCP on their forum

I’m sorry about inactivity in this post from our side. It was a complex issue and we were not sure we understand the whole picture. Leak in the installer is just one piece of the puzzle. All pieces together lead to cumulative effect.

The issue number one

Our infrastructure server was hacked. Presumably using API bug in the release 0.9.8-20. The hackers then changed all installation scripts to log admin password and ip as addition to the distro name we used to collect stats.

Please check if your server IP here

http://vestacp.com/test/?ip=127.0.0.1

If it’s there you should change admin passwords as soon as possible. Also please make sure there is no /usr/bin/dhcprenew binary installed on your server. This binary is some sort of trojan that is able to launch remote DDoS attack or open shell to your server

For more information, see

https://forum.vestacp.com/viewtopic.php?f=10&t=17641&start=180#p73907

October 21, 2018
Change PHP version for a site in Plesk Command line
To change PHP version for a site, first find available PHP handlers, this can be done with command
```
/usr/local/psa/admin/bin/php_handlers_control --list
```
You need to find the id for the PHP handler. For PHP 5.6 fpm, it is “plesk-php56-fpm”.

To change a sites PHP version to PHP 5.6, run
```
plesk bin domain -u DOMAIN_NAME_HERE -php_handler_id plesk-php56-fpm
```
Example
October 4, 2018

error: ‘x264_bit_depth’ undeclared (first use in this function)

When installing ffmpeg, i get error

CC	libavcodec/libvorbisenc.o
CC	libavcodec/libx264.o
libavcodec/libx264.c: In function ‘X264_frame’:
libavcodec/libx264.c:282:9: error: ‘x264_bit_depth’ undeclared (first use in this function)
     if (x264_bit_depth > 8)
         ^
libavcodec/libx264.c:282:9: note: each undeclared identifier is reported only once for each function it appears in
libavcodec/libx264.c: In function ‘X264_init_static’:
libavcodec/libx264.c:892:9: error: ‘x264_bit_depth’ undeclared (first use in this function)
     if (x264_bit_depth == 8)
         ^
make: *** [libavcodec/libx264.o] Error 1

This is due to incompatability with ffmpeg and x264.

What you can do is try another version of x264. You will be able to download older version of x264 from

ftp://ftp.videolan.org/pub/x264/snapshots

On 2018-08-14, it failed with latest stable snapshot. So i tried 14 days old stable snapshot

cd /usr/local/src/
wget ftp://ftp.videolan.org/pub/x264/snapshots/x264-snapshot-20180730-2245-stable.tar.bz2
tar xvf x264-snapshot-20180730-2245-stable.tar.bz2
cd /usr/local/src/x264-snapshot-20180730-2245-stable
make clean && make distclean
./configure --prefix=/usr --enable-shared
make && make install
ldconfig

This worked with ffmpeg.

Solution here is to try latet version first, if it did not work, try older version, say try 1 month old version, if that did not work, go back 2 months, see if that works.

Now install ffmpeg with

cd /usr/local/src/
wget https://github.com/FFmpeg/FFmpeg/archive/n3.3.5.tar.gz
tar zxf n3.3.5.tar.gz
cd /usr/local/src/FFmpeg-n3.3.5/
ldconfig
make clean && make distclean
./configure --prefix=/usr --enable-shared --enable-libxvid --enable-libvorbis --enable-libtheora --enable-libmp3lame --enable-gpl --enable-libfdk-aac --enable-nonfree --enable-libx264 --enable-libfreetype
make && make install && ldconfig

August 14, 2018

Enable Zend OPcache in PHP
To enable Zend OPCache in PHP, edit php.ini add following to end of the file
```
zend_extension=opcache.so
```
Now you may need to adjust some settings, in php.ini uncomment following, change values as needed.
```
opcache.enable=1
opcache.enable_cli=1
opcache.memory_consumption=128
opcache.max_accelerated_files=10000
opcache.validate_timestamps=1
opcache.revalidate_freq=10
```
Verify it with
```
[root@vps154294 php]# php -m | grep  Zend
Zend OPcache
[Zend Modules]
Zend OPcache
[root@vps154294 php]# 
```
Restart web server. If you using php-fpm or fcgi, you need to restart the process.

phpinfo() will show
December 10, 2017

Install Redis PHP Module from source

To install Redis PHP module from source, run

cd /usr/local/src
git clone https://github.com/phpredis/phpredis.git
cd /usr/local/src/phpredis
/usr/serverok/php-7.1.12/bin/phpize
./configure --with-php-config=/usr/serverok/php-7.1.12/bin/php-config
make && make install

Once installed, edit your php.ini file, add following below extension_dir line

extension=redis.so

Verify redis is installed with php -m

[root@vps154294 ~]# /usr/serverok/php-7.1.12/bin/php -m | grep redis
redis
[root@vps154294 ~]#

Now restart web server

service httpd restart

phpinfo() will show following

phpinfo redis

December 10, 2017

Reset osticket admin password
Reset password for admin, can be used for any user, replace admin with username.
```
UPDATE `ost_staff` SET `passwd` = MD5( 'newpassword' ) WHERE `username` = 'admin';
```
See osticket
October 12, 2011

Category: Uncategorized

How it works