Developers Technical Tutorials

Set Up DKIM, SPF and Reverse DNS to Improve Mail Deliverability

By Mike Goh May 14, 2020Developers Technical TutorialsNetwork, SecurityNo Comments

Introduction DomainKeys Identified Mail (DKIM) is a protocol that contributes to DMARC compliance and requests the sender origin to take responsibility for sent messages that can be verified by mailbox providers. Essentially, it enables the outbound domain to digitally sign…

Host Multiple Websites with jwilder nginx-proxy and letsencrypt-companion

By Mike Goh May 8, 2020Developers Technical TutorialsDocker, Web1 Comment

Introduction Two years ago, in 2018, I was introduced to Docker by a colleague of mine who was a brilliant programmer. Thus, I started my Docker journey on my own by reading tutorials online. I was developing a WordPress website…

How to Merge Server-side and Docker iptables Firewall Rules

By Mike Goh April 30, 2020Developers Technical TutorialsDocker, SecurityNo Comments

Introduction Docker is widely used to place applications in containers. One of the reasons why Docker is so popular is because of security thanks to its isolation capabilities. For example, it allows you to isolate applications from each other. Installing…

Host Website on IPv6 NAT VPS with Cloudflare DNS and NGINX

By Mike Goh April 26, 2020Developers Technical TutorialsServers, WebNo Comments

Introduction Cloud services like AWS, DigitalOcean and lesser-known VPS hosting providers sell VM (Virtual Machines). The annual price can range from $20 (less-known providers) to $70 for cloud services like AWS. All VM plans come with 1 dedicated IPv4 address…

How to Resolve iptables: No chain/target/match by that name

By Mike Goh April 24, 2020Developers Technical TutorialsCommand Line, SecurityNo Comments

Introduction If you encounter such error, it means that the CONFIG_NETFILTER module was not complied in your kernel. All VPS (virtual private server) that I owned from DigitalOcean, AWS, Google Cloud and other lesser-known host providers have it by default…

Change Port and Disallow Root Login to Secure SSH Server

By Mike Goh April 24, 2020Developers Technical TutorialsSecurity, ServersNo Comments

When you subscribe to a Linux VPS (Virtual Private Server) from any host providers, the default firewall rule is to accept all incoming connections to any ports hence you can connect via Port 22 using a SSH telnet client like…

How to Secure Server with Firewall using iptables

By Mike Goh April 23, 2020Developers Technical TutorialsSecurity, ServersNo Comments

iptables is a command-line firewall utility that allows a system administrator to configure the IP packet filter rules made possible by the Netfilter modules complied into the Linux Kernel. The rules are kept to a bare minimum on the firewall…

How to Backup Databases and Files, Rotate and Rsync to Remote

By Mike Goh April 19, 2020Developers Technical TutorialsBackup, Command LineNo Comments

We should always schedule backups for our website files and databases but should never keep the backups only in the server which your websites and databases reside in. If you are on solid cloud providers like Amazon Web Services (AWS)…

What is Clickjacking and How to Prevent It

By Mike Goh April 18, 2020Developers Technical TutorialsSecurity, WebNo Comments

Clickjacking, according to Wikipedia, is a malicious technique of tricking a user into clicking on something different from what the user perceives, thus potentially revealing confidential information or allowing others to take control of their computer while clicking on seemingly…

How to Backup WordPress Database and Directory Docker Containers

By Mike Goh April 16, 2020Developers Technical TutorialsBackup, DockerNo Comments

In this tutorial, I am going to show you how to backup Docker containers for services WordPress and MySQL in a docker-compose.yml file. If you read enough backup articles like me, you will find that some articles relate to just…

Set Up DKIM, SPF and Reverse DNS to Improve Mail Deliverability

Host Multiple Websites with jwilder nginx-proxy and letsencrypt-companion

How to Merge Server-side and Docker iptables Firewall Rules

Host Website on IPv6 NAT VPS with Cloudflare DNS and NGINX

How to Resolve iptables: No chain/target/match by that name

Change Port and Disallow Root Login to Secure SSH Server

How to Secure Server with Firewall using iptables

How to Backup Databases and Files, Rotate and Rsync to Remote

What is Clickjacking and How to Prevent It

How to Backup WordPress Database and Directory Docker Containers

Asus Router Setup – Wifi Settings

How to Resolve iptables: No chain/target/match by that name

Create Helpdesk Ticketing System with Google Apps Script

Host Multiple Websites with jwilder nginx-proxy and letsencrypt-companion