Security

Set Up SFTP Chroot Jail using OpenSSH

By Mike Goh July 29, 2022Developers Technical TutorialsCommand Line, SecurityNo Comments

Introduction You may want to use one of your existing servers as a SFTP server without subscribing to another EC2 instance. Or you would like to have multiple SFTP users/vendors on a single SFTP server to save on resources and…

VeraCrypt Drive Encryption to Protect Data

By Mike Goh June 15, 2020Software and Web Services ReviewsSecurity, SoftwareNo Comments

Introduction TrueCrypt is the first on-the-fly encryption (OTFE) that I used and when it got discontinued, I switched to VeraCrypt. Similar to TrueCrypt, VeraCrypt is a small encryption software that is used for OTFE and is a fork of the…

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

By Mike Goh May 14, 2020Developers Technical TutorialsEmail, 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…

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…

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…

What is Clickjacking and How to Prevent It

By Mike Goh April 18, 2020Developers Technical TutorialsNGINX, SecurityNo 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…

Learned a New Word Today – ‘Clickjacking’

By Mike Goh April 17, 2020Daily Rants and Excitement BlogSecurityNo Comments

Recently, I received an email from my supervisor asking me to do an assessment on a bug. The whole story unfolded as I scrolled down the email conversation. It was a web security vulnerability actually and it was originally reported…

Set Up SFTP Chroot Jail using OpenSSH

VeraCrypt Drive Encryption to Protect Data

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

How to Merge Server-side and Docker iptables Firewall Rules

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

What is Clickjacking and How to Prevent It

Learned a New Word Today – ‘Clickjacking’

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

Asus Router Setup – Wifi Settings

Create Helpdesk Ticketing System with Google Apps Script

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