OpenSSL Common Commands

Overview Released in 1998, OpenSSL is a cryptography library available for Linux, Windows, BSD and Mac OS systems. The library allows users to do a variety of tasks such as but not limited to creating CSR’s / private keys, convert certificates to different formats and validiate existing certificates. Over the years I’ve written down commands… Read more »

Blocking Postfix traffic using Fail2ban

So if you are reading this then you have probably seen what appears to be every bot in China connecting to your Postfix server to attempt anything from relaying to auth attacking. Well, have I got the solution for you! Now before you implement this, I will warn you, this is very restrictive, it doesn’t… Read more »

Hardening SSHD for Security

The secure shell daemon should be hardened to prevent unauthorised access before being put into a production environment or exposed to the internet. 1. Verify the /etc/ssh/sshd_config file contains the following lines and that they are not commented out: Protocol 2 IgnoreRhosts yes HostbasedAuthentication no PermitRootLogin no PermitEmptyPasswords no AllowTcpForwarding no (unless needed) X11 Forwarding… Read more »

Encryption of text in images using Steghide (Steganography)

The art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient could understand or view is called Steganography. According to Wikipedia, the word¬†steganography is of Greek origin and means “concealed writing” from the Greek word steganos meaning “covered or protected” and graphei, meaning “writing”…. Read more »