Dev Notes

Various Cheat Sheets and Resources by David Egan/Carawebs.

This website contains notes & cheatsheets for web development, Linux systems administration, information security and cryptocurrency.

This site is maintained by David Egan:

Highlighted Posts

Radix 64 Encoding: Implementation in C

21 Aug 2018

Radix 64 or base 64 is a binary-to-text encoding system that is designed to allow binary data to be represented in ASCII string format. This is an educational project accepts a string from a user and Radix 64 encodes it.

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First & Last Element in C++ Iterator Loop

19 Jul 2018

When looping with an iterator, the index of the current iteration isn't immediately obvious unless you resort to incrementing a counter. Fortunately it's easy to find the start and end of your loop.

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HTTP Server in C

12 Jun 2018

Simple http server socket in Linux. This is an educational work in progress, and these are my notes.

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List & Dict Comprehensions in Python

27 May 2018

Python comprehensions are syntactic sugar constructs that provide a way to build a list, dictionary or set from a starting list, dictionary or set whilst altering or filtering elements.

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Javascript Resources

01 Apr 2018

Collection of resources for learning Javascript.

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Define User Input From an Integer List in C++

04 Feb 2018

There are many ways to collect user input. In this example a user is prompted to make a selection from a numbered list. This sets the int choice variable, which can then be used to control programme flow.

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Encrypted Backup Drive in Ubuntu Xenial 16.04

15 Oct 2017

Protect your sensitive data - create a LUKS encrypted backup partition for Ubuntu 16.04 Xenial Xerus that is automatically mounted on boot.

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Bitcoin Cold Wallet Setup Bash Script

22 Aug 2017

Access a Bitcoin core wallet in an airgapped environment. Secure management of cold-wallets.

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Ignore IP Addresses in Fail2Ban

20 Jul 2017

Fail2Ban can help protect your Linux server from attack. It's a Python package that monitors log files and dynamically adjusts firewall rules to block malicious IP addresses. This article shows how to configure Fail2Ban so that specified IP addresses are ignored.

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Install and Run Geth (golang implemenation of Ethereum) on Ubuntu

03 Jul 2017

Ethereum is a decentralized blockchain-based platform that runs smart contracts. Because of the decentralized nature of Ethereum, smart contracts run exactly as programmed - short of an internet apocalypse, there is no possibility of downtime, censorship, fraud or third-party interference. The network is cryptographically secure, decentralized and tamper-proof.

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Verification of Bitcoin Core Download in Ubuntu

01 Jul 2017

Install Bitcoin Core in Ubuntu 16.04 - how to download and verify from

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Enable all Apache Config Files

22 Jun 2017

Enable all Apache virtual host configurations at once. This article provides a useful BASH script that loops through and enables all vhost configs - useful when setting up new development machines or changing servers.

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Laravel 5.4 and MariaDB Errors

28 May 2017

When running migrations on Laravel 5.4 and MariaDB you may encounter an error related to the permitted maximum length of keys - "1071 Specified key was too long; max key length is 767 bytes" Fortunately, there's an easy fix.

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Apache Server Security on Ubuntu 16.04 Xenial

22 May 2017

This article lists some sensible configuration defaults for Apache 2.4 on a Ubuntu 16.04 server. It explains how to apply these globally at the server level.

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WordPress Reserved Terms and Post Requests

17 May 2017

When submitting a form to a WordPress site, there are a number of reserved keywords that should not be used as name attributes - including “name”, “author” and “type”. Using such keywords may result in odd errors - either unexplained 404 errors or the template reverting to the index.php template.

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