A collection of 18 posts

Jan 2, 2019

OpenWRT/LEDE Bridging Firewall

It would be neat if my wireless access point could bridge directly to my cable modem so that clients would have proper public IP addresses. Being directly connected to the internet significantly increases vulnerability so the aim is to address this with a bridge firewall.

Dec 27, 2018

Bash port scanner

The script, using only Bash, will scan common ports, and if an open port is found, it will display a base64 encoded output of the servers response.

Dec 19, 2018

Reactive malware blocking with ipset

This tutorial will demonstrate how to create reactive firewall rules. If a device attempts to communicate with known malware command-and-control servers, the potentially compromised device will be added to a blacklist, and its internet access will be immediately disabled.

Dec 9, 2018

Per-User VPN Routing

This tutorial will show how to route all the traffic belonging to particular user account through an OpenVPN tunnel

Jan 21, 2018

Customizing Digitalocean Floating IPs

Digitalocean allows, for free, the option to add an additional IP address to your virtual machine ("droplet"). These floating IPs are similiar to Amazon AWS Elastic IPs and are tied to

Dec 15, 2017

Routeable Loopback Addresses

Today we will learn about loopback addresses that can be reached from the outside via routing. This is useful for running services on a router In a previous post, I talked about the

Nov 26, 2017

Using Ferm to sweeten IPTables

Ferm is a 'frontend' for iptables written in Perl. The best way to describe it is a firewall compiler (although it can do more than that, as we'll see later). Ferm provides a syntax that is simple, rich, and flexible for writing rules, ferm then generates a list of iptables rules.

Nov 21, 2017

Comprehensive OpenVPN Tutorial

In this tutorial, we will look at managing an openvpn server and certificate authority and will provide a detailed breakdown of the configuration options Table of contents Setting up a CA Build the

Jul 11, 2017

My IPTables Configuration Script

I've talked quite a lot about iptables but haven't really shown how I actually put it into practice. Today I'll share a shell script I wrote to set up IPTables on my Fedora

Feb 14, 2017

IPtables: Constructing user chains

Now that we are familiar with how iptables is organized we can start defining our own chains. This allows for greater control, flexibility, and in some cases, better efficiency. The most profound efficiency

Dec 13, 2016

Dynamic Rules with IPSet

Wouldn't it be good if port scanning IPs could trigger a rule that adds themselves to a 'known offenders' firewall list? Wouldn't it be good if you could combine white and black ACLs