I kept finding strange things in my log files and I wanted an automated way of going through them and banning IPs that are trying weird stuff. The answer in this case was fail2ban and the example that I’m covering in this post is looking out for and banning IPs attempting to use my mail server as an open relay. Continue reading “Getting the hang of fail2ban”
If you want a personal VPN solution that you can host at home or on a VPS, PPTP is the easiest way to do it. Or if you want a VPN test subject, PPTP is also the easiest way to do it. The following will detail how to set up a PPTP server on a Debian (version 7.8) machine. To be understood that choosing PPTP as a VPN doesn’t guarantee a really secure solution , but it can save time and setup issues associated with other alternatives. For a more secure alternative over PPTP, I’d recommend OpenVPN. Continue reading “Setting up and debugging a PPTP server on Debian”
The Linux crontab is relatively easy to understand. Still, it can generate a lot of frustration when debugging or even when creating an entry. In the present article I have gathered resources and information that I’ve used over the time when playing with cronjobs.
The present article describes how to use mail encryption with Thunderbird on Ubuntu 14.04. It assumes that you have the below mentioned prerequisites in place and you have an idea about how it works. If not, please consult the links at the ending of the article, under “Resources”. Continue reading “Sending encrypted emails using Thunderbird”
Even though I was using Linux for a while, I really didn’t got the idea with the file permissions clear from the beginning. Or even after a year. Changing permissions to allow certain things to happen (e.g. execute a script file) was embedded into my habits, but without really understanding what was happening. Nor did I was that interested to find out, but there is a point where you really want to know what you’re doing and not run commands just because you want “stuff working”.
During a cool project where I was using FOG (free open-source ghost) I realized that having a PXE boot server can pose numerous advantages. I wanted a PXE boot server that included FOG and it’s capabilities along with a multitude of operating systems and utilities that can be installed / ran over the network. This can replace the need of having a X number of CDs/DVDs/USB sticks around and the best of it all, multiple PCs can be booted with the same live OS or utility at the same time. Continue reading “All in one PXE server”
During a project, I ended up needing to make a PC that was on 2 subnets into a gateway. This, of course, led to a lot of packet tracing and questions on how to set this up properly. Continue reading “Turning a PC into a gateway”
A SSH tunnel is the SSH connection between a client and a SSH server, through which we direct our traffic. To better understand this, the diagram below illustrates it very simple. A client PC located in the US establishes a SSH connection wit SSH server located somewhere in Europe. The client PC is accessing google.com, through an SSH tunel (green line) and directly, with no SSH tunnel (blue line). When the user has accessed google.com through the SSH tunnel, google.com will process the visit as it have came from the SSH server in EU, thus resulting in google.com encountering a european IP. In the other case (blue line), the client PC is accessing google.com as normal, google.com processing its IP as originating from the US. Continue reading “What is SSH tunneling”
Ubuntus network manager cannot connect to Cisco Anyconnect VPN by default and you have to install an extra package. You can get pretty confused when looking for which package exactly. Continue reading “VPN to Cisco AnyConnect”
Puppet is an open-source automation software for IT. It can be used to control PC like you were controlling them by hand, but in an automated fashion. This is pretty useful in many scenarios, mostly for corporate environments where managing workstations and servers can be a real pain if it’s done manually, but it has its uses even in home scenarios or small businesses. Continue reading “Starting out with Puppet”