tag: linux

Simple server alerts on a need-to-know basis

18 Dec, 2021 - 10 minutes
Log aggregation systems are fantastic. As are time-series metrics databases. But that’s not what this post is about. These methods aren’t a replacement for those systems at all, but a basic way to implement the core basics of monitoring and alerting. You see, the strength of a SIEM or log aggregation system is its numbers. It correlates data from hundreds or thousands of sources, giving very important insights about overall system usage patterns, login activity, audit trails, and more.

NUC crashes on debian 11 - How I fixed it

13 Dec, 2021 - 3 minutes
I recently installed Debian Bullseye on an old Intel NUCCAY6H mini PC I had lying around. It’s a great little device for a home server, as it’s very cheap, fits 16G of memory, and with 4 mini-cores it’s no slouch. The first install attempt didn’t go well, with missing firmware for the NIC causing hanging for a couple minutes during boot. This happens quite a bit with Debian’s hard-line stance on binary blobs, so I re-installed with the non-free install media.

4 easy steps to make your server less dangerously insecure

8 Nov, 2021 - 5 minutes
There are lots of “very correct” ways to make your server “very secure.” Most of them rely on paid services, complicated agent-manager topologies, and cool buzzwords like “zero trust”. However, as they say, perfection is the enemy of progress. Many are discouraged by this absolutist approach to server safety, and forget the very basics. Obviously, the expensive and complex solutions exist for a reason, but at the same time a little goes a long way.

Domesticated Kubernetes Networking

30 Apr, 2021 - 6 minutes
I have wanted to run Kubernetes at home for some time, but the main obstacle has been a reliable solution for providing load balancing for ingress or services, and the lack of a reasonable way to manage NAT transparently. While publicly routable IPv4 addresses are seemingly limitless* in the cloud, typically we only get one at home. Similarly, there isn’t a straightforward way to build cloud-ey load balancers at home. While Google and Amazon can conjure up magic TCP load balancers on their complex overlay network platform, we don’t really have that luxury outside of the cloud.

Monitoring WAN speed with speedtest-cli and ElasticSearch

9 Dec, 2020 - 3 minutes
Similar to another post about WAN latency, this is a simple system to automate periodic internet speed tests. The two main components are speedtest-cli and ElasticSearch. These were chosen because I already had both set up and running, along with all the visualization and analytical software. To get a basic POC set up, just install ElasticSearch and Kibana with Docker. Once the node/cluster is running, the ‘speedtest client’ server can be set up.

Monitoring WAN latency with InfluxDB

7 Dec, 2020 - 2 minutes
This is a simple, ‘quick and dirty’ way to measure network latency over long periods of time. The only ‘complicated’ part is setting up InfluxDB, but I imagine that many folks already have it set up. To get started, check the official documentation. Network latency will be measured with the good old ping command, then formatted with generic Unix tools. Then, statistics are stored using the influxdb write endpoint using the line protocol format.

Installing Gentoo on a vintage Thinkpad T60

12 Nov, 2020 - 3 minutes
I installed Gentoo Linux on my vintage Thinkpad. This particular device has a rather colourful history. In mid 2015 I recovered it from an e-waste pile at my workplace and brought it back to life. In the years since, it’s been a playground of sorts. In five years it’s had four editions of Windows, three versions of BSD, exotic operating systems like Redox and ReactOS, and of course dozens of different Linux distributions.

ElasticSearch broke all my nice things (a story of cascading failure)

2 Sep, 2020 - 5 minutes
About two weeks ago, I upgraded my single node ElasticSearch cluster from 6.8.6 to the latest 7.9 version. Last night, all hell broke loose… The upgrade itself wasn’t perfect. There were some issues with my setup that the helpful “Upgrade Assistant” didn’t pick up before I had already committed. I was missing a few formerly optional parameters in my elasticsearch.yml config file, there were some odd field mappings that weren’t supported any more, and some date format issues with my grok scripts.

Malware on the Wire: Monitoring Network Traffic with Suricata and ClamAV

19 Jun, 2020 - 6 minutes
In my endless quest to essentially create a Cisco Firepower firewall for poor people, I found a bit of a gap in the open source security ecosystem. While we have great tools for detecting malicious network traffic patterns, we don’t have easy ways of detecting malicious files in transit. So, a bit of fiddling around later, and I have a fairly basic system for integrating Suricata’s ‘filestore’ functionality with ClamAV’s real time scanning, thereby producing a log containing the source and destination addresses of any malicious files detected.

Cloud Threat Protection with OSSEC and Suricata

19 May, 2020 - 11 minutes
The idea of this setup is to protect the Small Systems as well as we protect the Big Systems. This solution uses a proven stack to protect webservers from modern threats. Using OSSEC, Suricata, and the built-in firewall capabilities of a modern Linux system it is possible to build a low maintenance and stable threat protection platform with relatively low performance impacts. It’s been specifically designed to be simple. The idea is that it will keep you on a ‘need to know basis’ and otherwise stay quiet and do it’s job.

Surviving the Apocalypse with an Offline Wikipedia Server

26 Mar, 2020 - 5 minutes
For many years we’ve taken for granted the ability to settle any argument with Wikipedia. For so long, we’ve been able to settle any trivial dispute with a simple text search. That could change. I’m not really trying to fear-monger, but it’s always possible that the internet might go out and stay out. And like hell I’m going to sit in quarantine with my partner and not be able to settle up with Wikipedia!

Being Attacked by Bots

18 Feb, 2020 - 6 minutes
On the 19th of January 2020, a malicious actor launched an attack against my home infrastructure. At 42 minutes after midnight a device located in Buenos Aires, Argentina began attacking my proxy server. For the next six minutes, approximately 150 malicious HTTP requests were made. Fortunately, every single one of these requests was met with a HTTP/400 response, that’s because I don’t use Apache Struts 2 which this bot was attempting to exploit.

Linux Router, Firewall and IDS Appliance

14 Feb, 2020 - 10 minutes
Over the years, I’ve chewed through quite a few different routers, firewalls, even virtual appliances to connect my home network to the internet. Though most of these provided positive experiences, all of them had at least one point of friction, sometimes to the point of being a dealbreaker. PFSense is a great platform, but has terrible ethics. Sophos is proprietary and has an awful CLI. Untangle feels more like an ad than a product.

Fix an Oversharded Elasticsearch Cluster

25 Oct, 2019 - 8 minutes
TL;DR The default settings for Logstash index rotation are bad and will break your cluster after a few months unless you change the rotation strategy. If you’re anything like me, you probably read somebody’s cool blog about how awesome ELK stack is and just had to have a piece of it. So you went through the quick start guide, googled your way through getting it up and running, then BAM you had an awesome logging system with all the bells and whistles!

Automating KVM Virtualization

28 Sep, 2019 - 4 minutes
Think of it like, “OpenStack for cheapskates." There are plenty of ways to automate the provisioning of virtual machines, and while this isn’t the best way it certainly works great for me. I am fortunate enough to have a very heterogeneous environment at home; aside from a few appliances nearly all my virtual machines are running Ubuntu 18.04. This approach certainly won’t work for those who have a mixed environment with different versions Linux, Windows, and BSD derivatives.

Update all your linux servers as fast as possible

7 Sep, 2019 - 2 minutes
Do you ever just update everything? There’s a few times you might need to do this. For example, some nasty vulnerability comes along and ruins your week. Or maybe you just want to be super up to date because you have a strange compulsion to have the latest and greatest of everything. Ether way, here’s my solution: Use Ansible inventories to update all your servers I wrote this playbook as a simple way to ‘freshen up’ my homelab after months of neglect.

Cleanup Systemd Journald Storage

9 Jul, 2019 - 2 minutes
With the move from sysvinit to systemd, there were lots of small but important changes to the Linux ecosystem. One of them was the move from traditional syslog daemons to Systemd Journald. Now I’m not going to say this is a good or bad thing, as it entirely depends on your old habits and new optimism. What it does mean is a move to a faster and more flexible system log format but at the cost of some added complexity.

Clustering KVM with Ceph Storage

4 Mar, 2019 - 12 minutes
I have, for a long time, been fascinated and terrified by “Virtual SAN” solutions. The idea of combining storage and compute seems on the surface very attractive. It allows us to scale out our storage and compute together or separately in relatively small and affordable units, helping avoid the sticker shock of the upfront cost of storage systems. And as somebody especially prone to capex-phobia, that really is a great solution.

FreeRadius Active Directory Integration

17 Dec, 2018 - 7 minutes
I don’t like Microsoft NPS. That’s not to say that it’s a very convenient server role, which it absolutely is, or that it doesn’t have a place, which it sort of does. It’s just that it’s almost always, in my own opinion, a better idea to go with another option. So what’s wrong with using NPS? Requires a full windows license. Personally, I have an aversion to throwing away money, even if it’s somebody else’s money.

Deploy MDT Litetouch on Linux with TFTPD and Syslinux

4 Oct, 2018 - 5 minutes
No, I would not like to say hello, Cortana. Nothing is as monotonous, boring, and brain-numbingly automatable as installing Windows, installing applications, joining a domain, and clicking all the right boxes in all the right places. And it’s even worse in the latest versions of Windows 10, where we’re greeted by the condescending robot voice of Halo’s deceptive antagonist artificial intelligence during the OOBE setup phase. I’ve taken a particular liking to MDT, Microsoft’s solution to the absolute eye-glazing snorefest of configuring a new workstation or server.

Generating MSI transform files with Orca

1 Oct, 2018 - 5 minutes
Deploying MSI installers with group policy is super neat and super handy…. Most of the time. Sometimes, though, you need a bit more than just the default options when pushing out packages, and for those of us that don’t have a wheelbarrow full of money to burn on System Center there are two ways to do this: Use a GP Preference Item to distribute a configuration file to managed systems Create a transform set to apply to the MSI installer file While the first approach at first seems more straightforward, it does lead to the inevitable “GPO Spaghetti” once packages are added and removed.

Homebrew SAN

17 Sep, 2018 - 3 minutes
Everybody and their aunt has a NAS at home, but what about something with a bit more pizzazz? How about if I build a system out of standard, off the shelf, ‘surplus sale’ gear and spin it into a really neat storage appliance? The Gear At Fanshawe College, the ‘Asset Sale’ is a proud tradition. IT students line up around the block to get good deals on retired and scratch-and-dent electronics.