While Varnish is most famous for its speedy caching capabilities, it is also a general Swiss army knife of web serving. In the spirit of Christmas, here’s Twelve Days of Varnish Cache, or at least, twelve use cases.
And no, none of these examples are proof-read nor tested. They are only left as a taste of what Varnish can do. Quality assurance is left as an exercise to the happy reader.
So, the database is slow - why?
There can be several reasons for this. Perhaps a few very heavy queries are bogging down the database. In this case, you’d typically set up slow query logging and find them in the slow.log. However, sometimes the reason is simply lots of frequent queries.
The simple query is run twice a second and completed in 30ms during the beta testing. However, the database has grown and the query contains clauses not catched by ... [continue reading]
In today’s threat landscape, with botnets, ransomware, and unpatched and unprotected IoT toasters and garbage bins in every home, the ability to quickly and easily identify suspicious activities and artifacts is probably more important than ever before. If your company’s web server is being probed from a particularly malicious IP network, you might want some alarms to go off; if a zip file known to contain a variant of a cryptovirus crosses your network perimeters, someone should be told; and ... [continue reading]
Log-rotation is a key for running a stable server, but removing log files is often an anathema to security, traceability, and server history. In reality, you want a perfect rotation setup in order to maximise the retention of logs.
Instead of trying to continuously trying to balance the number of logs to keep on disk, why not just set the “rotate” value to a higher value and add a small script in cron to handle deletion of old files?
When installing OpenShift, the default certificates that are being installed are self-certified. Although this gives you functional encryption, this is in no way best practice and is especially annoying for the route being exposed for the Hawkular metrics, which is integrated within the Web console.
Luckily there is a relatively easy (and did I mention it is free?) solution: use Let’s Encrypt as your certificate authority.
Let’s Encrypt is an automated and open certificate ... [continue reading]
The other day, as I just had updated my workstation to Fedora 27, I realized maybe the Include statement in ssh_config(5) had been implemented. And indeed it had.
So it’s time to reorganize my ssh-config-generate script, FoxyProxy browser plugin for tunneling web traffic through SSH, and maybe even setting up systemd so I don’t have to manually initiate the SSH sessions!
Now why would I need this? Consider the following problem: I need to connect to the web interface of ... [continue reading]
Provisioning of new servers can be a daunting experience. Back in days it meant booting the machine with a CD or a DVD and doing manual choices. Automation of the installation process makes the process faster and less prone to human errors.
Network installation helps the process, but you still need to know the hardware to be able to automate provisioning.
When dealing with Virtual Machines, you decide the parameters for the hardware so the machines can be defined by ... [continue reading]
In parallel with an SSH/telnet honeypot, I’m also running an SMTP honeypot using INetSim. The SMTP honeypot is only one of many functions of INetSim; this article will cover the SMTP component only.
The SMTP part of INetSim has been configured with the following settings in inetsim.conf:
start_service smtp smtp_bind_port 25 smtp_fqdn_hostname darkstar.example.org smtp_banner "SMTP Mailer ready." smtp_helo_required yes smtp_extended_smtp ... [continue reading]
I want backup sysadmins to have login access to some systems, with said access rarely (if ever) used. To prevent abuse I’d like strong audit logging, logging that stands out from the rest of all the logging, logging that cannot be tampered with, and that can easily be followed up in case of abuse. I’ve been fixing a working setup through PAM, sending emails or instant messaging through third-parties. Jump down to the last section (“Specific complete examples”) to find ... [continue reading]
OpenShift is currently en vogue in the company. The ease of use and scalability found in a container based system allows us to automate the build and deployment steps of containers through software like Kubernetes/OpenShift.
We have visited Jekyll in several previous blog posts. Our techblog and the SysAdvent calendar (decomissioned as per 2023) utilize the Jekyll software to produce a static site from markdown content. The content and templates is stored in Git repositories on an ... [continue reading]