The ramblings of a computer geek
Although not good security practice, it can be helpful for a user to account to have at least some (or all) sudo ability without the need to re-enter the user’s password to gain sudoers. By adding the user within the file /etc/sudoers (via visudo is recommended for Ubuntu Linux), with the following, you can ensure … Read more
In part 4 of the series we are exploring Metrics. Although we’ll go into more detail later on in the series. Kubernetes can collect metrics of attributes like CPU or Memory etc. These metrics are collected by a Metrics Server, you can use the built in Kubernetes one (Metrics Server), or you can use external … Read more
We had an interesting issue where our EXIM configuration was flattening a subdomain’s “From” address, i.e. it was re-writing an email’s From (HFrom) and MailFrom (return-path/envelope-from) headers to @domain.com addresses, i.e. to catch emails such as root@mymachine.domain.comand re-write the From (HFrom) and MailFrom (return-path/envelope-from) to root@domain.com instead. Problem was, this configuration wasn’t documented, so needed a bit of investigation; but is also a good learning point … Read more
Firstly, a disclaimer. Although you can store values, specifically secrets (e.g. passwords) within Environment Variables so that you are not storing them in your Terraform template code there are better ways, for example by use of a formal Secrets Management solution. However, this article will show you how you can use Environment Variables to “safely” … Read more
Following on from a previous article https://geekmungus.co.uk/?p=4510 we now investigate some more into using Ansible for configuration management and installations. As something we can use as an example, we’re going to setup a simple Bind DNS server, which we can use to explore how to manage the installation of Bind and it’s configuration within Ansible. … Read more
Although there are other ways to do it, here is a quick way to tree list directories and files:
Sometimes you have some kit that is just old and isn’t supporting the recent (and secure) key algorithms. If you connect from a client without the correct set of ciphers available, so the client and the server can come to some agreement on a mutually supported cipher set, you’ll see an error such as: If … Read more
IPerf is a tool that can be used to measure the bandwidth and quality of a network link. Its a useful little tool, so I’ll introduce some of the basics of how you can use it to perform some tests. Bear in mind this is not an exhaustive guide, there are many tweaks that can … Read more
If you need to perform a Ping scan of a subnet, you can use the following command, its quick and dirty approach, although its not really that quick when it comes to actually running. The below will scan the subnet 192.168.1.0/24, from 192.168.1.1 to 192.168.1.254. If you want to speed things up a bit, you … Read more
Allow a connection from a particular remote IP address to any IP address on the local machine on a specific port (TCP & UDP). Verify with: