I was trying to edit the sudoers file using visudo in new Ubuntu system. The default editor was set to nano as usual.
After making the changes, when I went to save the file using Ctrl+O, I noticed that it was writing it out to /etc/sudoers.tmp file instead of /etc/sudoers file.
The explanation of why it was this way was interesting. I had never really put any thought to this earlier.
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Tailscale is an open-source VPN. It works very well. However, its control server is still on their systems. Headscale is an open-source, self-hosted implementation of the Tailscale control server.
Here, I’ll list down the steps required to install Headscale on Ubuntu.
Continue readingAny process can be run as a non-root user service.
The first criteria to have a service as a non-root user is to have the service be kept running even when the user is not logged in.
However, having a web server places an additional challenge – port 80 and port 443 which are basically the http and the https ports need to be bound by a user with administrative privileges because they are lower ports.
To create a systemd service in Linux, we need to create the unit file under /etc/systemd/system/ as myapp.service.
This means that to stop, restart or debug this service we need root access.
I wanted to create a service which a user without root access would be able to start, stop, debug.
So, all of a sudden, one of our servers, while trying to connect to another, started giving this cryptic error –
OpenSSL::SSL::SSLError - SSL_connect returned=1 errno=0 unsafe legacy renegotiation disabled
These kind of errors are usually dependent on some system updates. But the error seemed to be coming from the target server. After a bit of searching around, this article gave the most understandable information.
From that article –
This “unsafe legacy renegotiation disabled” error happens when connecting to outdated endpoints that do not support RFC 5746 secure renegotiation. Ideally, the endpoints causing these errors should be upgraded for security reasons.
In the same article, they mention that it should be possible to remove this security check, but the solutions mentioned there didn’t work.
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I’ve become a big fan of fzf since I discovered it.
However, after a recent upgrade, when I pressed Ctrl+R, I got the following error –
unknown option: --scheme=history
After some searching, found the following solution.
Remove fzf from /usr/bin/ and relink it.
Run these two commands in order –
sudo rm /usr/bin/fzf sudo ln -s ~/.fzf/bin/fzf /usr/bin/fzf
fzf is a serious timesaver. To be able to quickly go through past commands and in a fuzzy manner, especially when you don’t recall the exact command is a Godsend!
To install fzf on Linux, we need to
a) clone the repository into the system
git clone --depth 1 https://github.com/junegunn/fzf.git ~/.fzf
b) run the command which will add the relevant shortcut keys
~/.fzf/install --all
There are a bunch of other stuff that can be done once fzf is installed. For example, to see instant file previews –
fzf --preview 'less {}'
And if there is bat also installed, then the previews can show syntax highlighting and line numbers also!
fzf --preview 'bat --color=always --style=numbers --line-range=:100 {}'
This was quite a head-scratcher. I wanted to remove a user sammy from the sudo group and did that by running this as root
root> deluser sammy sudo
However, when I logged in as sammy I was still able to run –
sammy> sudo su
Checking which groups the user belonged to was of no help either.
sammy> groups sammyContinue reading
I’ve long been a user of DBeaver which works so well across different OSes, so recently I wanted to set up the cloud version called cloudbeaver.
In the course of doing that, I had to generate SSH keys to be able to access remote databases via SSH.
The standard way of generating SSH keys is to run this command.
> ssh-keygen -t rsa
This by default creates id_rsa and id_rsa.pub under <home directory>/.ssh folder (both in Windows and Linux)
Every time I need to check the current version of Ubuntu, I have to run
$> lsb_release -a
But what if lsb_release is not installed?
The easiest way is to run
$> cat /etc/*release
This gives me an output like this!
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