The Author – Bart Busschots
Creative Commons
Unless otherwise stated, the content on this site is licensed under Creative Commons Attribution, Noncommercial, No Derivative Works 3.0 License
Jul
26
TTT Part 39 of n – Advanced TMUX
Filed Under System Administration, Computers & Tech on July 26, 2020 | Leave a Comment
In the previous instalment we learned how to use the tmux as a replacement for the screen command which has been deprecated on RedHat Enterprise Linux (and hence CentOS too). In this instalment we’ll take TMUX to the next level, making use of the fact that a single TMUX session can contain arbitrarily many windows, each consisting of arbitrarily many panes.
As a reminder from last time — in the TMUX-universe, sessions contain windows contain panes. By default a session contains one window which contains one full-width and full-height pane. Windows can be thought of as stacking behind each other, like tabs in a browser, and panes are arrayed next to each other within a window.
Jul
11
TTT Part 38 of n – TMUX (A Screen Alternative)
Filed Under Computers & Tech on July 11, 2020 | Leave a Comment
Since we covered the screen command in instalment 36, it has been deprecated in Red Enterprise Linux 8, and the official advice from Red Hat is to transition to the tmux command. Having been a fan of screen for years, I was skeptical, but I shouldn’t have been — tmux can do everything screen can, it can arguably do it better, and, it can do much more than screen ever could!
May
25
TTT Part 37 of n – SSH Agents
Filed Under System Administration, Computers & Tech on May 25, 2017 | 2 Comments
Since we covered SSH in parts 29 & 30, Apple have changed how their desktop OS deals with the passphrases protecting SSH identities (key pairs). This provides us a good opportunity to have a look at the SSH Agent in general, and, how things have changed on the Mac in particular.
The good news is that while things have changed on the Mac, with a small amount of effort, you can get back all the convenience and security you had before.
Nov
19
TTT Part 36 of n – screen & cron
Filed Under System Administration, Computers & Tech on November 19, 2016 | 4 Comments
The previous 13 instalments in this series related to networking, but we’re going to change tack completely for this instalment, and look at two un-reltaed, but very useful terminal commands – screen, and cron.
screen is a utility that allows for the creation of persistent virtual terminal sessions that you can disconnect from without terminating, and reconnect and pick up where you left off at a later time. screen is particularly useful when used in conjunction with SSH.
cron on the other hand is a system for automatically executing recurring tasks. It’s extremely flexible, and very useful for things like scheduling backups to run in the middle of the night.
Jul
5
TTT Part 35 of n – HTTP Commands
Filed Under System Administration, Computers & Tech on July 5, 2015 | 6 Comments
The previous instalment we introduced the HTTP protocol. In this instalment we’ll look at three terminal commands which make use of the HTTP protocol.
We’ll start by browsing from the terminal, and then move on to a pair of very similar commands for making HTTP requests from the terminal. These two commands can do many things, but we’ll focus on two specific use-cases, downloading files, and viewing HTTP headers.
May
9
TTT Part 34 of n – Introducing HTTP
Filed Under System Administration, Software Development, Computers & Tech on May 9, 2015 | 2 Comments
In the previous instalment we finished a five-part series on SSH. Before moving on, lets take a moment to step back and look at the big-picture. The five SSH instalments are all part of the now long-running series on networking. We have been working our way through the networking stack since instalment 23. We started at the bottom of the stack, and have worked our way up. We are not exploring protocols in the Application Layer.
In this instalment we’re moving on from SSH to HTTP, the protocol that powers the world wide web.
Before we look at some HTTP-related terminal commands, we need a basic understanding of how HTTP works, so that’s what this instalment is all about.
Apr
25
TTT Part 33 of n – SSH ‘Bookmarks’
Filed Under System Administration, Security, Computers & Tech on April 25, 2015 | 3 Comments
This is the final SSH instalment. So far we’ve learned how to securely execute terminal commands on remote computers, how to securely copy files across the network using SSH, how to add both security and convenience to both those operations with SSH key pairs, and how to tunnel just about anything through SSH. In this final instalment we’ll look two approaches for creating SSH bookmarks, SSH config files, and SSH GUIs.
Apr
6
TTT Part 32 of n – SSH Tunnelling
Filed Under Computers & Tech, System Administration, Security on April 6, 2015 | 3 Comments
This is the fourth SSH instalment. So far we’ve learned how to securely execute terminal commands on remote computers, how to securely copy files across the network using SSH, and how to add both security and convenience to both those operations with SSH key pairs.
As we saw in the previous instalment, SSH’s ability to provide a secure connection between two computers can be used in many different ways. In this instalment we’ll learn about three more ways to encapsulate other network traffic within an SSH connection, adding encryption to that traffic.
Running commands and copying files are the kinds of things most people do, so the three SSH instalments to date have been quite generally applicable. That is not the case for this instalment. The three SSH features we’ll be discussing are all very useful to those who need them, but only a minority will have a use for any one of these features. However, even if you don’t need these features today, I would argue that it’s good to know these features exist, because they could well solve a problem you’ll have in the future.
There will be illustrations of the uses for these technologies, but not commands you type into your terminal to play along at home. That makes this an unusual instalment, but I hope you will still find it worthwhile.
Apr
4
TTT Part 31 of n – SSH File Transfers
Filed Under System Administration, Computers & Tech on April 4, 2015 | 5 Comments
In Part 29 of n we learned how to use SSH to execute commands on a remote computer. In the previous instalment we learned how to add security and convenience to SSH connections using SSH key-pairs.
The most important thing SSH provides is an encrypted connection between two computers. As we’ve seen, that encrypted connection can be used to securely issue terminal commands to a remote computer, but that same secured channel can also be used to secure other network connections between computers. In this instalment we’ll look at three different ways of securely copying files between computers through an SSH connection, and in the next instalment we’ll look at tunnelling just about any network connection through an SSH connection.
Mar
29
TTT Part 30 of n – SSHing More Securely
Filed Under System Administration, Security, Computers & Tech on March 29, 2015 | 7 Comments
In the previous instalment we saw how we can use SSH to execute a single command on a remote computer, or, to get a command shell on a remote computer. We also saw how SSH uses host keys to protect us from man-in-the-middle (MITM) attacks.
In this instalment we’re going to look at how we can improve both SSH security and convenience with SSH keys.