Feb

14

TTT Part 29 of n – Intro to SSH

Filed Under System Administration, Security, Computers & Tech on February 14, 2015 | 8 Comments

This post is part 29 of 39 in the series Taming the Terminal

In the previous six instalments we looked in detail at how TCP/IP networks tick. In these instalments we worked our way up from the bottom of the four-layer TCP/IP network model to the top, finishing off with a look at two protocols in the Application Layer at the top of the stack. Those two protocols, DHCP & DNS exist in the top layer, but are different to most other top layer protools in that they can reasonably be described as forming part of the infrastructure of the internet. The email and web protocols may site within the same network layer, but they still rely on DNS to function.

For the remainder of the networking section in this series we’ve moving away from infrastructure-like protocols, and focusing on the user-facing Application Layer protocols. The first of these we’ll be looking at is the Secure Shell, or SSH. This protocol is one of the absolute work-horses of the internet, and a vital tool for all Linux, Unix, and OS X sysadmins.

At it’s simplest level SSH allows you to execute commands on a remote computer, but because it was designed around the concept of a secure tunnel between two systems, SSH has expanded to allow all kinds of advanced features. The least-generous description of this could be that SSH has become a kind of sysadmins fridgeoven. But I don’t buy that, I prefer the alternative interpretation – it simply makes sense not to re-invent the wheel, and to allow as much information as possible to flow throw the secure connection SSH provides between the two end-points.

Today we’re just going to start with the basics, but in future instalments we’ll move on to the more advanced features.

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Feb

8

SubnetCalc.it re-skinned

Filed Under Computers & Tech, My Projects on February 8, 2015 | Leave a Comment

I’ve just completely re-skinned my IP subnet calculator over at www.subnetcalc.it, hopefully making it much easier on the eye. The original skin was basically the same as the one I used for XKPasswd which is fixed-width and hence very old fashioned. The biggest problem with a fixed-width design is that it doesn’t work well on either large or small screens, which is almost everyone these days!

The new skin is variable-width, so it should scale much better for people. Assuming people like this basic style, my plan is to migrate www.XKPasswd.net to this same basic design. In effect I’m using this new site to beta-test some ideas for XKPasswd.

I’d love to hear any constructive feedback people have.

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