Feb 122024
 

So two days ago, I upgraded my main workstation to Ubuntu 23.10; a few little issues (mostly related to my own scripts), but nothing serious. Yet.

On the following day, my smart TV box started misbehaving. It couldn’t see any of the videos NFS mounted from my workstation, ITVX threw up a website error (this should have been a clue), but Youtube worked fine (which showed that the network was working fine).

So I did the obvious thing and started checking the NFS parameters to see if anything had changed. Nothing definite but on the way I noticed that the TV box wasn’t getting an IPv4 address from the dhcp server; IPv6 was working fine but some services don’t work on an IPv6 network.

I foolishly assumed that the TV box had stopped requesting addresses via dhcp – backed by the dhcp logs which showed no requests had been logged since the previous day. Set a static address, and everything sprang into life (except for ITVX who seem to have decided that only approved TV boxes should be allowed to run their code).

Later that same day, I upgraded a switch which failed to come back (“Failed to adopt”) which caused a daisy-chained wireless access point to disappear (“Failed to adopt”). And then a little while later, a second unconnected wireless access point also disappeared.

After a few reboots of the switch (and access points), I finally checked the dhcp server and found that its root filesystem had become ‘read-only’. But that wasn’t the end of the misdiagnosis …

I assumed that the SD card in my dhcp server (a tiny ARM box) was fried, so made arrangements to backup the contents, buy a couple of replacements, and try a spare (which was broken). After the spare turned out to be broken, I ran fsck on the root filesystem of the original and a whole bunch of errors were fixed.

Re-installed into the ARM box, and everything sprang to life again.

I guess the moral of the story is that you should check the basic services before diving into making assumptions.

Upended Cannon
Jan 142024
 

Just seen a video title about how Linux defeated UNIX™; it is quite hard to dispute this givennd that that Linux is alive, well, and thriving. But I would argue that it isn’t quite true.

First of all, UNIX™ is technically alive as Solaris, HP-UX and AIX are still active. And there may well be rarer versions out there – and I’m excluding operating systems that meet the trademark requirements but aren’t really “Unix” (we could argue all day about what is and what isn’t “Unix”).

But the market for UNIX™ machines is a great deal smaller than it used to be. And why is that? I would argue that whilst Linux made the transition easier, it isn’t the real reason why many organisations swapped out their high-priced machines for cheaper machines.

And that gives a bit of a clue. Whilst the high-priced machines from Sun, SGI, HP, IBM, Digital, etc. weren’t over-priced they were expensive. The hardware was built to be exceptionally reliable – for example some of the Suns I worked with could deal with a processor failure by simply turning off that processor and letting an engineer replace the board all whilst the system was up and running.

No what “killed” those expensive UNIX™ machines was virtualisation and the use of commodity hardware. If a modern server dies, the virtual servers running on it are simply migrated to a working server suffering at worst a reboot (but probably not).

Plus there was a realisation that not everything needed to be continually available.

Through The Gateway
Dec 042023
 

Just for fun (I have admittedly a very weird sense of fun), I thought I’d have a look at one of the phishing emails that came into me. I’ll go through this bit by bit, picking out bits that first occurred to me …

Subject: LastPass : Required action needed regarding your account

Eh? Do I even have a LastPass account? I keep my passwords stored somewhere else, but it’s not impossible – I’ve been known to sign up to things just to test them out. Including cloud-based password managers.

But all the same, let’s give it a point on the suspicion scale. Running total: 1.

From: LastPass <yoji-okugawa1975@tg8.so-net.ne.jp>

Well LastPass certainly use a funny looking email domain (the bit to the right of the “@”), but Marketing departments sometimes aren’t aware of how important that email domain really is. On the other hand, “tg8.so-net.net.jp” does look particularly uncorporate, so let us give it a suspicion point.

Running total: 2

On the other hand, it is too easy to fake domains – I could very easily send you an email from the-management@lástpáss.com (and even more subtle equivalents of “a” – “а”, “ạ”, “ą”, “ä”, “à”, “á”, “ą”). And just to demonstrate something that looks identical can actually be quite different :-

In [8]: print(ord('а'))
1072

In [9]: print(ord('a'))
97

Now this isn’t to suggest that you should run your email headers through some Python code, but just that because something looks like lastpass.com doesn’t mean it really is. The next thing that jumped out at me was the body of the email – I may be well trained, but something new and shiny is still distracting :-

Now the first thing that jumps out at me is that red “Confirm my information” box. Screams “click here” doesn’t it? Well don’t click on it! In my email client (something you’re quite likely not using – claws-mail), if I hold the mouse pointed above a link, it’ll tell me where that link goes in the status bar of the client. In this case it shows up as https://tg8.benchurl.com/…. doesn’t look very much like lastpass.com does it? That’s sufficiently suspicious that I’ll award it 3 suspicion points.

Running total: 5

Notice how they don’t add a “Dear ${name}” to the top of the email? Not personally addressing email is ever so convenient to scammers that want to get your details – because they don’t necessarily know your name. That’s a suspicion point all on its own.

Running total: 6

Next note how it tries to rush you … “log in before January 16, 2024”. It’s subtler than many phishing scams, but it’s still trying to rush you. Add another suspicion point.

Running total: 7

There’s further details we could dig into, but that’s more than enough that the Delete button is the only thing this email should attract. That running total? It was just for fun, it’s not intended as a guideline for when to count something as a phishing email.

In the case of doubt, contact the company via other means.

Oct 132023
 

Do you have a disk in your computer to keep data on? Really? It must be quite old then. Most of us are switching to solid-state devices.

And even if your hard disk really is spinning rust, it technically isn’t one disk; it’s a number of them (individually called platters).

IBM terms all appropriate storage devices DASDs (direct-access storage device) which because it refers to what the storage device does rather than describes how it is constructed. Except for the difficulty pronouncing it, it makes a far better name.

How about cheating and referring to them as DASes?

Wooden and Concrete Seating
Jul 302023
 

Ah yes! Well the first thing to answer is what a terminal is.

A terminal is a device for communicating with text (graphics was possible but relatively rare especially in the early days) with a computer – you would type in a command in text and the computer would respond in text :-

» ls
1  2  bad-directory

Although the “terminal” is still available today in the form of a gooey program, the early terminals communicated with the computer with some form of serial port (usually RS232). The first terminals were modified teleprinters (often called “Teletypes” due to the domination of that company in the USA). These were large electromechanical devices where the display was paper – they were printing terminals.

The first terminals that displayed on a screen were very much like the printing terminals – they would “print” output from the computer on the last line of the screen and scroll for additional lines. Just like on a printing terminal except that once things scrolled off the top of the screen they were lost.

At this point in computing history, we’re just at the start of the microcomputer age; in fact one of the uses for which Intel’s second processor (the 8008) was developed was to operate as the heart of a computer terminal.

As the microprocessor controlled terminal was essentially run by software, programmers started adding in new features that would do things like clear the screen, move the cursor around the screen so you could display text anywhere you wanted.

At this point one definition of “dumb terminal” can be found – a terminal that just emulated a printing terminal was a dumb terminal; ones with additional features weren’t so dumb.

As the 1970s progressed, terminals gained more and more features and eventually some became capable of downloading software from the computer they were connected to and running that software locally. Such as (optionally) the HP 2647. Or the Bell Labs blit terminal.

Such terminals could be termed “smart” and their predecessors “dumb”. And if you notice a similarity with the somewhat later “thin clients“, you wouldn’t be entirely wrong.

Alternatively, some terminals (such as the IBM “green screen” terminals) operated in block mode where the terminal would allow a certain amount of editing within the terminal and send the result back to the computer a screen at a time. These necessarily had to have a certain amount of “smarts” built in, so they were smarter than character at a time terminals (thus “dumb”).

"Dumb" Terminal
A “dumb” terminal

So to an extent there is no real agreement on what a “dumb terminal” really is. Pick one that you like!