[this post has been partially damaged during a server failure on Sunday 11th July 2004, and it has been possible to recover only a part of it]
Oh your god. What a dream! It’s been years since I’ve dreamt anything so ‘out there’. Perhaps a result of all the Hobgoblin I drank last night. Perhaps caused by exam stress. Perhaps we really are just a product of the things we take in from the world around us – my dream seems to twist and contort …
[this post has been partially damaged during a server failure on 11 July 2004; with the exception of the images, it was recovered on 13 October 2018]
Paul has been stuck with a problem of late – he’s now living in university accomodation, and he’s found that he can’t connect through the university firewall to his external mail server. I advised him that it’s possible to set up an ‘SSH Tunnel’ (through central.aber.ac.uk) to fix this problem, but he hasn’t met with much success (see his blog entry for more details). In any case, here’s my investigation (and solution) to the problem.
How To Use SSH Tunnelling To Allow Services To Pass Through A Firewall
In my example, I’m going to try the opposite to what Paul is trying to achieve. I’m going to try to allow my POP3 e-mail client to get access to the university e-mail server
(pophost.aber.ac.uk). As things stand, this server is on the other side of the university firewall, and is inaccessible from outside. The server central.aber.ac.uk, however, is
accessible from both sides of the firewall. So what I’ve got is this (yes, I know that this is a gross oversimplification):
As you can see, connecting from my home PC is futile:
C:\Documents and Settings\Dan>telnet pophost.aber.ac.uk 110
Connecting To pophost.aber.ac.uk...Could not open connection to the host, on por
t 110: Connect failed
But if I SSH-in to central.aber.ac.uk…
central:~ $ telnet pophost.aber.ac.uk 110
Trying 144.124.16.40...
Connected to pophost.aber.ac.uk.
Escape character is '^]'.
+OK mailsplit Oct 2000 ready
So, what I need to do is to tell my SSH client to connect to central.aber.ac.uk, and forward specific traffic through the firewall to the mail server. Here’s what I needed to know:
(a) A free TCP port number on my own computer from which I can virtually ‘pipe’ the connection. Most numbers over 1024 are fine. I chose ‘9110’.
(b) The name of the mail server – ‘pophost.aber.ac.uk’.
(c) The TCP port to which I wanted to connect – the standard port for a POP3 mail server is ‘110’.
(d) My user name on a server which: (1) I can connect to; (2) can connect to the server specified in (b). It happens to be ‘dlh9’.
(e) The name of the server specified in (d) (i.e. ‘central.aber.ac.uk’).
(f) My password on the server. Like I’m going to tell you that.
The syntax is:
ssh -L (a):(b):(c) (d)@(e)
I’m using the non-commercial version of SSH Secure Shell Client, so here’s what happens:
C:\Documents and Settings\Dan>"\Program Files\SSH Secure Shell\ssh2.exe" -L 9110
:pophost.aber.ac.uk:110 dlh9@central.aber.ac.uk
dlh9's password:
Authentication successful.
At this point, I’m ready to go. Look what happens when I connect to port 9110 on my own computer, now…
C:\Documents and Settings\Dan>telnet localhost 9110
+OK mailsplit Oct 2000 ready
I could simply point my e-mail program at the ‘mail server’ at localhost:9110, and I’d be able to collect my university e-mail (so long as my SSH connection remained open).
Hopefully this guide will help some folks out there who are struggling with this kind of thing, and in particular, help Paul.
[this post has been partially damaged during a server failure on Sunday 11th July 2004, and it has been possible to recover only a part of it]
[more of this post was recovered on 13 October 2018]
I’ve just written my very first Operating System! And I’m putting it here, online, so that you can give it a go if you like. And no, you don’t need to install it – just put it on a floppy disk and try it from there (no, you can’t boot it from a CD yet)!
Don’t expect too much. There’s no user interface (not even a command line). All it is is a bootloader and a kernel that ‘displays pretty squares’ (I stole the ‘pretty squares’ code from somebody else – my Assesmbly needs some work!).
Hardware Requirements
386SX/25MHz or faster processessor
520K or better memory
Floppy disk drive
Instructions For Use
1. Download the floppy disk image file [34K]
2. Download and install WinImage 6.1 (this program lets you write floppy disk image files to
floppy disks).
3. Open the image file in WinImage, insert a floppy disk, and select “Format And Write Floppy Disk” from the “Disk” menu. The Operating System will be written to the floppy disk.
4. To run it, you need to reboot your computer with the floppy disk in the drive. If this doesn’t …
I’ve spent the evening looking at bootloader source code (small programs, crucial to every Operating System, which do the first fundamental steps towards loading the kernel, the ‘core’ of the OS). Just to show you quite how scary this stuff is, here’s a snippet of code to “stop the floppy drive motor from spinning”:
mov dx,3F2h
mov al,0
out dx,al
Then you’re old enough to appreciate this: OSNews is running an article about the upcoming fight between Google and Microsoft. Where the Netscape/Microsoft battle involved web browsers, the weapons of the Google/Microsoft battle will be search engines and e-mail services.
If you’re confused as to how companies can be fighting by trying to increase the market share of their free product, read the article.
[this post has been partially damaged during a server failure on Sunday 11th July 2004, and it has been possible to recover only a part of it]
[further parts of this post were recovered on 13 October 2018]
Now here’s an interesting article [security.itworld.com]. It seems that the European Union is investing €11 million over four years into developing a secure communication system based on quantum cryptography.
For those of you not in the know, quantum cryptography (for passing crypto keys) works like this:
Quantum Cryptography For Dummies
Claire and I stayed up late and played multiplayer Civilization 3: Conquests together. When the Carthaginians picked on her, I stuck up for her and razed one of their cities. We’re hoping that by working together, we might be able to get a spaceship to Alpha Centauri before 1900.
We played until it started to get light. Then we went to bed and rolled around, laughing. Then we had sex as the sun rose.
A long multiplayer games session followed by a shag. Is there anything more romantic?
This is a repost promoting content originally published elsewhere. See more things Dan's reposted.
This repost was published in hindsight, on 11 March 2019.
Ruth wrote:
Today we have been…
…testing Dan. Earlier I sent in to ask how many times the big Panda said ‘nice’ in Panda Ko Panda (12, 5 times referring to bamboo). When we were getting food at the Chinese, Dan accused Bryn of having sent that in (he was logged on at the time), I might have got away with it but I burst out laughing.
Then just now, Bryn and I were wondering how many cups of coffee you could make using all the water in the pacific ocean. In case anyone wants to try it, the answer is 259 million cups, using 518 million tablespoons of ground coffee. That’s a lot of caffeine!
Bryn: “Can you imagine the size of the coffee filter?”
Yay! Take a look at this piccy (especially you, Paul).
Just extracted this from the just-released minutes of our last staff meeting. It’s from a section about what tasks are assigned to whom:
Dan:
How very right.
[this post has been partially damaged during a server failure on Sunday 11th July 2004, and it has been possible to recover only a part of it]
In this era of pro-Linux and pro-Windows hoo-hah, it’s good to see an article who’s writer really has his head screwed on: Common OS Myths Debunked is a wonderful piece; go read it.
Linux is not the answer!
Windows is not the answer either!
Don’t even get me started on MacOS…
Operating…
Typhoid in my left arm. Hepatitis A in my right arm, and a heap of Malaria tablets to boot. Decided that the best way to get this lot into my bloodstream as fast as possible was a quick sprint around Aberystwyth. Now I feel slightly dizzy and nauseous. Lovely.
On the up-side, I didn’t have to pay for any of this medication. Today was the last day that the surgery I attend isn’t charging for those which are considered ‘holiday medication’.
Feeling a little more woozy now. Think I’ll dance for a bit to make sure it’s worked it’s way into my system properly (better to make myself hideously sick for a day than ill for a week, I say), then take a rest.
Hooray for pathogens!
WTF??? If you go to Symantec’s Online Virus Scanner using most browsers, you’ll be told that you need to use Microsoft Internet Explorer to continue! Isn’t this just asking for trouble? It’s like saying, “Yes, we’ll check your house is secure. Now just unlock your door…”
Just plain weird.
Yes, the the rumours you’ve heard are true – The Flat has been rearranged. In a mighty effort (and with the help of Claire, Paul and Bryn), we’ve pretty much ‘mirrored’ the room widthways. This change provides several benefits:
[damaged post partially recovered on multiple occasions]