Category Archive: Tech Tips

HOWTO: Use DD-WRT To Bypass Filters – Part 1: The story

This is part 1 of 3 in a series. This series is actually for an English class assignment, but I decided to put it on my main blog instead of my second blog (http://antani02.blogspot.com/).

==DISCLAIMER==

Use these methods at your own risk. If your workplace has an Acceptable Use Policy that forbids employees from bypassing the filter, then think before making the decision to do so.


The first time I bypassed an internet filter, I used WEP key cracking. I used this because there were 2 wireless networks, a non-filtered network, and a filtered network. It took me a few months to get it working properly, and at the end of it I had a fully functional method of cracking a 28-digit WEP key in 3 minutes with my laptop. I am now in a place where that will not work, so I had to exploit something else in the system to bypass the internet filter.

In case you don’t know what I am talking about, an internet filter is a filter that blocks certain websites (games, etc.)
The internet filter only filters port 80, and all other outbound ports are open (Yes, this is a very large security hole!) I started out by using SSH port forwarding from the filtered area to my home PC, effectively bypassing the connection (see diagram below).



I used that for a while, but decided to use something else that wouldn’t cost $9.00 a month in electricity. I then installed DD-WRT on my Linksys WRT160N router, and used the ssh server on the router.

This worked well too, but when I tried to play Second Life from the filtered area, it didn’t work. I then researched alternatives, and found that DD-WRT also has a VPN server. I decided to use the VPN server instead to see if that worked. It worked great, and although I don’t play Second Life anymore, it still has the added advantage of being able to access computers and printers on my home network.

In my next post, I will explain how to use VPN to bypass the filter.

How To Fix a Fedora Live CD That Doesn’t Boot

This morning I was having problems with a Fedora Live CD that I burned. After reading a bit online, I figured out the solution. I was originally burning it with Brasero, the CD buring software included with Ubuntu. I then tried a program K3D, available from the Ubuntu repositories.

I used these settings for burning:

- DAO/SAO mode (Disc At Once/Surface At Once)

- 8.0x burning speed

- K3D burning software

And the disc worked perfectly! I now have an installation of Fedora on my computer. That was my solution, it may not work for everyone, but if you are having problems, try it anyway!

The Hard Drive Space Misrepresentation

This post is about how Hard Disk manufacturers cleverly mislead you about how much space is actually on their drive. Before I write about that, I will tell the story of how I discovered this. So, here it goes:

I recently installed a firewall called ZoneAlarm. When it was installing, the computer froze, and I had to do a hard restart. This caused an incomplete installation, which may be the cause of my computer resetting within about a minute of booting Windows. This problem is almost certainly caused by ZoneAlarm. After messing around in Linux, trying to find a solution, I gave up and decided to reinstall Windows.

This is when the problem arose of my hard drive space. I never had problems with hard drive space before, with my 500gb desktop hard drive and my 320 GB laptop hard drive. Those hard drives add up to 720gb of space. This is both a good and a bad thing, because my backup hard drive is only 500 GB. I make absolutely sure that everything I have on my computer is backed up, because I have lost things in the past to all sorts of things (Usually starting with me messing with the partitions or something).

Since my laptop and desktop are both more than 75% full, I don’t have enough space for backups. In case you are wondering why I am talking about backups, it is because in order to reinstall Windows, I need to back my stuff up. So, I decide to buy another hard drive just for backups.

I go to PC Cyber, and buy a $72.00 (Canadian dollars) 1 TB internal hard drive. When I get home, I hook it up and boot Ubuntu. I try to open it to start copying files, but I realize there is no partition table (obviously). So, I go to the partition manager, and see that the drive is not 1 TB, but instead it is 931.51 GB. I discovered that the company that markets the drive (Western Digital) is misleading their buyers.

What they are doing is perfectly legal, because it is 1 TB. It is not a terabyte (TB), but instead a Tebibyte (TiB). You see, a TB is equivalent to 1000 GB. A TiB is equivalent to 1024 GB.

Computers read disk space in Binary multiples of bits/bytes. Which means units such as TiB, GiB and so on. I won’t go into much more detail than that, but you can see how it can create a difference like that.

An odd fix for an odd problem – fixed!

It turned out that the problem I was experiencing (Documented in this post) was that the 24-pin power cable (the big one that supplies power to the motherboard) was loose. I at first couldn’t believe that I had honestly missed that. It was probably the first thing the people at the computer store checked, and they still charged me $35.00 for it.

Anyway, that fixed it for good.

An odd fix for an odd problem

As seen in my recent video tutorial, I replaced my computer’s wireless card. The old wireless card had a few problems, it rarely even connected, and when it did connect, it was very slow. This is to be expected from a driver that was updated in 2006, and a computer running Windows 7. But, that is beside the point.

After replacing that card, I had a very weird problem. I spent 4 hours trying to fix it, when the actual fix took only 5 minutes. The first time I turned on the computer after installing the new wireless card, it turned off as soon as it got to “starting Windows”. There was no blue screen or error, it just died. When I pressed the power button again, nothing happened. I unlplugged the machine and plugged it back in, and pressed Power. This time, it turned on for half a second (fans, etc.), and then died again.

Oddly, it would only do this once, unless you unplugged it and plugged it back in. If you didn’t do that, it the power button would do nothing until you unplugged it/plugged it back. After hours of googling and trying things, I tried booting without the graphics card, this time, the computer stayed on. I unplugged it and put the card back in, and it worked fine.

In my opinion, that is quite a weird fix, because the graphics card shouldn’t make a difference to whether or not it boots. If anyone has any ideas about this, please comment.

How to fix a “cannot print” or “cannot detect” error on a Brother MFC-495CW

I have been having some very frustrating problems recently with my almost brand-new (one month old) Brother MFC-495CW Wireless all-in-one color printer. One day, I choked the power bar because the computer was frozen, and when I turned the power bar back on, the printer went “BEEP BEEP BEEEEP”.

I got up and went to look at the printer, and what do I see? This stupid message:


Just. Great. I tried reinstalling the cartridge slowly, and I close the cartridge door, and what do I hear? “BEEP BEEP BEEP”. Oh, what now?. I look at the printer again, and it says “Cannot print” on the screen. Great, now the ink has magically disappeared. I try all sorts of things, unplugging the printer, trying to clean the cartridges, and even removing ALL the cartridges and putting them back in. The latter resulted in all the cartridges except for the magenta to become empty as well.

 A few days later, I am fed up and decide to call Brother Customer Service. After about 18 minutes of being on hold, I talk to some one. I tell them my issue, and they are about to tell me that they don’t know the answer, and I should take it to a technician, I suggest a ‘Hard Reset”. This lets me in on a small secret about this printer: The maintenance mode (I will explain how to get into maintenance mode at the end of the post). I do what the tell me to reset the printer, but to no avail. Then they tell me the inevitable, which is that I must take it to a “Qualified Brother technician”.

For the record, the phone representative  told me something that was inconsistent with what the Owner’s Manual said, which was that the printer uses a sensor to detect ink, instead of simply counting the amount of ink used since the cartridge was installed to determine the current ink level. If that was the case, a hard reset should almost certainly fix it.

The call ends, and I sit there wondering what else I can do. I decide to look at the one functioning cartridge: The Magenta (or ‘pinkish-red’) cartridge. I notice a small clear ‘window’ on the front of the cartridge. It has a small amount of pinkish-red ink in it. I look at the other cartridges, they all have the same window, but there is no ink.

Right now, it may seem that the printer is right, and there is no ink in there. But there is, and the cartridge is just designed so that the ink appears to the printer to ‘run out’ before it is actually empty. Now for the solution:


I decided to use some black electrical tape to cover up the cartridges’ small ‘window’, so the printer would see it as full. Here is an image of the window:



And here is the window with some electrical tape over it:



I did the same thing for all the other cartridges that weren’t working, and the problem is now fixed! As a side note, you may have noticed that in the first image, of the error on the screen only the black cartridge had an error. This is because I only had the idea of posting this tutorial on my blog AFTER fixing the other two cartridges. Anyway, here is the ink volume screen after this fix:


Now, the printer thinks that all the cartridges are full. Beware though, I have heard that is not good to run the printer on a cartridge that has only air inside it, as it may damage the print head. So after applying this fix, replace the ink cartridges when you notice the ink quality is beginning to degrade.


Now, the maintenance mode:


To get into maintenance mode with this printer, while the printer is on hold down the menu button. Now, unplug the printer, and DO NOT take your finger off the button. With your finger still on the button, plug the printer back in. When the printer displays “MAINTENANCE” on the screen, you may remove your finger. To use maintenance mode, enter one of these codes, and press BLACK START. To exit, type in 99.


01 Full RAM clear (see 91 below for retaining user programming)
02 scanner initialize (feed a white sheet, then a black sheet)
05 white level
09 print test
10 modify soft switches
11 print configuration list
16 panel test
19 CML test
20 signal test
21 tonal test
23 filter RX
54 scan edge
55 scanner area
66 test print memo
75 display drum life (if enabled on laser models)
76 reset drum life counter (laser models)
91 parameter initialize (user programming remains intact)
95 protection
99 Exit maintenance mode


Thank you for reading this tutorial, and please tell me if you don’t understand something I said.

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