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Pages with category Web Server

  • Introduction

    Often, when you build a website, you want columns.

    Common designs include

  • I just switched my websites from one server to another and noticed that on my main company site (http://www.m2osw.com) I would get a # at the end of the URL. Automatically added somehow. Thinking that could be a bad guy I checked the code and could not really see anything.

    Hitting "Back" once, I noticed that the # would be transformed to #atssh-digg. I don't have anything specific about digg on that page except the AddThis button. That adds Digg among some 150 different systems where you can share my pages.

  • Managing your own Drupal Download Site

    The other day, I was thinking, it would be nice if I could find the way to manage my own download site so people who use my modules that I do not provide directly on https://www.drupal.org would still show as expected (i.e. Green in the update window).

    I found this page about it: https://www.drupal.org/node/210984

    This is done by creating a service in your Drupal environment. You should use the ready made script named:

    project-release-serve-history.php

    which you can find in the D6 version of the Drupal project named Project. Being very ...

  • If you are running a webserver, you should use a webserver firewall. This prevents many attacks from being perpetrated on to your servers without the need to make your own applications more complex than necessary.

    The idea is very simple, if you have a few people who can edit your data from the Internet and those have a static IP address, you can check that the editor pages are only accessible to those IP addresses. Any other access can simply be blocked.

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  • I have been wondering, for a while, why is it that I get errors about DEFLATE no being known.

      [Sun Apr 11 22:41:23 2010] [error] an unknown filter was not added: DEFLATE
      [Sun Apr 11 22:48:54 2010] [error] an unknown filter was not added: DEFLATE
      [Sun Apr 11 22:50:23 2010] [error] an unknown filter was not added: DEFLATE
    

    I should have thought of it, the deflate module was not installed. That was it, but oh well... 8-)

    To tweak your Apache setup, use the following two lines:

      sudo a2enmod deflate
      sudo /etc/init.d/apache2 force-reload
    

    And you'll get rid of those ...

  • Error about a local certificate?!

    The other day, I got a new certificate from godaddy.com. I installed the certificate by replacing the files and simply restarting Apache. I then checked in Sea Monkey and it worked great. Checking the certificate it told me "valid for another 3 years."

    A few days later I got an error from eFax saying that our certificate could not be verified. Weird... I tried with wget and got the error! Hmmm... I tried again with SeaMonkey, just fine. Then I tried with FireFox, error too! The error with wget is like this:

    ERROR: Certificate verification ...
  • Today we again ran in an out of memory error. As we are adding more websites our foot print is growing... Our servers use a VPS that has limited resources and whenever the limit is reached, the system automatically kills processes. How the VPS selects the process to kill isn't clear to me, but twice it has been our database manager meaning that all of a sudden all the websites stop working.

    So... We got an extra bit of RAM because our package allowed it, but that's still small.

  • Today I got an error about an .htaccess file that Apache2 could not load.

       pcfg_openfile: unable to check htaccess file, ensure it is readable
    

    I looked like 10 times in that folder to make sure the .htaccess was fine, which meant looking that there wasn't an actual .htaccess file there!

    The fact is not exactly that the file cannot be opened, it has more to do with the parent folder accessibility. Somehow Apache2 does not check the parent folder accessibility and prints the error since, indeed, it gets an error other than the usual "File Not Found". (It's getting the ...

  • I've been using Drupal for a while and only now started to notice a problem with the cache of JavaScript code. In general, I don't cache the JS since they are not dynamic files. But we do that with Snap!.

    The Apache mime module offers two options: AddType and AddEncoding

    Both options are used in a similar way meaning that both react on file extensions. When a match is found, the corresponding MIME type or content encoding is attached to the content being sent.

    If you install the MIME module, it will attempt encode data properly for the most general case, but not all cases. That is, it does

  • I've been looking around every now and then to try to understand how I could create a server that replies on the correct Ethernet port.

    The idea is simple, we have very powerful servers that can handle many requests, more requests that one Ethernet port can handle. In other words, we could have 2, 3, 4, probably even 10 Ethernet connections (it really depends on your application, of course: how much RAM you need, how much processing is necessary for each access, etc.)

    The solution is to use the ip command line which allows us to add default gateways for each ethernet card based on the ...

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Diverse Realty Team

Want a New Home?
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  • number

    All software make use of numbers. Everything is a number. The most basic number in a computer is 0 or 1. This is called a bit. These are represented with electricity. Although in most cases we see it as 0 - Ground and 1 - Voltage (i.e. 1 volt), the bit representation in software and in hardware may be interpreted either way (i.e. a 0 could mean that the voltage is 1V and not 0V.)

    Combining these zeroes and ones we offer end users to handle much larger numbers. With 8 bits, you can have numbers from 0 to 255 (unsigned) or -128 to +127 (signed.) Now a day, computers can handle a much larger number of bits in one cycle. Most processors use 64 bits but they can calculate numbers on 128, 256, and for some 1024 bits at once. Also with parallelism, the size can be viewed as even larger (i.e. handling a 64 bit number in 1,536 threads like on my old nVidra Quadro 600 is equivalent to one large number of 98,304 bits! That would be 2 power 98,304 possibilitie or about 2.8359e+29592 in decimal.)

    Integers are easy to handle. Although when working on math problems you generally see the set of avaialble numbers as equivalent to N although mathematicians know that computers can really only handle a limited set of numbers. For example, on a 64 bit computer, the usual range is -9223372036854775808 to 9223372036854775807, This is generally enough although at times some equations have to be reworked to avoid really large or small intermediate numbers that work fine in math equations, but not so well on computers.

    Now, math also includes other sets of numbers such as D, R, and C. Computers do not offer any way to represent numbers in R or C but they can offer D to some extend. These numbers are called floating point numbers because we do math using an exponent. The exponent makes the decimal point "float" in any location as the number used for the exponent offers. Using a 64 bit floating point, you can have positive and negative numbers with precision varing betwee 10-308 and 10+308. This includes a positive zero (+0) and a negative zero (-0), which is import in a few cases (although +0 = -0 is true, you can get the sign of a number and distinguish both zeroes). Note that at first decimal numbers were going to also have a positive and negative zero, but it was instead decided to have one more negative number (remember, with 8 bits we have signed numbers from -128 to +127, this is because in the positive numbers we have a 0 which we don't have in the negative numbers.)

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