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Archive for the ‘Computers’ Category

Nagios Error “HTTP WARNING: HTTP/1.1 403 Forbidden”

May 18th, 2011 2 comments

When monitoring websites with Nagios, it’s common to get the error “HTTP WARNING: HTTP/1.1 403 Forbidden“.

Quick Solution

Use the -H option to specify the host name for the web site e.g.

define service{
	use                     generic-service
	host_name               andymadge.com
	service_description     HTTP
	check_command           check_http!-H www.andymadge.com
}
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Categories: Computers Tags:

Fixing Extra Newlines in Text Files

September 11th, 2010 Comments off

When editing source code you often come across files with additional blank lines that shouldn’t be there.

Extra blank lines

The problem is generally caused by someone editing the file with a text editor which doesn’t understand and maintain the different newline types. You then end up with a file containing a mix of different line endings. Read more…

Categories: Programming Tags:

Password Salting Techniques

August 9th, 2009 3 comments

This article is about using salting techniques to improve the security of authentication for websites.  Examples are in PHP but the techniques apply to any language. Read more…

Categories: Computers, Security, Web Development Tags:

Missing tooltips in Firefox 3.5 and IE8

July 5th, 2009 2 comments

I’ve just upgraded to Firefox 3.5 and noticed that tooltips had stopped working.  I then checked Internet Explorer 8 and found tooltips were not working there either.

On investigation it seems that the two problems were unrelated, but here are the solutions to both of them… Read more…

Categories: Computers Tags:

Run SysInternals tools direct from the web

January 22nd, 2009 Comments off

SysInternals tools are a fantastic set of free utilities written by Mark Russinovich and Bryce Cogswell.  There are invaluable for system admins and Windows Power Users.
There is now a website that allows you to run most of the SysInternals tools directly, so you don’t have to find the right page, download it and unzip.  You just run it directly from:

http://live.sysinternals.com/<tool>.exe

e.g.

http://live.sysinternals.com/procexp.exe

This works better in Internet Explorer than Firefox, since you can run the tool without saving it first.

Categories: Computers, Windows Tags:

DOS Equivalent of GREP

September 22nd, 2008 Comments off

In Unix you can pipe the output of a command into the GREP command in order to only display the lines that contain a required string.  This is means you don’t have to scroll through pages of output to find the bit you’re interested in.  The DOS equivalent of GREP is FIND:

Searches for a text string in a file or files.

FIND [/V] [/C] [/N] [/I] [/OFF[LINE]] "string" [[drive:][path]filename[ ...]]

/V         Displays all lines NOT containing the specified string.
/C         Displays only the count of lines containing the string.
/N         Displays line numbers with the displayed lines.
/I         Ignores the case of characters when searching for the string.
/OFF[LINE] Do not skip files with offline attribute set.
"string"   Specifies the text string to find.
[drive:][path]filename
Specifies a file or files to search.

If a path is not specified, FIND searches the text typed at the prompt
or piped from another command.

this can be useful with the netstat command:

netstat -ano | find /i ":80"

or when viewing the DNS cache:

ipconfig /displaydns | find /i "google"

Although that isn’t ideal since the output of ipconfig isn’t really formatted to play nicely with the find command.

Reference: http://nzpcmad.blogspot.com/2007/07/dos-grep-equivalent-find-command.html

Categories: Computers, Windows Tags:

Windows XP DNS Cache

August 27th, 2008 Comments off

Windows caches DNS responses to speed up network access, but sometimes this can cause a problem.  Positive responses (i.e. successful lookups) are cached for 24 hours, and negative responses (i.e. failed lookups) for 5 minutes.

If you make changes to DNS and want to test the results straight away, you need to clear the cache with:

ipconfig /flushdns

You can view the current cache with:

ipconfig /displaydns

or

ipconfig /displaydns | more

to see a screen at a time

Categories: Computers, Windows Tags:

Mac OS X keyboard shortcuts

July 14th, 2008 Comments off

Useful OS X keyboard shortcuts, particularly if you’re switching from Windows.  It’s not exhaustive, but it’s got the ones I use regularly.

This page will be updated as I find new ones to include.

Read more…

Categories: Computers, Keyboard Shortcuts, OS X Tags:

Recover Deleted Photos from Memory Card

July 6th, 2008 Comments off

This article is written from the point of view of recovering deleted photos from a digital camera memory card, but most of the software will work to recover any type of file from any disk drive.

The first thing you must do is stop using the memory card.  The more you use the card, the less likely that you will be able to recover the photos.

There are loads of free utilities that will recover photos, and I suggest trying them in the following order:

  1. Zero Assumption Recovery
  2. Recuva
    • Download here
    • Install it and follow the wizard which guides you through the recovery process
  3. Undelete Plus

If you’ve tried all of those and been unsuccessful, then I’m afraid it’s not looking very promising, but if you want to continue trying here are a few more utils:

Categories: Computers, Software Tags:

Online & Peer-To-Peer Backup

June 20th, 2008 3 comments

I’ve been assessing various backup options for both business and personal use recently so here’s a summary of my findings

Read more…

Categories: Computers, Software Tags: