Posts Tagged ‘capability’

How to check if newly installed SSL certificate for IMAP and IMAPS is properly installed

Tuesday, June 28th, 2011

Did you have to regenerate your SSL certificate for your mail server’s IMAP and IMAP SSL service?
Did you have to find out if the newly installed certificates are fine after install?

Here is how:

          root@server-hosting [/usr/local ]# openssl s_client -connect imap.example.com:993
root@server-hosting [/usr/local ]# openssl s_client -connect imap.example.com:143 -starttls imap

The output returned by this two commands will be the imap and imaps configured certificates as well as extensive info concerning the installed SSL, the last chunk of info to be spit is most crucial to know if certificate is fine.
It should be something like:

...
New, TLSv1/SSLv3, Cipher is AES256-SHA
Server public key is 1024 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
Protocol : TLSv1
Cipher : AES256-SHA
Session-ID: 0B69E91022CB56D64F56CFA08405944D9C4C0069EE4097890B98F1406CF084D5
Session-ID-ctx:
Master-Key: 13745B94E0C5A0604EB7529E7409251961DFD5F4134F3A8F
Key-Arg : None
Start Time: 1309265383
Timeout : 300 (sec)
Verify return code: 18 (self signed certificate)
---
. OK CAPABILITY completed
closed

Reboot Safely a frozen (hanged up) Linux Server with Magic SysRQ Key combination

Monday, June 20th, 2011

Linux Magic SysRQ Key picture

Being a remote system administrator for many years from now, I’ve experienced many times sudden Linux crashes, mostly caused by system hardware overloads.

This is a common thing especially on busy Web Servers with (Apache/MySQL). Situations like this are really messy and many times in order to bringt the server back online, one has to either physically go to the Data Center or contact the Technical support to request a server reboot.

In this terrible times, data loss might occur if the Server reset button is used to cold reboot it.

Happily in 99% of the cases the data loss which might occur could be prevented with Linux’s kernel capability to support the Magic SysRQ key !

Having the Magic SysRQ key functionality being supported in Linux in past times wasn’t that common, thanksfully these days this has changed andlmost every Linux distrubution supports this handy feature.

Now you might wonder what is the magic with those Magic SysRQ key ?

Let me explain, Magic SysRQ is a kernel level functionality which supports even completely crashed Linux systems with the horrifying:

Kernel Panic
message to be properly shutdown.

Using Magic SysRQ instead of the mostly used indiced cold reboots is really advantageous, as all the opened files by programs on the crashed server which hanged will be properly saved and closed and thus possible data loss caused by the sudden server crash will be minimized.

One other good thing about the Magic SysRQ Key keyboard combination is that initiating the Magic SysRQ could be made blindly (no need for server monitor or display to present any error messages on the failed server).

Now to check if the magic sysrq is enabled on a server one should issue the command:

Here are some Magic SysRQ keyboard combinations one can use in case of server failure:

ALT+SYSRQ+M to dump memory info;
ALT+SYSRQ+P to dump processes states;
ALT+SYSRQ+S to sync disks;
ALT+SYSRQ+U to unmount all mounted filesystems;
ALT+SYSRQ+E to terminate processes;
ALT+SYSRQ+I to kill all processes
ALT+SYSRQ+U to try to unmount once again;
ALT+SYSRQ+B to reboot.

I would skip to explain what each of the keyboard combinations will do as I believe the above description explains it well.

One classics of combinations one might want to issue on a failed Linux server supporting the Magic SysRQ would be:

ALT+SYSRQ+R
ALT+SYSRQ+E
ALT+SYSRQ+I
ALT+SYSRQ+S
ALT+SYSRQ+U
ALT+SYSRQ+B

The ALT+SYSRQ+REISUB key combination is very popular among system administrators.
Also Magic SysRQ is heavily used by kernel developers as it includes many handy debugging options.

If you try the Magic SysRQ key on older servers and you realize it doesn’t react you will have to recompile the linux kernel and enable the CONFIG_MAGIC_SYSRQ kernel time compilation option.

The Magic SysRQ can also be initiated remotely on a properly running server 😉 by initiating:

server:~# echo b > /proc/sysrq-trigger

This command would be useful if you want to just have fun and test that magic sysrq works on your system for sure 😉

To sum it up using the Magic SysRQ will guarantee your locked up, server a Safe Reboot and will hopefully save you a lot of time for backups recovery.

What is Xorg’s server DPMS module for? And how to use it to reduce your computer power consumption

Thursday, April 21st, 2011

As I’m manually configuring a Xserver via xorg.conf I have noticed a block of code in:

Section "Monitor"
Identified "Generic Monitor"
Option "DPMS"
EndSection
That triggered my curiousity to research further what is DPMS . A very quick google search revealed that DPMS’s purpose is to communicate to communicate between the monitor and the computer, to make the computer turn off the (CRT or LED) based monitor if the computer is not used

Thus in short to rephrase DPMS is a power saving handy Xorg feature. I many custom configured xorg.conf like the mine I’m building right now does not include DPMS as many people doesn’t have idea what DPMS is and how to enable it.

DPMS is also an interface to the Energy start power-saving capability if not all, most of the modern day monitor screens.

DPMS enables the Xserver to control automatically the computer screen and thus reduces the overall computer power consumption.

To enable the use of DPMS on my Linux, all I had to do is place a couple of configuration directives in my xorg.conf .:
Here is how I enabled DPMS in my Xorg server:

1. Edit with a text editor /etc/X11/xorg.conf

2. Find the Monitor Section , e.g.:

Section "Monitor"
....
EndSection

3. Add inside the Monitor Section Options "DPMS" "true"

4. Lookup for the ServeryLayout section , e.g.:

Section "ServerLayout"
...
EndSection

5. Place inside the ServerLayout section For instance the following options:

Option "StandbyTime" "20"
Option "SuspendTime" "10"
Option "OffTime "25"

You might like to change the options StandbyTime, SuspendTIme or OffTime to match your likings.
6. As a last step restart the Xorg server.

Press Ctrl+Alt+BackSpace or by issuing:

host:~# pkill -HUP X

Test that DPMS is loaded properly by reviewing /var/log/Xorg.0.log for example:

host:~# grep -i /var/log/Xorg.0.log
(II) Loading extensions DPMS

Drawing GANTT Charts and Project Management on Linux, (Microsoft Project substitute for Unix)

Tuesday, October 12th, 2010

I'm studying Project Management, right now. In that spirit of thoughts I and a couple of other guys are building a Project Plan.
As it Project Plan it's necessary to put a GANTT Chart in it to show visually the project timeline (the phases), the duration and the inter-relation between the different tasks which leads the project to an actual completion.

After a bit of thorough research online on available software to deal with project management and particularly, ones that are capable to build a GANTT charts on Linux / BSD.

I've come with the following list of software capable to be a substitute for the Microsoft Project software.
Redmine GANTT Chart

GANTT chart Redmine

1. Gantt Project
GANTTProject chart GANTTProject Chart

2. Gnome Planner
Planner GANTT Gnome Chart Planner GANTT Chone Chart

3. Task Juggler Project Manager with GANTT Capability for (KDE)
Task Juggler

4. JxProject – This software is not free, though it can be considered almost free
Take a look also at:
5. Trac , though it doesn't really support GANTT charts it's a lovely software to be used for PM.
Trac Project Management

Another option you have is to try out:
6. PHProjekt

Update 20.09.2016 – PHPProject Old download link is no longer active

It is this link http://www.phprojekt.com/, but the page doesn’t seem to be active any more. I thought you might want to update.

If you are looking for an alternative please check out http://wiht.link/PHProjekt-PM, it may make a suitable replacement.

Kind Regards,
Tom Wilcox


That piece of softwre really looks promising, especially if we consider that it's web based and how much essential is today to have an anline tools for doing the ordinary desktop jobs.

You can even check an online demo of the PHPProjekt software here

If you're a type of KDE user you definitely has to try out Kplato

As I've tested the software the software is easy to be used, however it still is missing some essential parts that Microsoft Project includes so it's not 100% substitute.
Also it's not able to open Microsoft Project (MPP) files, neither able to save the charts in the .mpp format.

Moving ahead I've came across DotProject DotProject Gantt Chart
DottProject Gantt Chart

I haven't took the time to test it myself but however, as I go through the software website the project looked quite good.
Lastly you can take a look at: 7. PStricks as a mean of project management, however I think it doesn't support GANTT chart building.
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