If you run a mail server (which I think everyone one should for a real decentralized communication network e-mail was originally designed for) and using postfix and use dnsbl.njabl.org to lookup blacklisted hosts when processing mail, then you need to remove this host as dnsbl.njabl.org has been sunset and will no longer resolve. This will affect your mail server as it will reject all mail received. Update your postfix configuration file /etc/postfix/main.cf and remove this RBL client entry e.g:
smtpd_client_restrictions = reject_rbl_client sbl.spamhaus.org, reject_rbl_client blackholes.easynet.nl
, reject_rbl_client dnsbl.njabl.org
Then restart your postfix server
Well now you don’t have to be at the mercy of the these remote servers and and their policies. Why not own your own personal server.. Set it up as an always on service that is there to serve you and your family.. set it up to provide you secure e-mail service, set it up as a personal cloud and use it to share and sync data from your client computers at home or office – your server in the privacy of your home.. give access to data to only whom you want – your data is only your business — use it to monitor and control your smart home – but without sending the data to the remote servers.
Check out the personal server from Pexus – Patriot PS – Personal Cloud & Automation Server – Get your data back in your home.. where it belongs– if somebody needs it give it on your terms ! We know this is a small step.. there is more to come.. more applications that will reside on your server and help you manage your data in your home. Come and be part of a new era in personal computing..
A recent article in IEEE Spectrum piqued my interest in Bitcoin – a P2P open source digital currency.
Another interesting introductory read available from this article from Wired Magazine: http://www.wired.com/magazine/2011/11/mf_bitcoin/all/1
All modern J2EE application are distributed in nature and typically involves web servers, application servers, database servers etc. . Diagnosing application problems in a distributed environment is challenging. Tracing problems as application requests and transactions traverses across the distributed components whether it is the web server, application server, database components is always time consuming and requires quite a bit of application knowledge. A number of monitoring tool software have promised the holy grail of transaction tracking and diagnosis but have largely failed. A lot of monitoring tools end up with large dashboards with red, yellow and green markers that just indicates if the system is running fine or has issues but not enough information to diagnose them quickly. Enterprises spend millions in licensing costs to monitor these distributed components only to spend more money on additional resources to diagnose and fix them. Most of monitoring tools end with operational teams that lack the deep knowledge to diagnose application problems quickly.
My years of experience diagnosing problems have helped me realize that to diagnose problems quickly one has to resort to application logs, stack traces, debug traces and some deep knowledge of application. Deep application monitoring tools such as Wily, ITCAM for Application Diagnostics etc. do offer deep instrumentation but have very high performance overheads when they are turned on always. Despite their deep tracing capabilities they still fall short of correlating the individual requests to provide meaning full insight to resolve problems quickly.
All application components have some kind of logs but obtaining the logs for application diagnosis from disparate systems and correlating log entries is a time consuming process.
Splunk log monitoring tool helps you search log files spread across disparate systems and organizes the results chronologically, by hosts, by log types etc., but by itself is not sufficient to help you correlate the log entries. Splunk tool offers a slightly different approach to application problem monitoring by helping scan application logs for error symptoms. However Splunk does require some prior knowledge of application exception handling and common error strings to look for. While Splunk is extremely powerful in scanning logs and displaying the log searches chronologically that can span the various distributed components, it still falls short of correlating them unless the application provides some unique identifier to tie the logs together. Building a logging framework that can be shared by the distributed application will help application diagnosis immensely.
All modern application frameworks provides some kind of mechanism to add filters to application requests or you can leverage aspect programming patterns to add contextual information as requests pass through the different layers of your application. Caching application traces for requests and printing them when requests exceeds response time threshold can greatly aid in application diagnostics.
I will be talking about such an implementation in Part 2 of this series, that leverages the Splunk deployment in our application infrastructure to enhance the performance and application diagnosis process.
Checkout links from Pexus Knowledge Hub related with IT, Open Source, Linux, iOS etc.
Ever wanted host your own application like DimDim, GoToMeeting etc. to share and collaborate with your teams on demand and not pay any subscription fees ? Look at the free open source alternative – BigBlueButton. If you have a Linux Server lying around, accessible on the internet or an Amazon EC2 account and a little savvy with Linux you could potentially host your own for almost free !
This X-Deep/32 X-Server FAQ talks about how you can leverage free Putty tool and minimalistic X Window package XFCE4 that you can install on Linux Servers such as Ubuntu Server etc, without overloading you Linux Servers running in a headless environment. Use with cost effective Pexus X-Deep/32 X-Server solution to access Linux servers securely for common administration tasks right from your Windows desktop. With X-Deep/32 you can start multiple sessions each with it’s own instance of X-Server.
If you are using Suse Linux Enterprise distribution, it is important you get your updates and patches from Novell to maintain your support and authenticity of your distribution.
Each distribution has it’s own quirks and if you have worked with a different distribution such as Red Hat, CentOS or Ubuntu, it takes a while to get around and be familiar with the updates, patches, repositories etc.
Novell has 3 distributions that may be useful for enterprise customers. Novel SLE JEOS (Suse Enterprise Linux Just Enough OS – slimmed down OS), Novell Suse Linux Enterprise (SLE) Server/Desktop and Novell Suse Linux Enterprise for VMware.
There is a new tool called zypper that lets you register and manage your updates and patch levels.
To register your product (applies to Novell Business Partners). you will have to get an activiation code. Login to your Novell site and based on your entitlements, you can obtain the registration code. Use the following command to register your SLE and refresh your zypper environment.
suse_register -a email=your_email -a regcode-sles=your_registration_code
After registration list the update repositories that are added to your zypper environment.
For more information refer:
On Linux (and UNIX) uname -a command gives the version of the kernel. Each distribution has it’s own version numbering.
For Suse SLE S/D if you want to find the version and patch level of your distribution, use the command – cat /etc/SuSE-release
Networking is the first thing you would do after installation of a Linux OS (for that matter any system OS). If you are dealing with a server, chances are you don’t have a GUI at hand. Most Linux distributions have different utilities to handle network configuration. Here are links to Novell Suse Enterprise Linux documentation.
All Novell Docs -> http://www.novell.com/documentation/index.html
SLE11 Network Configuration Link -> http://www.novell.com/documentation/sles11/book_sle_admin/data/sec_basicnet_manconf.html