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Thursday, April 26, 2012

Implementing SPF and DKIM in Mail System

How to use authorization in sending mails, as we know there is lot of spammers and phishers which exploit Mail Servers daily and not only this if you are sending Bluck Mails to your clients having mail ids in different domains (yahoo, gmail, hotmail etc) in most cases your mail will land on spam or junk, so to avoid these things we can implement SPF and DKIM.

First lets understand what is SFP and DKIM

Sender Policy Framework (SPF) is an email validation system designed to prevent email spam by detecting email spoofing, a common vulnerability, by verifying sender IP addresses. SPF allows administrators to specify which hosts are allowed to send mail from a given domain by creating a specific SPF record (or TXT record) in the Domain Name System (DNS). Mail exchangers use the DNS to check that mail from a given domain is being sent by a host sanctioned by that domain's administrators.

Domain Keys: DKIM embeds a cryptographic signature to e-mail messages and an indication of which DNS entry to examine. The receiving server can then look up the DNS entry and use the data it finds to verify the signature.

 To Generate SPF you can get help from Here or you can generate SPF through this  URL .

And to generate DKIM signature you can use this URL and if you are concerned about your Keys may be misused by above URL then you can generate DKIM Keys through OPENSSL to do this you can follow the steps from this Website

I hope this will help you out from some spamming frustration and there is another thing we can implement that is DMARC (Domain-based Message Authentication, Reporting & Conformance), we will talk about this in coming post....

Saturday, January 28, 2012

How to Trace Deadlocks in SQL Server

In SQL Server Trace flags are  used to diagnose performance issues or to debug stored procedures or complex computer systems.Trace flags are valuable DBA tools that allow you to enable or disable a database function temporarily. Once you turn on a trace flag, it remains on until you either manually turn it off or restart SQL Server. So to Trace Deadlocks in SQL Server we use two Trace Flags

1. 1222

Used to trace deadlocks in SQL Server.


DBCC TRACEON (1222,-1)

2. 3605

Used to write Deadlocks to Errorlog.


DBCC TRACEON (3605,-1)

So above two Trace Flags are enough to Trace Deadlocks in SQL Server Databases. To Disable above Trace Flags we have to use DBCC TRACEOFF command.