Exchange 2010 and 530 5.7.1 Client was not authenticated error

My Exchange server is behind a Linux firewall with sendmail fronting the email handling. I started seeing messages in the maillog on the Linux machine like:
dsn=4.0.0, stat=Deferred: Connection reset by <em>mailserver</em>.

Following that were even odder messages from SpamAssassin:

<em>mailhost</em> mimedefang-multiplexor[1614]: Slave 0 stderr: dns: sendto() failed: Connection refused at /usr/lib/perl5/vendor_perl/5.10.0/Mail/SpamAssassin/DnsResolver.pm line 411.
<em>mailhost</em> mimedefang-multiplexor[1614]: Slave 0 stderr: Use of uninitialized value in string ne at /usr/lib/perl5/vendor_perl/5.10.0/Mail/SpamAssassin/AsyncLoop.pm line 174.
<em>mailhost</em> mimedefang-multiplexor[1614]: Slave 0 stderr: plugin: eval failed: oops, no key at /usr/lib/perl5/vendor_perl/5.10.0/Mail/SpamAssassin/AsyncLoop.pm line 174.

This was all due to the added security of the Exchange Server installation (I believe it is also true for 2007). It is set up for authenticated connections and to disallow anonymous connections.

To resolve, I added a new Receive Connector in the Exchange Management Console for my sendmail front end machine under Hub Transport in the Server Configuration. I set this up to only receive mail from the IP Address for my sendmail machine and checked the Anonymous users permission group. Adding this new Receive Connector allowed email to be received from my sendmail machine once again.

In simpler terms:

1. Open Exchange Management Console
2. Click on Hub Transport under Server Configuration
3. Click on the corresponding hub in the top section
4. Right-click on the bottom section and add New Receive Connector
5. Using Custom as the intended use:
1. Listen on Port 25
2. Enter the desired FQDN
3. Edit the IP Range to match the address of the sendmail machine
4. Create the New Reveice Connector
6. After the Receive Connector is created, right-click on it and select Properties
7. On the Permission Groups Properties tab, select Anonymous users and press OK

A working system!

Windows Server 2008 R2 stuck during boot at Applying computer settings…

Rebooted the server last night and the screen would not get past Applying computer settings… There seemed to be very light disk activity. I discovered that if I rebooted in Safe Mode with Networking and re-enabled the IPv6 on my Local Area Connection, the system would boot normally. I had turned it off earlier but had not rebooted since that change.

Steps:

1. Right click on my network connection in the system tray and select Open Network and Sharing Center
2. Display the Local Area Connection Status
3. Click Properties and make sure Internet Protocol Version 6 (TCP/IPv6) is checked
4. Quit everything and reboot

The only other potential factor was the server was behind a NAT; it could communicate with the local network but could not reach the outside world due to a misconfiguration in the firewall.

Problem upgrading my WinXP image to Parallels 4 (+ solution!)

I’ve been struggling trying to upgrade my WinXP image after installing Parallels for on my MacBookPro. Every time I go to install Parallel tools, it just hangs after a while. Problem is that Windows thinks the underlying hardware has changed significantly so it is asking to re-activate the software.

At first, I didn’t have mouse access so I tried once again to install Parallel Tools; it hung again this time but after Force Quitting it, I had mouse and network access. Next I started the VM again and activated Windows. After that completed successfully, I was able to install Parallel Tools.

Google Chrome

Don’t most operating systems start with a command line? And what really is the Omnibox? I think it is the basis for the command line of the Internet.

What Technical Tests Do You Give Potential Hires?

I’m amazed at how many candidates I’ve interviewed cannot provide an elegant solution to the following test:

Write a routine, in your favorite language or even a mock language, without using an intrinsic function to solve the problem for you, to reverse the contents of a string. The routine should take an input of a string and output a string. For example, if the input is “hello” the output should be “olleh”.

I inform the candidate that it is a simple problem and invite them to talk through their logic as they write their solution on the whiteboard. I let them know it does not have to be syntactically correct; I am more interested in their approach.

It is enlightening, to say the least, to watch interviewees attack this problem. I’ve actually had so many people fail that I’ve been questioned if my “test” was too difficult. I understand there are abnormal pressures in play due to the setting but employees should ultimately perform decently under some pressure.

Silently I watch and listen to the candidate attempt to solve the problem. When the candidate is finished I usually ask, with good reason, are you certain this solution is correct? The response is often a “yes.” This usually gives us ample opportunity to talk about different strategies and try to understand why it was coded in a particular method.

I notice lots of issues that should not occur; for example, the candidate:

• does not understand the chosen language or it’s string libraries.
• has issues with zero-based arrays depending on chosen language.
• overly complicates the approach and never sits back to re-evaluate.
• can not come up with a solution.
• chooses a complicated approach involving math and gets the math wrong.
• uses too many variables.
• writes unnecessary code that essentially does nothing.
• can not validate the output of the routine they wrote correctly.
• writes more than ten lines of code to solve the problem.
• does not know how to swap values in to variables properly.
• … and many more.

I’d appreciate others offering this simple test and sharing your results with me and everyone else. I’d also like to know your thoughts the validity of this test and how you would let the results affect your view of the candidate.

Before reading on to see my solution, try it for yourself. Let me know how you do.
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