Category Archives: Technology

DKIM Rule – SpamAssassin

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I put together a new SpamAssassin rule that will help identify spam from spoofed email addresses.

Some email providers always sign email with DKIM or DomainKeys … based on this assumption, if you get a message from one of those domains and it isn’t signed, you can assume its more likely to be spam.

This particular rule operates on the assumption that all mail from Yahoo & Gmail will be signed.  It does not, however, raise the score a huge amount … because it’s just more LIKELY to be spam if it’s not signed … it’s not guaranteed to be spam. Some people may use the Yahoo or Gmail account’s in the from address, but not actually send from that service.
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Xen, LVM, and Grub

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I ran into an interesting problem with my new server the other day.

Due to a hardware problem with an external USB hard drive, I had to reboot the XEN host.

I had to do the reboot remotely … so I couldn’t intervene if something went wrong.  Yes, you guessed it, something did go wrong.

When I finally got home I found the system trying to boot ‘bree’ … which is one of the XEN guest machines.

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New Internet Provider

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Although it took more a lot longer to actually get around to making the change than I had planned on … I have finally switched Internet providers.

Previously I was using Covad for the midrange.com Internet service and AT&T for personal Internet service.

The Covad service was 1mb SDSL (1mb down / 1mb up with 5 static IP addresses) and the AT&T service was 6mb down & 768k up (ADSL).

The new service, provided by Comcast, is 22mb down / 5mb up and includes 13 static IP addresses.  It’s replacing both the Covad and AT&T service.

In addition to the improved speed, I’ll be saving about $50 / month in cost.

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CentOS Upgrade

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Well, I’m pretty pleased with CentOS so far.

I just completed a minor version upgrade (5.5 to 5.6) via yum and it went very smoothly.  This involved 3 virtual guest and one host (the guests run inside the host).

I had one small glitch with the RPM database on middle-earth.  Some dependencies were screwed up, but that was corrected by running yum clean all.

In order to speed things up, I’m going to be mirroring the most current CentOS package repository on middle-earth … that way I can get the updates done much quicker (installs too).

Of course I still have to move a bunch of the applications to the virtual machine’s.  I think I’m close to being able to retire gondor.  Moving rivendell is going to a major effort.

Epsilon

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By now everyone’s probably heard about the data breach at Epsilon … which resulted in a lot of major eCommerce vendors customers mailing list getting stolen.

Personally, I’ve gotten notifications from Chase, Walgreen, Tivo, Best Buy, 1-800-Flowers, and a few others … informing me of the breach and assuring me that no critical information was stolen … just my email address.

What do you do now?

Nothing, really.

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Virtualization Advice

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I need some virtualization advice.

I’m currently running this blog, among others, on XEN 3.1.2 based virtualization on CentOS 5.5.

At the present time, I have three physical machines running … rivendell, gondor, and middle-earth.

Middle-earth”is the XEN host.

Rivendell and gondor are stand alone servers running Fedodra 10.

Currently gondor is primarily a web server and backup mail delivery server.

Rivendell is the main system and acts as a NIS server, MySQL server, samba file server, chat server, mail server, etc.

My goal is to migrate all the functions from rivendell & gondor to XEN instances on middle-earth.

My questions relate to where to run services, file systems, and processor allocation.

Specifically …

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Confidential Information

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I saw a very interesting mail reject message today on one of my mailing lists …

You are receiving this message because you have attempted to send an e-mail containing confidential information. Examples of confidential information include, but are not limited to social security numbers, birth dates, account numbers, policy numbers, medical history, financial history, personal phone numbers and user IDs. Another example of sending confidential information would be combining any two or more of the following: name, address, identification numbers (employee number, phone number), organizational affiliation (place of employment). This information may be contained in the body of the message or any attachments.

I looked at the body of the message it was rejecting (which was included in it’s entirety), and noticed that the message referenced dummy social security numbers (the message discusses SQL techniques).

Of course, based on the warning message, it would probably reject ANY numeric text that was included in a message at all.

I suspect that the company, who’s server rejected the message, does not have a problem with email volume … since the majority of email sent to them is probably rejected.

I really wonder about companies that have such incredibly draconian content rules.  How do they stay in business?