How to get certificate thumbprint using openssl

November 09, 2016

Author's note: this is an older article I brought over from my prior blog by popular request. Some of the information may be a little dated.

I was troubleshooting a certificate issue today that required me to verify the thumbprint of a leaf cert. The challenge? I was working from console connection and couldn't copy/paste . . .

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sendmail Daemon Behavior During Restarts

July 25, 2016

An interesting question came up the other day: What exactly does the sendmail daemon do with SMTP sessions that are in progress when it needs to restart?

For the purpose of discussion, let's assume that it's being restarted via service sendmail restart. I'll wait a moment for admins to scream at their monitors about this . . .

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Spicy Bacon Tator Tots Recipe

Pretty much the best thing ever.

May 27, 2016

Alright folks, here's the recipe for some ridiculously good tater tots (respectfully modeled after a favorite dish at a nearby sandwich shop).

Ingredients:

  • 6-7 oz of sharp cheddar cheese (grated)
  • 1 package of tater tots
  • 1 habanero pepper
  • 4 Tbsp of salted butter
  • 6-8 strips of thick-cut bacon
  • . . .

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How to increase sendmail queue runner check interval

August 04, 2015

Author's note: this is an older article I brought over from my prior blog by popular request. Some of the information may be a little dated.

By default, sendmail will attempt to process/retry deferred messages in hourly intervals. For most environments, that's usually fine. However, some admins may want sendmail to try more . . .

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How to implement max file size limits and "log rotation" with tcpdump

July 10, 2013

Author's note: this is an older article I brought over from my prior blog by popular request. Some of the information may be a little dated.

Writing this down so I don't forget.

The issue: You need to collect a packet capture for an extended amount of time but don't want it to consume too much disk space.

. . .

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How to use sendmail debug switches to troubleshoot deferred messages

More information than you ever wanted to know about sendmail debugging

April 24, 2013

Author's note: this is an older article I brought over from my prior blog by popular request. Some of the information may be a little dated.

The problem: You need to troubleshoot low-level details concerning a deferred message in sendmail but don't want to necessarily increase global log levels (or restart services).

. . .

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