Archive for December, 2006

Using ZFS clones to simplify upgrades

One cool ZFS feature that was introduced in Solaris 10 11/06 is the ability to clone a file system. This is a truly powerful tool, since it allows admins to create copies of file systems prior to performing upgrades, and a way to roll a file system back to a previous state (this provides a […]

Disabling old wordpress comments

As with most individuals that manage a blog, I get inundated with comment spam. Based on some research I did, it looks like almost all of the blog spam occurs for older posts, especially those over 30 days old. Based on this information, I decided to disable comments for all old posts older than 30 […]

Configuring crontab mail destinations with MAILTO

When scripts executing from cron write to stdout or stderr, the results are emailed to the user the job is running in the context of. One way to control where the mail is sent is by adding a “MAILTO” line to the top of the crontab entry for the user that is running the cron […]

Verifying GPG signatures

One of my friends recently asked me how to verify a signature that is distributed with an opensource application. Since I didn’t have a machine handy to show him, I thought I would jot this down for him in my blog. The first step in verifying a signature requires locating the public key of the […]

Securing CentOS Linux installations by disabling unneeded services

To ensure that my CentOS machines run as efficiently and securely as possible, I disable a number of services after each installation. The end result is a system that accepts ssh connections on TCP port 22, and on one or more service ports that are in use by the applications hosted on the platform. To […]

Viewing Linux partitions with fdisk and partprobe

While reading up on the Linux parted utility, I came across partprobe. Partprobe can be used to display the number of partitions on a device, and is useful for quickly viewing the layout of a given device: $ /sbin/partprobe -s /dev/hda /dev/hda: msdos partitions 1 2 If your looking for details on the layout of […]

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