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Displaying posts with tag: Sysadmin (reset)

SFTP virtual users with ProFTPD and Rails: Part 1
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I recently worked on a Rails 3.2 project that used the sweet PLupload JavaScript/Flash upload tool to upload files to the web app. To make it easier for users to upload large and/or remote files to the app, we also wanted to let them upload via SFTP. The catch was, our users didn't have SFTP accounts on our server and we didn't want to get into the business of creating and managing SFTP accounts. Enter: ProFTPD and virtual users.

ProFTPD's virtual users concept allows you to point ProFTPD at a SQL database for your user and group authentication. This means SFTP logins don't need actual system logins (although you can mix and match if you want). Naturally, this is perfect for dynamically creating and

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Mailbox conversion
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Converting from uw-mailboxes (mbx) to Unix format (dovecot)

It took me by surprise how the mailbox formats had changed, when I switched to Dovecot which is the best IMAP/POP3 mail program, in my opinion. It handles large (enormous) mailboxes with many (hundreds of) users. Caching makes things go fast again.

Here is a simple bash utility, to take all users, and convert all mailboxes & folders.

cd /home
for u in *
do
if [ -d /home/$u/Mail ]; then
echo "User: $u"
cd /home/$u/Mail

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Tools: What file system?
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On Linux, you have a plethora of File Systems available.

Recently I was testing databases (MySQL, MariaDB) especially with ThreadPool against a Violin Flash Memory Array, and I forgot what file system the LUN was mounted (and formatted) as.

There are two ways to find out:

  • df -T (show mounted life systems, along with the FS type)
  • file -s /dev/xxx (show more details about a FS node)

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Net tools
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A set of internet tools, is available at otala.net/tools.shtml

  • Traceroute
  • Whois & JWhois
  • NSLookup
  • Ping
  • DNSWalk
  • NetStat
  • ENUM (e164.org phone number lookup)

More to come, as (if/when) I get time -- suggestions welcome

What a Hosting Provider did Today
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I found Dennis the Menace, he now has a job as system administrator for a hosting company. Scenario: client has a problem with a server becoming unavailable (cause unknown) and has it restarted. MySQL had some page corruption in the InnoDB tablespace. The hosting provider, being really helpful, goes in as root and first deletes ib_logfile* then ib* in /var/lib/mysql. He later says “I am sorry if I deleted it. I thought I deleted the log only. Sorry again.”  Now this may appear nice, but people who know what they’re doing with MySQL will realise that deleting the iblogfiles actually destroys data also. MySQL of course screams loudly that while it has FRM files it can’t find the tables. No kidding! Then, while he’s been told to not touch anything any more, and I’m trying to see if I can recover the deleted files on ext3 filesystem (yes there are tools  [Read more...]
What's New in CFEngine 3: Making System Administration Even More Powerful
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CFEngine is both the oldest and the newest of the popular tools for automating site administration. Mark Burgess invented it as a free software project in 1993, and years later, as deployments in the field outgrew its original design he gave it a complete rethink and developed the powerful concept of promise theory to make it modular and maintainable. In this guise as version 3, CFEngine stands along with two other pieces of free software, Puppet and Chef, as key parts of enterprise computing. Along the way, Burgess also started a commercial venture, CFEngine AS, that maintains both the open source and proprietary versions of CFEngine.

Diego Zamboni has recently taken the position of Senior Security Advisor at CFEngine AS and is writing


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Things I didn't know you could do with top...
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My colleague Mike Hamrick, who I'm very fortunate to work with, made a presentation on some cool things you can do with top: http://tinyurl.com/48pmu83. These are some great tips that every MySQL DBA or developer should watch!
Keeping Up
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I found I never published this post as it was sitting in my drafts few months now — it was written in 13th February, 2010. I’m publishing it without any changes.

I learn therefore I am!

I’ve just wrote few bits about learning a new technology and after skimming through my Google Reader, I noticed a great post by Chen Shapira — Deliberate Practice. That’s reminded me about another aspect of learning that I didn’t mention — learning is a continuous process.

There are two aspects…

  • No matter how good I am and how much I know, my knowledge and expertize become outdated relatively quickly these days unless I keep up with the
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An SSH tool to make your life easier
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A MySQL user group member saw that I use Poderosa as my ssh-on-Windows tool, and asked why I did not use PuTTY. My response was that I like having tabbed windows and hate having to keep opening another PuTTY program every time I want to open another connection. With Poderosa I can open a new connection with Alt-N, and I can even connect directly to Cygwin with an icon.

But Poderosa is not the tool I wanted to mention….Another user group member mentioned PuTTY Connection Manager. It wraps around PuTTY and gets the existing saved connections, makes a nicely tabbed browsing window where you can open sessions by double-clicking the connections, which are now listed on the right-hand side.

See screenshot below:

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Liveblogging: Senior Skills: Sysadmin Patterns
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The Beacon Pattern:
- This is a “Get out of the business” pattern
- Identify an oft-occurring and annoying task
- Automate and document it to the point of being able to hand it off to someone far less technical

Example:
- System admins were being put in charge of scheduling rooms in the building
- They wrote a PHP web application to help them automate the task
- They refined the app, documented how to use it, and handed it off to a secretary
- They have to maintain the app, but it’s far less work.

The Community Pattern:

- Prior to launch of a new service, create user documentation for it.
- Point a few early adopters at the documentation and see if they can use the service with minimal support
- Use feedback to improve documentation, and the service
- Upon launch, create a mailing list, forum,











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Showing entries 1 to 10 of 66 10 Older Entries

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