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Apparently, a recent Red Hat Enterprise Linux update for ES3, 4 and 5 caused some Perl applications to throw errors like these:

A few days ago, I stumbled upon a server running qmail with qmail-scanner.

By default, Red Hat Enterprise Linux 4 sets the default character set in Apache to UTF-8.

I found myself wrestling with a server where the Plesk interface suddenly became unavailable without any user intervention.

Create a strong CSR and private key

I’ve struggled at times to get a decent-looking terminal on my desktop, and I believe I’ve found a good one.

Here’s a pretty weird kernel panic that I came across the other day:

A few days ago, I began to install a group of packages with up2date, and the person next to me was surprised that up2date even had this functionality.

If you’re using Plesk 8.

When you dump table data from MySQL, you may end up pulling a large chunk of data and it may exceed the MySQL client’s max_allowed_packet variable.

I was recently working on a server where a user on the server was concerned with these log messages:

In some situations with dovecot running on your server, you may receive a message from your e-mail client stating that the “connection was interrupted with your mail server” or the “login process failed”.

On brand new Plesk 8.

I’ve seen quite a few situations where the Horde login process can take upwards of 45 minutes to log a user into the webmail interface.

One of the most annoying (and explosive) changes in Plesk 8.

If you want to convert a MyISAM table to InnoDB, the process is fairly easy, but you can do something extra to speed things up.

Yet another weird Plesk error with terrible grammar popped up on a server that I worked with this week:

Normally, this error will pop up when you attempt to restart a Plesk-related service, like httpsd, psa-spamassassin or qmail:

Some users will want to parse HTML through the PHP parser because one of their applications requires it, or because they think it’s a good idea.

Since AOL sends their users’ traffic through proxy servers, this can cause problems with Horde’s session handling in Plesk.

In the event that your system is running out of file descriptors, or you simply want to know what your users are doing, you can review their count of open files by running this command:

If you want to adjust how long postfix will hold a piece of undeliverable mail in its queue, just adjust bounce_queue_lifetime.

With RHEL 5 ditching up2date for yum, many Red Hat users might find themselves confused with the new command line flags.

If you have SpamAssassin installed, but you want to make sure that it is marking or filtering your e-mails, simply send an e-mail which contains the special line provided here:

When you create a CSR and private key to obtain an SSL certificate, the private key has some internal data called a modulus.

By default, Red Hat Enterprise Linux 2.

When you find yourself in a pinch, and you don’t know the limits of a certain Red Hat Enterprise Linux version, you can find this information in one place.

So, this is not really related to the normal system administration topics discussed here, but it’s Sunday, so I feel like something different.

We all enjoy having the GoogleBot and other search engine robots index our sites as it brings us higher on search engines, but it’s annoying when some user scrapes your site for their own benefit.

If you’ve run MySQL in a replication environment, or if you’ve enabled binary logging for transactional integrity, you know that the binary logs can grow rather quickly.

I hear a lot of complaints about Plesk’s backup routines and how they can bring a server to its knees.

If an .

Let’s say you have a user who can’t receive e-mail.

Lots of PCI Compliance and vulnerability scan vendors will complain about TRACE and TRACK methods being enabled on your server.

If you find yourself in a pinch and you need a temporary fix when your primary IP is blacklisted, use the following iptables rule:

This error completely stumped me a couple of weeks ago.

This error will pop up when binary logging is enabled, and someone thought it was a good idea to remove binary logs from the filesystem:

When connecting to your server’s POP3 service, your client might provide this error just after authentication:

It’s not abnormal for qmail act oddly at times with Plesk, and sometimes it can use 100% of the CPU.

If you have to use short e-mail usernames in Plesk (which is a bad idea), and someone accidentally sets the server to use full usernames, you can force Plesk to go back.

While running into MySQL’s open files limit will manifest itself into various error messages, this is the standard one that you’ll receive during a mysqldump:

By default, views in MySQL 5.

Sometimes MySQL’s process list will fill with unauthenticated login entries that look like this:

Help me out!

I’ve been flooded with requests for MySQLTuner and I’ve answered them this weekend.

In some situations, you may want to have domain.

With Plesk 7.

Urchin sometimes takes it upon itself to do some weird things, and this is one of those times.

An often misused and misunderstood aspect of MySQL is the query cache.

Should you find yourself in the situation where you’ve forgotten the Urchin admin password, don’t worry.