Archive
Posts from 2006
Microsoft Word is broadcasting on my network!
While performing some basic traffic analysis on my home wireless network, I noticed the folllowing broadcast traffic: Gak! I disabled rendezous on my laptop to avoid polluting the ether, and the applications that were running shouldn't be broadcasting messages! I was curious to see what was causing this, so I went into discovery mode. After reviewing ktrace, netstat and lsof data, I realized that the traffic was coming from Microsoft Word…
$ read more →Generating E-mail when Solaris security patches are available
I wrote about pca a few weeks back, and absolutely love the capabilities it brings to the table. To keep my servers up date with the latest security patches, I added the following cron job to extract security patches from the pca output, and E-mail them to my account: This works pretty well, and I now get E-mailed when security patches are available.
$ read more →Testing postfix restrictions
The postfix mail delivery system allows one or more restrictions to be placed on incoming messages. These restrictions allow you to block messages when clients don't use the SMTP handshake as outlined in RFC 821 during delivery, if the name supplied in the HELO is not fully qualified or fails to resolve, or if the connecting host resides on one or more blacklists. Several restrictions come enabled by default, but others need to be manually enabled by adding additional directives to the smtpd_helo_restrictions, smtpd_sender_restrictions and smtpd_recipient_restrictions variables. Since new restrictions can have unexpected results (e.g., lost E-mail), it is beneficial to test these rules prior to enforcing them…
$ read more →Implementing backoff timers in RSS readers
I have recently been on a quest to find a new RSS reader for OS X. NetNewsWire looks to be the leading candidate, since LifeRea doesn't have a native port to OS X. One thing I noticed in the clients I tested, is that they have fixed times when they will check ALL feeds for new content. This time increment can be in minutes, hours, days, weeks or months…
$ read more →Understanding MySQL performance data with mysqlreport
MySQL maintains numerous operational metrics (e.g., connections, questions, etc), which can be accessed by running 'show status' or one of it's variants from the mysql client. The mysqlreport Perl script can be used to summarize this data into a nicely formatted report with several useful performance metrics: The output from mysqlreport includes metrics on key cache and query cache utilization, the number of operations (SELECT, UPDATE, etc.) performed, thread utilization, connection volumes, table locks, and the types of temporary tables used by sorts. The folks over at hackmysql provide a nice writeup on what each report means, and the typical value ranges you should see in each report. Running mysqlreport is a great way to get a high-level understanding of how a database is performing, and can greatly assist with identifying the areas that are worth reviewing in greater detail.
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