X-Forwarded-For log filtering

The “X-Forwarded-For” is a HTTP header commonly used to pass the original client ip address as the web request traverses through reverse proxy servers. Furthermore, to truly capture the request ip address, the web server must be configured to record the ip address from the X-Forward-For header. If not, the log file will simply show that all requests are coming from the reverse proxy servers that frontend the web servers. (more…)

Configuring Sendmail to relay through Gmail SMTP

Sending email directly from the MTA (mail transfer agent) on one’s server is now considered to be faux pas. Unless you’ve got that machine configured within DNS (MX record, reverse lookup, etc), it’d likely fail most basic spam checks at the destination mail server. The complexity of the configuration increases if you’ve got the need to masquerade emails from multiple domains. (more…)

Dissecting Amazon Web Services

Just reading this article on AWS and thought I’d share some interesting numbers (in addition to the Quantcast data I shared earlier):

• 52 billion objects are stored in S3 and that S3 requests regularly peak at 80,000 requests per second.
• EC2 is experiencing monthly growth of “almost 10%.”
• Amazon has U.S. data centers in Dallas, Los Angeles, Miami, Newark, Palo Alto, Seattle, and St. Louis, and international data centers in Amsterdam, Dublin, Frankfurt, London, Hong Kong, and Tokyo. (more…)

httpd: accelerate web page performance with mod_expires

More and more goodies are packaged with apache2, allowing one to perform front-end engineering right out of the box. Here are a tip on using mod_expires to maximize the use of browser cache and accelerate performance for repeat visitors. (more…)

mutt: changing sender mail address on the fly

Had a need today to adjust the sender email address for a notification script. Since the script uses mutt to send the emails, that change was fairly straight-forward. Instead of modifying .muttrc, simply export the EMAIL environmental variable. (more…)