WWW posts page 8

Fallback webfont and emoji

in

Recently I found that browsers will download a fallback webfont (@font-face) to try to find an emoji or other missing character. I was looking at the perf characteristics of my site when I noticed that the browser was downloading a webfont that wasn’t being used at all. After some digging, I found that the browser was going down through the full font stack to try to find an emoji I had added to that page, downloading the webfont on the way.

This is probably not a common setup, but I have a webfont in my font stack down stack from some similar common system fonts, as a fallback just in case. It uses a nice system font unless it can’t find it, in which case it uses the webfont, unless it can’t use that, in which case it uses a less desirable system font or the generic font class.

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Fighting form spam

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Cogneato has dozens of sites with openly submittable forms on them, and they have no doubt all had some level of problems with spam submissions. Bots, and perhaps people, like to share their links or services, try to hack sites, or whatever other nefarious or annoying purposes they may have through forms, which require some sort of server side processing, and will possibly result in human processing as well, such as with sent emails, database data, or comments on a website.

Spammers have gotten more sophisticated over time, and over the last year or two, have really started to hit Cogneato’s sites hard and get past the protections we had in place. We’ve had to add protections on forms that didn’t have them before, and use more techniques to attempt to detect spam. We’ve recently added a set of checks of the submitted form data and the submitter IP address that produces a score of “spaminess” that we can then use to block the submission if the score is above a threshold. That score script is the primary purpose of this post, but I will cover the other techniques we use as well.

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PHP-FPM / Apache caching symlinks

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At Cogneato, we use symlinks to point the web server to different versions of our software for websites. Sometimes, especially on our Ubuntu server, which uses PHP-FPM to serve PHP files through Apache, I was noticing problems caused by scripts being loaded from the previous symlink destination when I changed to the new one. There seems to be some sort of caching going on. The solution was to restart PHP-FPM and Apache after switching the symlinks. On Ubuntu, this looks like:

ln -s /path/to/new-version /path/to/software-link \
&& sudo service php7.2-fpm restart \
&& sudo service apache2 graceful

where the 7.2 is the version of PHP being used. Haven’t noticed the problem since.

Looking at Apache logs with command line tools

in

In my web development career, I have countless times needed to look at Apache logs to figure out or find out about problems with sites, monitor activity, or for various other purposes. I’ve used command line tools to help with this, often looking for strings and counting occurrences. Since I recently needed to create a command string to count unique IP’s connected to a given string in the logs, I thought I’d post about it and a few related useful commands.

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Custom logic for unattended upgrades reboot

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The Ubuntu / Debian unattended-upgrades package has an option to automatically reboot as needed when it upgrades packages. It will do this without user input, at a chosen time. However, it doesn’t allow for any conditions beyond need and time. I found a need for more nuance recently, so I had to disable the built-in functionality and set up my own script on a cron job.

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Automatically deal with conf changes using unattended-upgrades

in

For Ubuntu servers, I use the unattended-upgrades package to automate keeping the system and packages up to date. I recently noticed some of Cogneato’s servers showing packages needing to be updated for multiple days. When I looked in unattended-upgrades.log (in folder /var/log/unattended-upgrades/), I found the message “WARNING Package something has conffile prompt and needs to be upgraded manually”. Basically, there was a change to a configuration file and it didn’t know how to handle it.

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