In the Internet age we live in, it’s not uncommon for web servers to be hit with Unintentional, not so Distributed, Denial of Service (DoS) Attacks. The attacks itself is intentional, but it’s not trying to bring down the server. It’s just some stupid ‘bot running a probe as fast as it can and, as a side effect, bogging down your server.
Bots are evil, but at least smart bots rate limit themselves to keep off the radar.
The typical stupid bot is running a password probe against an admin login. If you run any WordPress sites, you see this. All. The. Time. There are many good options to prevent these attacks, including renaming well known URLs, IP filtering, and automatic IP banning software, like Fail2ban.
However, sometime you just need to make the attack go away now. For that, I have a couple of Bash functions/tcsh alias.
I often find myself needing to download files to my local box via SCP. Which means entering the hostname, the path, and the filename in to my terminal window. However, I’m really lazy, if I can’t auto complete it or cut and paste it, I’m not happy. Enter this simple Bash function:
I’m lazy and I’m always looking for ways to avoid any unneeded typing. Here’s a little OpenSSH configuration tip that can save you up to 16 characters (if you have crazy long usernames).
In most cases, if you enter 0 for an IP address it will expand to 0.0.0.0. Likewise, 127.1 will expand to 127.0.0.1. Why? Magic.
But really, why do these shortcuts exist and how do they work? It can’t be as simple as adding zeros, if it was 127.1 would more logically expand to 127.1.0.0.
Sometimes an AJAX request on a page you’re developing needs to hit a server on a different domain. Web browsers’ Same-Origin Policy means (among other things) that other domains called from AJAX need to be whitelisted using the Access-Control-Allow-Origin header.
Fortunately, there’s an easier way, temporarily disable same-origin policy.
As part of the work Indra did for Stand Up To Cancer’s telethon, I need to make use of Convio/blackbaud’s Luminate Online Server APIs. Luminate Online is a widely used fundraising platform and relationship manager for non-profits.
I’ve turned that development work into open source in the form of gem providing Ruby bindings to the APIs.
I have only implemented a handful of endpoints, Luminate Online doesn’t have any kind of test mode or sandbox, any testing has to be done with live data. However, I’ve used a meta programming approach making it easy to quickly add additional endpoints.
All of the endpoints I have implemented have been used in anger.
The details are in the repo: https://github.com/spikex/luminate
Yesterday, I was involved in a fire drill around the launch of a new Rails site on a very tight time frame. The site worked fine in development/staging, but the index was taking upwards of 10 seconds to render in production.
Because it worked outside of production we leapt to the conclusion it was related to the hosting infrastructure. We checked Apache, Passenger, server load, network configuration, and so on. Nothing.
Finally, I thought to check
log/production.log, and there is was:
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We quickly tracked it down some image processing that wasn’t being cached. It didn’t show outside of production because the image assets were different. I won’t bore you with the details.
However, I will
bore enlighten you as to my point. When debugging
a problem, start with the simple things. The Rails logs aren’t very
detailed, but they provide more than enough information to quickly
drill down to problems in your code.
If you try to build Ruby 1.8.7 with RVM you will see:
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The work-around, is to install GCC, either with
or from Ports:
Once you have gcc you can install 1.8.7 with:
This should work with older versions of Ruby 1.9 as well.
What on earth would you want to install 1.8.7? Two words: Legacy Apps…
Previously, Strongbox, my gem for using Public Key Encryption with ActiveRecord, allowed only one key pair for encrypting all of the records for a given ActiveRecord model. I’ve had a number of requests to make it possible to dynamically choose the keys on a per record basic and version 0.6.0 adds this feature.
The values of
:key_pair can be in one of the following formats:
A string containing path to a file. This is the default interpretation of a string.
A string contanting a key in PEM format, needs to match this the regex
/^-+BEGIN .* KEY-+$/
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A symbol naming a method to call. Can return any of the other valid key formats.
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An instance of
OpenSSL::PKey::RSA. Must be unlocked to be used as the private key.
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Using this, you can automatically create per record public keys:
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Important Caveat -
Currently, Strongbox encrypts the attribute as soon as it’s assigned (this will change in version 1.0). The means that the public key must be available before the attribute is assigned, hence the use of
after_initialize to generate the key pair. Even so, this will fail if you do something like:
because the attributes are set before
after_initialize is called.
Instead, use something like:
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Version 1.0 will allow you to control when the encryption occurs, making this less of an issue.
As always, I like building Emacs for my Mac from source. It lets me live on the cutting edge and have tigher control of the version I’m running. If building software from source isn’t your thing then skip the rest of this article and consider installing Emacs using Homebrew, MacPorts, or Fink
I’ve written about building Emacs in the past, but OS X Lion brings a few complexities to the process.