Wednesday, September 19, 2018

Using a Free AWS box as Web Proxy Box

Throughout the year, there is always a need for a remote SSH box. SSH is a reasonable way to do management of external/remote computers (command-line, bash, etc.), run DNS/network lookups from the Internet DNS servers and to even test web content without the interference of internal spam filters. Taking on this project has helped me learn about Amazon Web Services(AWS) and some automation functionality capable in the environment.

Configure AWS SSH Proxy box

NimrodFlores does a wonderful job explaining his process for spinning up a box in AWS, and configuring the putty client to connect. I had 3 issues with his final answer though.

  1. The post suggests using changing the default proxy settings for your browser. This is a less than ideal solution for me as I must use the similar browser for accessing the corporate resources. Using a proxy box would make this impossible. I've found that the Chrome extension "FoxyProxy" is free and allows me to one-click turn-on and turn-off the proxy usage. 
  2. The box is never shut down. There is a hypothetical point when I would incur charges due to the amount of time the server is running. I really want the box to start on weekday mornings and stop when I am not using it. 
  3. By stopping the instance each night, Amazon puts a new IP address each time. This requires that you update the SSH session each time. My first idea was to attach an elastic IP address to this instance, but that generated a few cents/day charges for the 'static' address. I am now at $0.86 for the first 2 weeks of the month.I believe by getting rid of the EIP that out, I can stop that recurring charge. 

I posted these in his comments section, but my post was never approved and eventually deleted. /shrug

Part 1: Stopping and Starting the instance magically.

Starting the server: These instructions by Amazon are good. You can configure LAMBDA scripts to stop and start your instance on scheduled CRON events. The hardest thing about configuring the script was adjusting for GMT to local time. I setup both scripts but decided to use a different stop process.

Stopping the server: Instead of a cron job, I decided to use a CloudWatch alarm to stop an instance when the CPU utilization dropped down below a certain threshold. These AWS instructions are useful. The biggest trick came in finding the baseline CPU utilization between actively browsing the web of one user, vs idle chatter between my workstation and the server when I left the browser open. I currently stop the instance when the CPU Utilization drops below 0.117 for 2 hours.

Part 2 - Dynamically updating IP address

The instructions from NimrodFlores use the dynamically generated IP address from the EC2 instance page. While this is easy, it requires logging into the AWS portal each time I want to capture this, then update the putty session. (I only want to click on my shortcut on my toolbar and auto-connect to the proxy.) To work around this, I plan to use a dynamic DNS entry instead of the IP address in the putty session. 

I use ZoneEdit for a couple reasons. First off their free for the two websites I host there. Plus they offered dynamic dns options for when I wanted to host this blog on my home PC over a dial-up DSL line (pre-blogger)

For the proxy box, I decided to spin up a DYN record for the new hostname. Enable and take note of the "DYN Authentication Token" field at the bottom. Use this as the password alternative, not your ZoneEdit password.

I tried their both of their options on the automated dynamic DNS update, then found a post in their forum where they no longer support the ez-ipupdate option. Learned that AFTER I installed all the options required to compile the solution. The Javascript option is 'interesting' if you have a browser running on the Ubuntu server. I don't want to incur any additional costs, so smaller is better. Luckily I found DDClient.

Dynamic DNS - DDClient
Here is a wonderful set of instructions posted on linhost.  There are a few screens that don't match the wizard, but it steps through the install and basic configuration options. After the wizard is complete, you need to modify the configuration file. (don't do like me and reboot your server thinking it's complete after first installed.

This post has some other tweaks specifically regards to zoneedit you could add. No one responded to the question, but I believe that is about the time ZoneEdit was purchased by another provider.

Since the first of the month, I have racked up less than a $1 in charges on my AWS server. Of this, 80% was incurred during the time the EIP was running. Besides the 80 cents, I am being charged roughly a 1/3 of  1 cent for each 'configuration item'. At last check, I have 39 configuration items (i.e. $0.12). I've gone through and deleted a number of those items, but I don't think I can shrink it much more than $0.10.

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