Open Source Geek

Ive been a cloud *client* for quite some time, firstly with Gmail and Google docs, later with Dropbox and Amazons S3 storage (via Jungledisk). I’m also a fan of virtualisation and, while listening to a recent FLOSS Weekly netcast with Ian Pratt, I found out that Amazons EC2 (Elastic Compute Cloud) is indeed based on Xen. Now I had an interesting chat with one of the guys from Citrix recently also, I decided it was time I took a look at Amazons offering.

EC2 offers you the ability to “stand up” multiple servers almost instantly, configure and run them and only ever pay for the number of hours they are up. A server instance starts at $0.10 an hour – this is for their “small Linux instance”, which is 1.7gb ram and 350gb disk space. They also offer Windows instances which are slightly more, but still amazingly low priced. This makes it extremely cost effective to use for large proof of concept work or for full time production. Anyway, let me walk you through my first steps in/on Amazons cloud.

First of all you have to have an Amazon account, as I already had one all I needed to do was to “sign up” for the EC2 service (remember you pay for what you use in server/hours). Two clicks later and Im ready to go.

In my eagerness to get started I overlooked the “Getting Started” video on the front page and decided to see how for I could get without reading the documentation. If you want the short answer – I had my first box up and running in less than 5 minutes. For the more detailed version read on,

There are a couple of steps to complete before you get you box up and running and the interface holds your hand nicely through these. Im impressed with the level of security that is setup right out of the box. The two steps you need to do (apart from choosing your instance) are both security related. Firstly you need to select or create the security group – in other words the firewall settings. There are suggested entries there already and customising it is very simple.

Secondly you will need to generate a keypair that you will need to administer the boxes. Again the wizard walks you through this step also, Once those two steps are done and you have chosen your instance type, you click on create and after a minute or so you can see your first instance change its status to starting.

Cool, lets see the console then.

The first instance I chose to create was a Fedora box, so when I hit the “Console” button I was provided with details on how to connect to the instance. For now, you connect to the DNS name that Amazon give you, which maps to a local IP address within Amazons cloud. You can also rent “Elastic IP” addresses for $0.01 per hour, I decided the funky DNS name and private IP was fine for my testing. So I SSH to the DNS name, referencing the file that contains your keypair. The provide the exact syntax that you need to use but its pretty straightforward. You are not prompted for a password as you are using, the more secure, keypairs. And thats it – you have a bash console your box.

I yum installed an Apache server and hit the page in my browser and there was the default webpage. I then went on to setup a WordPress install jas i would on a hosted server. Everything went to plan

As my first hour approached its end I shut down the instance and went out. Upon my return I wanted to try a Windows host. Interestingly the previous instance had disappeared. It seems that if you shutdown an instance, for a certain period of time, the diskspace is reclaimed. If you want to keep instances around when they are shutdown you can do this by using Amazons EBS (Elastic Block Store) which is $0.10 per gb per month.

Anyway, as I mentioned above, I decided to try a Windows box next. I selected the Server 2003 and SQL Server 2005 instance. This time the firewall settings suggested were as follows

• Remote Desktop (3389)
• HTTP (80)
• SQL Monitor (1434)

I accepted the defaults but if I was going to use it “in production” I would close the SQL port. I clicked the button to fire up the instance and a minute or two later it changed its status to “running”. Hitting the console button this time brings up a box explaining how to connect to the server, namely via RDP. Again security is there right out of the box because the local Administrator password is randomly set and then encrypted in the instances log file. To get to this password you have to right click on the instance in Amazons control panel and select decrypt password. You are prompted to paste in your key to a dialog box and a few seconds later your password is displayed.

Pointing your RDP client to the DNS name of the instance and using these credentials gets you logged onto your server – its as easy as that. This would make testing things like large scale Exchange setups, that involve many servers talking to each other, really easy and you wouldn’t have to stump up for the hardware required to do this in your own lab.

This (EC2) is just one of the services that Amazon offer. I’ve been very impressed with my first steps in the cloud, things couldn’t have been any easier to get up and running and I’m pleased to see that security has been part of the core design. When you consider that the underlying technology is Open source then I think its something we (the Open Source community) can be proud of.

OSG

Update:
There is talk on the net about Amazon open sourcing its cloud tools – this would great news and very beneficial for The Cloud as a whole. So nice to see people aren’t trying to lock down or lock you into their offerings – lets hope it turns out to be true

More Screenies

Edit:
Sorry about the lost screenshots, this was due to a major incident at my previous hosting provider. At least I had the databases backed up :-/

Once you start running/administering your own server, live on the internet, you really need to think about securing access to it. In this post, Im going to look at the different ways that you can achieve this and the pros and cons of each of these

Firstly lets think about what it is that we are trying to prevent and what we it is that we are not trying to prevent. For this discussion I’m going to assume the server that we are running is a simple webserver hosting a blog. So therefore we want the world to be able to view our blog but not to be able to log on to the server and perfrom admin tasks.

We wil assume that the webserver listens on the standard web ports of 80 & 443, that it connects to a mysql server on the same box (running on 3306) and the we administer the box via SSH, again on the standard port – port 22.

Firstly lets take care of the low hanging fruit. MySQL will, by default, bind to the servers live IP address and so expose port 3306 to the world. (by default it wont allow remote logins but its still a port that is exposed that we dont need to have exposed). Opening the config file for MySQL (/etc/my.conf) we can simply use this line “bind-address=127.0.0.1″ and restart the service to make it bind to the loopback instead. (We will assume that you did this before you setup your blog software and so the blog software was configured to use 127.0.0.1 as well)

Good, so thats one port now taken care of. This just leaves the web ports (80 & 443) and ssh open to the world (port 22).

The next thing we need to decide is just exactly how secure we want to be – remember the is an inverse relationship between ease of use and great security; its always a trade off.

Relaxed Approach
We may decide that this is only our blog, that we have a regular off site backup of the database and so we arent really too concerned about security. If this is the case we could probably stop right here, making sure that we

• Use a strong root password
• keep the webserver up to date with latest patches
• keep the blog software up to date with the latest patches

Pros – very little work to setup. Can admin from anywhere, doesnt require additional software (ssh keys)
Cons – you are exposing port 22 to the world and could potentialy be at risk to a zeroday attack or someone just guessing/bruteforcing your password

Restricting Access
We may decide that doing a little more to secure remote access is worthy investment, but we dont want to go crazy. Here are some of the things we could do

Limited range of IPs allowed – Use a firewall (IPTables typically) to only allow a few IP addresses access to port 22. This assumes you will always connect from one of these IPs and never need to admin the box from anywhere else
Automated, proactive, blocking of rouge IPs – If we need to make sure that we can admin the box from anywhere (lets say we travel a lot and dont wont to limit access down to a few IPs) we could use tools that watch for, and react to, brute force password atempts.

The two programs I would recommend here are Fail2ban which looks at your logs and if it sees a certain number of failed password attempts will add a firewall rule to block the source IP and DenyHosts which does a similar job but instead of adding a firewall rule, the source IP is added to /etc/hosts.deny. The nice thing about Deny Hosts is that it gives you the ability to sync your entries with other peoples. Lets face it, if someone is brute forcing your box, they are almost certainly doing it to soemone elses as well. There is nothing stopping you using both Fail2ban and DenyHosts at the same time for a belt and braces approach.

Pros – this is much more secure, you have heavily restricted the number of users pounding on your box, while allowing yourself the ability to admin the box
Cons – takes a little more work to setup and you could potentially lock your own IP address out if you are not careful

Higher Security Approach
So we have decided that security of our box is very important and so we are going to go put extra affort into securing it.

Limit to SSH Keys only – we can disable the ability to logon using a username and password full stop, limiting it to SSH Keys only. This means that even though the port may be open to the world, its imune to password brute forcing. You could combine this with the “Restricting Access” approach if you want to go the extra step.

Pros – you have elimated the attackers ability to bruteforce/guess your password, drastically reducing your exposure to a breach
Cons – requires that you have with you the coresponding SSH key when you need to access your server

Paranoid Approach
No matter what, you just arent comfortable with the admin port being visable, you want to retain the ability to remotle admin the box but you dont even want people to be able to see or connect to the admin port. Sound impossible? Not so, we can use one of these two methods to make this happen.

First off is Port Knocking. This means that port 22 is totally firewalled off until the box receives a certain sequence of packets to a predefined set of ports – so maybe the sequence is tcp/6880, udp/3399, tcp/8881 – if the box receives these packets in this sequence then it will open port 22 to the source address for a limited time – at which point you connect.

The downside of this for the ultra paranoid is that if someone sniffs the network at the same time that you send the sequence, then they know you sequence and could replay them and enable visibility to port 22 for themselves. This is where the second approach comes in – SPA

SPA or single pack authentication evolved from port knocking. It addresses the weaknesses (capture and replay) and adds some functionality. In a nutshell you send a single packet to your server with an encrypted payload that describes what you want to do. So for example you may say that you want to enable port 22 on server x and port 2222 on server y – this request is encrypted and sent to the server. The server receives the SPA packet and, if you have used the correct password to encrypt it, decrypts the contents and acts on them. It is imune to a replay attack as the the contents of the packet have a timestamp included in the encrypted payload. I really like this approach and use it to gain access to my home network.

The software I use to do this is called FWKnop and more information can be found here

Pros – you are as secure as is humanly possible, it doesnt get more secure than this unless you disconnect it from the internet and bury it in a bunker
Cons – you need to have the client software installed on the machine you want to admin from, in order to send the SPA packet

Feedback
if you feel I have missed anyting off, made mistakes or just want to let me know about your methods of securing remote access – please use the comments box to give me your feedback

OSG

Next we should probably think about installing a HIDS but I will save that for a future post

Disk imaging is used extensively within the IT departments of most companies. This enables them to quickly build desktops and laptops, to a repeatable standard and backup critical devices in order to quickly recover from a hard disk failure. In the past this has required some fairly expensive and proprietary software. These images are generally stored on a server but engineers can, and regularly do, carry a handful of them around with them.

The individual components required to do this with Open Source software do exist but until recently no-one seems to have tied them together with a nice, web based, front end. Enter FOG – a free open-source computer cloning system, which does exactly that. FOG is a Linux based server, that lets you backup and restore disk images for desktops/laptops and servers without the need to even carry a boot floppy/CD – as it uses PXE to boot from the network.

If setting this up sounds complicated, they do provide a VMWare virtual appliance for you to download use to do your initial testing – however, due to the large amounts of storage and IO demands, the VMWare appliance isn’t recommended for large scale production environments.

My initial tests are very encouraging and so if disk imaging is something that you are interested in, I wholeheartedly recommend checking this project out  – kudos to Chuck Syperski and Jian Zhang for creating this.

OSG