Friday, October 3, 2014

Installing openvpn 2.3 on CentOS 7

Those of you who run CentOS probably know that the openvpn server package isn't available in the base distribution, nor in the CentOS Plus repositories.  When you peruse the website, they recommend using RepoForge builds (the old DAG repos).  The problem with that is that the repository for CentOS 7 doesn't yet have an openvpn server rpm.  What to do?

It turns out that it's comically simple to build your own RPM, so that's what I'm going to show you.  The instructions come mostly from the openvpn installation documentation.


Go get the latest source tarball from the openvpn downloads page.  At the time of this blog post (Oct 2014), the current version is 2.3.4, so I just used wget to pull it down
 Before I try to build that source code into an RPM, I need to make sure the dependencies are installed and available.  So I used yum to install them:
sudo yum install openssl-devel lzo-devel pam-devel
 Then I follow the instructions for building an RPM (note that the output of this next command creates an rpmbuild folder, so be mindful about where you run this command):
rpmbuild -tb openvpn-2.3.4.tar.gz
After some checking and compilation, there's an rpm in rpmbuild/RPMS/x86_64, and you can install it right from there:
sudo rpm -ivh rpmbuild/RPMS/x86_64/openvpn-2.3.4-1.x86_64.rpm
And now you have an openvpn server installed as a daemon!

Tuesday, December 17, 2013

Configure a FIPS 140-2 Compliant Java Provider on RedHat/CentOS/Fedora

If you're using any form of cryptography in Java, you might be aware of NIST FIPS 140-2, which lays out what you can and cannot use on federal information processing systems.

Oracle documentation, true to form, only gets you 80% of the way there.  Here's their technical notes on FIPS 140 compliance.

So here are the step-by-step instructions for configuring java with a FIPS-compliant Provider (SunPKCS11-NSS).

First, you need to install the libraries if you haven't already.  These are written by Mozilla, and have gone through NIST's Cryptographic Module Validation Program (CMVP).  Luckily, they're available for RedHat/CentOS/Fedora, and can be installed through yum.

sudo yum install nss-pkcs11-devel
 Next, you need to configure your JRE to add the provider.  You do this by editing ${jre.home}/lib/security/ and adding a reference to the SunPKCS11 provider.

On my Fedora 19 box, I have both the OpenJDK and SunJDK installed.  Here are the locations of their JREs on my box.

cd /usr/lib/jvm/java-1.7.0-openjdk-
sudo vim
cd /usr/java/jdk1.7.0_15/jre/lib/security
sudo vim
Be careful that you don't update one and then run your app on the other.  I just configured both and now I can run my apps on either.

Anyway, in the picture below, you'll notice that I've added: ${java.home}/lib/security/nss.cfg

In the same directory, edit (or create if it isn't there) your nss.cfg:
sudo vim nss.cfg
The only change I had to make to this file was to set 'nssLibraryDirectory' to /usr/lib64, which is where your library was installed when you ran 'yum install' earlier.

Now, you may use the SunPKCS11-NSS provider in your Java applications, which is FIPS-compliant.  Here's a tiny app that creates a for creating digital signatures.  It is configured to use the SHA256withRSA algorithm via the SunPKCS11-NSS provider.
 This program just loads the Signature instance - it doesn't do anything with it.  If the program runs without printing a stack trace, then you've successfully configured Java with a FIPS-compliant provider.

You can compile and run your program thus:

Friday, May 18, 2012

Installing MonoDevelop 3 on Ubuntu Oneiric and Mint 12

I really like being able to develop in .NET on linux, and I think that the mono team has come a long way in its efforts to make mono-based applications production-viable.  Sadly, I'm guessing that the majority of mono developers use mac, opensuse, or windows because those are the only platforms that dependably have pre-built binaries and installers.  Since I use Mint (a variant of Ubuntu), I'd really like a simple method for installing a current version of MonoDevelop.

Recently, I needed to install Mint on my new laptop and so I payed close attention to how I installed MonoDevelop and turned it into a script -- which you can now use!  I've tested it on a fresh Mint 12, but it should also work on Ubuntu Oneiric.

The script:

  1. Installs the git client and the dependencies necessary to build MonoDevelop from source.
  2. Downloads the source code for MonoDevelop from github.
  3. Configures the build script to install the stable profile into /usr/local (/usr/local/monodevelop-3.0.1/ will be the full path).  However, you can change the defaults by editing the variables at the top of the script.  
  4. Builds and installs MonoDevelop
  5. Creates a script in $INSTALL_PREFIX/bin that simply calls the real monodevelop script.  This is because you can't just create a symbolic link.  This step has a bad smell to it - if you know a better way to do what I'm trying to do, please leave a comment.
  6. Adds two environment variables into your ~/.bashrc file
You should also know that it has a dependency on gnome-sharp2, so I don't know what to do if you're not using something based on gnome.  If you want to save some hard drive space after the install, you can delete the MonoDevelop source code directory that gets downloaded.

You can download it here:

Don't forget to run it with sudo!

Thursday, April 12, 2012

Installing CouchDB 1.2 on CentOS 6

CouchDB has a really great idea behind it.  Whether or not CouchDB delivers on it, I've been wanting to discover for a while.  Only way to do that is kick the tires, so I started the process of figuring out how to install it.

First disappointment is discovering a general lack of documentation.  But my first appreciation is how simple it is once you figure out what needs to be done.

CouchDB runs on erlang, so you need to install erlang from the EPEL repository.  In order to use that repository on CentOS 6, run the following command:
sudo rpm -Uvh
Now you can install erlang:
sudo yum install erlang
That will bring with it a number of dependencies, such as wxWidgets.  With erlang now available, it's time to download the CouchDB source code from here. As of this writing, the latest release is 1.2.0, although 1.3 is in alpha in master.  I'm electing to use the stable release.

Now that you have the source, unpack, configure, build, and install it.
tar zxvf apache-couchdb-1.2.0.tar.gz
./configure --with-erlang=/usr/lib64/erlang/usr/include
sudo make install
If you want to be able to reach the database from other computers on the network, you'll want to edit the configuration file:
sudo emacs /usr/local/etc/couchdb/local.ini
Under the [httpd] section, uncomment the bind_address setting and change the value to if you want couchdb to listen on all available interfaces.

Also, since you've installed from source instead of from a package, let's configure CouchDB to run as a daemon that starts up when we boot.
sudo ln -s /usr/local/etc/rc.d/couchdb /etc/init.d/couchdb
sudo chkconfig --add couchdb
sudo chkconfig --level 345 couchdb on
Finally, let's create a couchdb service account that will run CouchDB, and then fix some file permissions to give the service account access to what it needs at runtime.
sudo adduser -r --home /usr/local/var/lib/couchdb -M --shell /bin/bash --comment "CouchDB Administrator" couchdb
sudo chown -R couchdb: /usr/local/var/lib/couchdb /usr/local/var/log/couchdb /usr/local/var/run/couchdb /usr/local/etc/couchdb
That's it!  You've installed CouchDB on CentOS 6!  Start the database with:
sudo service couchdb start
 You should now be able to get the welcome result by browsing to http://localhost:5984/ (unless, of course, you just installed it on a remote machine).

Time to Relax!

Tuesday, January 10, 2012

Invalid provider type specified when accessing X509Certificate2.PrivateKey

Today, I was attempting to digitally sign a byte array with my private key so that I could produce an event on the event bus and a consumer could ensure that the message came from me and was not modified while in transit.

public byte[] SignData(byte[] data)
  X509Store certStore = new X509Store(StoreName.My, StoreLocation.CurrentUser);

  // the DN I get is CN=name,CN=Users,DC=example,DC=com
  // but the DN on the cert has spaces after each comma
  string spacedDN = UserPrincipal.Current.DistinguishedName.Replace(",", ", ");

  X509Certificate2 cert = certStore.Certificates

  if (null == cert) { // handle no cert }

  RSACryptoServiceProvider rsaProvider = cert.PrivateKey as RSACryptoServiceProvider;
  return rsaProvider.SignData(data, new SHA1CryptoServiceProvider());

When I run this as myself, I get the following exception:  
System.Security.Cryptography.CryptographicException: Invalid provider type specified.
... the stack trace boils down to ...
This wasn't a terribly enlightening exception message, so I asked google and found this link and this link.  It turns out that by using the newest Certificate Templates (version 3), I am using Microsoft's new Key Storage Provider (KSP), and not the Cryptographic Storage Provider (CSP) that we normally expect.  Windows Server 2008-based certificate templates use the KSP as part of what M$ calls Cryptography Next Generation (CNG).  While .NET 4 does provide managed implementations of the CNG stuff, they are not FIPS-compliant, which is a deal-breaker for me.

So what is a FIPS-constrained boy to do?  Well, I had to delete my auto-enrollment templates that were Windows Server 2008-based and replace them with Windows Server 2003-based templates.  When you duplicate a template using the Certificate Templates MMC snap-in, it will ask you to choose between 2008-based and 2003-based.  Select 2003-based and then revoke any certs you may have issued based on the 2008-based templates.  Let auto-enrollment take its course and then you'll find that you no longer get the invalid provider exception when you access your private key.

Tuesday, December 27, 2011

Establishing a SSL connection to RabbitMQ using the .NET client

First, I'm making the assumption that you've read, re-read, and followed the SSL tutorial on rabbitmq's website.  If you haven't done everything that it's instructed you to do (including adding your certificates to the Windows Certificate Store using certmgr), none of this code is going to work for you.  If you have, this code should "Just Work™".

Here's the complete code file that works for me.  You will (obviously) need to change the names of the servers, and the thumbprint of your certificate.

Note that this code only uses your client and server's certificates to establish a secure connection.  You are still logging in as guest.  I will show you how to use your client certificate to authenticate yourself below.
using System;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
using System.Text;

using RabbitMQ.Client;
using RabbitMQ.Util;

namespace RabbitSslTest
    class Program
        static void Main(string[] args)
            Program p = new Program();

            Console.WriteLine("Press <ENTER> to exit.");

        public void Start()
                // we use the rabbit connection factory, just like normal
                ConnectionFactory cf = new ConnectionFactory();

                // set the hostname and the port
                cf.HostName = "rabbitmq-server";
                cf.Port = AmqpTcpEndpoint.DefaultAmqpSslPort;

                // I've imported my certificate into my certificate store
                // (the Personal/Certificates folder in the certmgr mmc snap-in)
                // Let's open that store right now.
                X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);

                // and find my certificate by its thumbprint.
                X509Certificate cert = store.Certificates
                        "6d 36 c0 f9 c2 f8 72 05 d1 01 6c 54 e1 91 bb 2d 66 7b ac 94",

                // now, let's set the connection factory's ssl-specific settings
                // NOTE: it's absolutely required that what you set as Ssl.ServerName be
                //       what's on your rabbitmq server's certificate (its CN - common name)
                cf.Ssl.Certs = new X509CertificateCollection(new X509Certificate[] { cert });
                cf.Ssl.ServerName = "rabbitmq-server";
                cf.Ssl.Enabled = true;

                // we're ready to create an SSL connection to the rabbitmq server
                using (IConnection conn = cf.CreateConnection())
                    using (IModel channel = conn.CreateModel())
                        channel.QueueDeclare("rabbitmq-dotnet-test", false, false, false, null);
                        // create some basic properties for the message we're going to send
                        IBasicProperties props = channel.CreateBasicProperties();
                        props.ContentEncoding = "utf-8";
                        props.MessageId = Guid.NewGuid().ToString();

                        // publish a hello world message
                        channel.BasicPublish("", "rabbitmq-dotnet-test", props, Encoding.UTF8.GetBytes("Hello, World"));

                        // and go get it
                        BasicGetResult result = channel.BasicGet("rabbitmq-dotnet-test", true);

                        if (null == result)
                            Console.WriteLine("No message received.");
                            Console.WriteLine("-----==<([ Received ])>==-----");
                            DebugUtil.DumpProperties(result, Console.Out, 0);

            catch (Exception ex)
 And the output:

Using your certificate to authenticate
If you want to authenticate yourself with your certificate as well, you need to change the code and your rabbitmq server's configuration.

First, update your rabbitmq server's configuration.  If you don't know where to look for that, read this page.  Here's what mine looks like:
  {rabbit, [
     {ssl_listeners, [5671]},
     {ssl_options, [{cacertfile,"C:/Path/To/Your/cacert.pem"},
The thing to note there is the addition of {auth_mechanisms,['EXTERNAL']}.  Don't forget to stop your service, re-install it, and start it after making these changes.
rabbitmq-service.bat stop
rabbitmq-service.bat install
rabbitmq-service.bat start
Next, let's update our client code just a tad by setting the connection factory's auth mechanisms.

// we use the rabbit connection factory, just like normal ConnectionFactory cf = new ConnectionFactory();

// set the hostname and the port
cf.HostName = "rabbitmq-server";
cf.Port = AmqpTcpEndpoint.DefaultAmqpSslPort;
cf.AuthMechanisms = new AuthMechanismFactory[] { new ExternalMechanismFactory() };

// I've imported my certificate into my certificate store
// (the Personal/Certificates folder in the certmgr mmc snap-in)
// Let's open that store right now.
X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
The other change I made was to insert a Console.ReadLine() just before all of my using () statements cause everything to close down.  By doing this, I can view the RabbitMQ management web app to ensure that I'm authenticating using my certificate.

Wednesday, December 21, 2011

Windows does not always honor DNS order

I was having a problem where some internal server names would become unresolvable after being resolvable.  After becoming tired of flushing the dns resolver cache, I finally opened wireshark to see what was going on.

To my surprise, windows was using my secondary DNS ( instead of my primary, internal DNS!  After some searching, I finally found this knowledge base article.
This behavior occurs because the Windows XP DNS Client service (Dnscache) follows a certain algorithm when it decides the order in which it uses the DNS servers configured in the TCP/IP properties. If the DNS server list is reprioritized, the Windows XP DNS Client service resets the server priority at periodic intervals. By default, the server priorities are reset every 15 minutes.
 Luckily, the workaround in that same article fixes the issues I was having.
To work around this behavior, modify the registry so that the DNS server that is configured first is tried first on each query. Follow these steps, and then quit Registry Editor:
  1. Click Start, click Run, type regedit, and then click OK.
  2. Locate and then click the following key in the registry:
  3. On the Edit menu, point to New, and then click REG_DWORD.
  4. Type ServerPriorityTimeLimit, and then press ENTER.
  5. On the Edit menu, click Modify.
  6. Type 0, and then click OK.
When you set ServerPriorityTimeLimit to 0 (zero), the server priorities are reset before the DNS Client service decides which DNS server to use. You must restart Windows XP for these changes to take affect. Any other value used in this field will cause the default behavior.
Even though this article is for Windows XP, this worked for me on Windows 7.