OS Integration

4.Copy over the client.up and client.down files from the OpenVPN contrib directory and make them executable. On Fedora 13, these files are located in the directory /usr/share/doc/openvpn-2.1.1/contrib/pull-resolv-conf:

[root@client]# cd /etc/openvpn/cookbook

[root@client]# cp /usr/share/doc/openvpn-2.1.1/contrib/pull- resolv-conf/client.* .

[root@client]# chmod 755 client.*

5.And finally, start the client:

[root@client]# openvpn --config example10-2-client.conf

After the VPN connection comes up, check the contents of the /etc/resolv.conf file. The first line should contain the DNS server as specified by the OpenVPN server:

nameserver 10.198.0.1

When the VPN connection is terminated, the entry is removed again.

How it works...

The scripts supplied with OpenVPN parse the environment variables foreign_option_* and look for DOMAIN and DNS settings. These settings are then written out to the beginning of the /etc/resolv.conf file. This causes the DNS server and the DOMAIN pushed by the

OpenVPN server to take precedence over the system's DNS and DOMAIN settings.

When the VPN connection is dropped, the same settings are removed from the

/etc/resolv.conf file.

There's more...

Note that when the NetworkManager-openvpn plugin is used, these scripts are not necessary, as the NetworkManager itself updates the /etc/resolv.conf file.

MacOS: using Tunnelblick

This recipe will demonstrate how to set up OpenVPN on a machine running Mac OS X. For Mac OS X, several OpenVPN GUI applications are available. In this recipe, we will show how to use one of them, Tunnelblick (http://code.google.com/p/tunnelblick/).

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Getting ready

We use the following network layout:

I

Set up the client and server certificates using the first recipe from Chapter 2, Client-server IP-only Networks. For this recipe, the server computer was running CentOS 5 Linux and OpenVPN 2.1.1. The client was running Mac OS X "Leopard", Tunnelblick 3.0, and OpenVPN 2.1.1. Keep the configuration file, example10-2-server.conf, from the previous recipe at hand.

How to do it...

1.Launch Tunnelblick if it is not running already.

2.Click on the tunnel icon in the task bar, after which the main Tunnelblick window will come up:

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3.Click on Edit configuration to launch the Text Editor with the default configuration file. Set up the client configuration file as follows:

Note that this is exactly the same configuration as used in the Chapter 2 recipe Server-side routing. Save the configuration and close the Text Editor.

4.When Tunnelblick warns that the configuration file is protected, click on

Unprotect and modify to modify it.

5.Next, start the server:

[root@server]# openvpn --config example10-2-server.conf

6.Then, on the client, click on the Connect button in the main Tunnelblick screen.

Before the OpenVPN connection can be established Tunnelblick pops up a new window. Because the configuration file was modified, Tunnelblick explicitly asks for the Mac Admin password in order to repair the permissions:

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After the Mac Admin password has been entered the OpenVPN connection is established:

If anything goes wrong during the connection phase, the output messages of Tunnelblick and the OpenVPN process can be found in the All Messages screen of the Console utility. The Console utility is normally found in the Utilities folder of the system volume:

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