depending on your kernel you might need to
modprobe tun
if it turns out you do not have such module available - you'll need to upgrade / recompile your kernel [ it's good idea to do anyway 2.6.9 is quite ancient and probably vulnerable ].
the easiest way is by taking appropriate package from the distribution you are using.
If you post your server.conf it will greatly assist others in helping.
Firstly, the errors you are getting are specifically about the ROUTES being pushed, not necessarily the IP assignment. The logs show that it's trying to get an IP, so I assume that's configured on the server, but it doesn't look like routes are. I'll go over both items...
IP Assignment:
To define what range of IP addresses you get from the OpenVPN server, you set it at the "server" item in your server.conf and, in my working config, defined the topology as "subnet":
Example:
topology subnet
server 10.10.18.0 255.255.255.0
In the above example, the Subnet for clients will be 10.10.18.0/24
It looks like, from your log you are pushing a subnet (192.168.5.6/255.255.248.0) so that may already be configured properly.
Routes:
The errors are specifically complaining about the routes.
Your log shows 0 out of 0 total routes were successful, so it sounds like it doesn't even have any routes to push too.
0/0 succeeded
In the server config file you utilize the push item to push out routes to the clients. Ensure you have the routes defined in your server.conf.
Here is an example:
push "route 10.10.2.0 255.255.255.0"
push "route 10.10.3.0 255.255.255.0"
If you provided your server config it would really help out.
Summary:
Ensure your server.conf is configured to assign addresses properly, and it's configured to push your desired routes.
Best Answer
Enable TUN/TAP device driver support in kernel.
It will work!