Jeremy Durham

Although my DNS-321 is last year’s model, having been superseded by the awesome DNS-320, I decided last night that I’d love to get OpenVPN running on it and set up a VPN that would give me access to my shared directories and home computer from the office.

OpenVPN requires liblzo, which is available for fun_plug, so I grabbed that and installed it:

wget http://www.inreto.de/dns323/fun-plug/0.5/extra-packages/libs/lzo-2.03-1.tgz

funpkg -i lzo-2.03-1.tgz

There is also an OpenVPN package, but it’s built for the DNS-323, so I installed it:

wget http://www.condor-edv.com/~rubber/Download/openvpn_2_1_2-DNS323.tgz

funpkg -i openvpn_2_1_2-DNS323.tgz

After installing, attempting to start gave me “invalid module format”, with dmesg telling me that the tun module included in the package was compiled for a different kernel than the stock kernel on the DNS-321.

A bit of Googling told me that no one (I could find) had provided a tun module for the DNS-321, so I set out to create one. Having been a Mac convert from Linux for the last 4 or 5 years, I haven’t built a kernel in quite a while, but it proved to be like riding a bike. I won’t get into the dirty details but you need version 2.6.22.7 of the kernel, the .config from the DNS-321 kernel, and an hour or so to kill. “make config” still works and after answering the right questions I was able to “make modules”, install the tun module and configure my VPN.

Although the DNS-321 is not as popular as it once was, I hope this helps someone else (or future me). Here is a copy of the tun.ko built for DNS-321 firmware 1.03: tun.ko