Blog
-- Thoughts on data analysis, software
development and innovation management. Comments are welcome
Post 5
Getting my VPN to work, at length
05-Dec-2008
Getting a Virtual Private Network (VPN) to work under GNU/Linux can
be a pain. I have had, like many other people, a lot of trouble to set it
right. Some time ago I did have my attempts, I
eventually got to establish the
connection but the traffic wouldn't route with success.
A day ago Dr. Vilella told me he already had a VPN working with the
Ubuntu
network-manager-pptp. He had even set it in Fedora with
pptpconfig
.
With the evidence that a GNU/Linux VPN was indeed possible, I put my hands
to work until
I got to understand it and succeed in establishing the tunnel.
The protocol, PPTP, a piece of Emmental cheese. The OS, Debian, the anvil
of stable GNU/Linux distros. The manual, an article from nixCraft called
Linux configure point to point tunneling PPTP VPN client for Microsoft PPTP vpn server.
After following the instructions of the article, my VPN did set, the
P-t-P private address did appear
in the kernel routing table, but the default
gateway didn't change, so I was unable to send traffic trough the VPN.
Trying to set it manually was useless because once the original
default gateway was removed, the connection was lost.
In order to avoid that problem,
the following steps led me to success:
-
Add a static host-route to the VPN server with the original default GW:
route add -host vpn_server_address gw original_default_GW dev eth#
-
Launch the pppd client:
pppd call vpn_tunnel_connection_name
-
Delete the original default GW:
route del default
-
Add the P-t-P private address assigned by the VPN server as the new default GW:
route add default gw ptp_address
By following these instructions, when the original default gateway is
removed, the connection with the VPN server is not lost because of the
static host-route.
Now, with a functional GNU/Linux VPN to the
university I can keep on my development and
research tasks as if I was materially in my everyday workplace.
VNC and rdesktop clients to a MSWindows box for a VPN
tunnel is history.
|