VPNC with Linux
Warning: this is old information and may not work anymore
VPNC is an alternate VPN-Client for the Cisco IPsec servers. In Debian it's available since 3.1 (Sarge) and it should be available in most other modern Linux distributions.
See the end of this HowTo for instructions about manual installation on older Linux distributions such as Debian 3.0 Woody.
Debian and Ubuntu
In recent version of Ubuntu the package "vpnc" is part of the default desktop installation. Choose the menu Applications->Add/Remove... and search for "vpnc". If it is not already installed you can do that directly there.
Alternatively you can install the package "vpnc" as root (or with "sudo" prepended) from the command line
apt-get install vpnc
Using the ISG EE Ubuntu AddOns
For all Debian based dsitrbutions (using the .deb package format) such as Debian and Ubuntu (maybe also Xandros), you can use the isgee-vpnc-ethz package which includes a ready-to-use configuration as well as some helpful helper scripts targeted on usage with the ETHZ VPN.
The package's configuration connects to the ETH public VPZ by default. If you want to connect to your own VPZ, you may need to modify the configuration file
/etc/vpnc/ethz.conf or create a new configuration file. See manual configuration below.
On Ubuntu you can easily install it adding the ISG EE Ubuntu AddOns Repository to your package manager. See https://linux.ee.ethz.ch/AddTheAddOns for details.
On Debian you can also use the Ubuntu package isgee-vpnc-ethz. For Sarge (3.1) and Etch (4.0) just use the Ubuntu Edgy version of the isgee-vpnc-ethz package.
Download the source of the isgee-vpnc-ethz package and adjust the scripts to your needs.
(Said to no more work. Try the isgee-vpnc-ethz scripts mentioned above in that case.)
Interface name tun0 IKE DH Group dh2 Perfect Forward Secrecy nopfs IPSec gateway 184.108.40.206 IPSec ID Group-Name IPSec secret Group-Password Xauth username n.ethz.ch-Login
Get the whole configuration file including
Group-Password from https://vpnsoftware.ethz.ch/IPSec VPN Client-all OS/Linux/VPNC/Linux-VPNC-ethz.conf. You will need your n.ethz.ch account and password to access that file.
Starting the client
Using the isgee-vpnc-ethz Ubuntu/Debian package