To connect to vpnc without using the vpnc manager install vpnc using
sudo apt-get install vpnc
Then create a file mycnf.conf containing the following information
IPSec gateway xx.xx.xx.xx
IPSec ID xxx
IPSec secret xxx
Xauth username xxx.xxx
Xauth password xxx
where xxx need to be replaced by your network and account details. You may not need to use all the settings (all the lines), or you may need to add more settings (more lines) into that file. This depends on your network properties.
Then replace the default vpnc configration file by
sudo mv mycnf.conf /etc/vpnc/default.conf
Then connect with
sudo vpnc-connect
To disconnect use
sudo vpnc-disconnect