SSL VPN is one of the common modes of VPN that allows a remote user to connect to the corporate network. While SSL VPN can be done via a web browser using https, a more common way is to use a ssl-vpn-client.
Fig. 1. A compilation of SSL-VPN clients supported on contemporary operating systems. Officially supported Linux distributions are shown in Fig. 2.
Fig. 2 is an excerpt from the man NetExtender (Linux man page on NetExtender), which compiles the compatibility list- appliances and OS. As can be seen it also requires a working pppd - Point-to-Point Protocol Daemon (ppp daemon).
NOTE: Please note that Mac OS 10.12 and up do not support NetExtender.
The present study is based on Element, which is a Ubuntu based distribution, installed as a virtual machine on Hyper-V in Windows 10 .
Download
Extraction:
tar xzvf filename.tgz
Installation
NetExtender Client's GUI uses Java runtime. Therefore one has to install a Java Development Kit (JDK) and Java Runtime Environment (JRE). Without them, the NetExtender GUI will not be functional. However, one can still use it by the CLI commands, discussed later in this article. For the present study, only a JRE was installed.
sudo apt-get update
sudo apt-get install default-jre
Java -version
NOTE: Java Runtime Environment (JRE). For the present study, openjdk was and Runtime were used.
sudo ./install
...
Set pppd to run as root [y/N]? y
NOTE: Installing NetExtender from the Package directory. Please notice the prompt Set pppd ... . One has to permit (y) NetExtender to run pppd as the root.
Operation
Further reading: