fwknop-server software package provides FireWall KNock OPerator server side - C version, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install fwknop-server
fwknop-server is installed in your system.
Make ensure the fwknop-server package were installed using the commands given below,
$ sudo dpkg-query -l | grep fwknop-server *
You will get with fwknop-server package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Administration Utilities |
| Package | fwknop-server |
| Version | 2.6.0-2.2 |
| Description | FireWall KNock OPerator server side - C version |
| Sub Section | admin |