fwknop-client software package provides FireWall KNock OPerator client side - C version, you can install in your Debian 8 (Jessie) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install fwknop-client
fwknop-client is installed in your system.
Make ensure the fwknop-client package were installed using the commands given below,
$ sudo dpkg-query -l | grep fwknop-client *
You will get with fwknop-client package name, version, architecture and description in a table
| Distro | Debian 8 jessie |
| Section | Administration Utilities |
| Package | fwknop-client |
| Version | 2.6.0-2.1+b1 [amd64, armel, ar |
| Description | FireWall KNock OPerator client side - C version |
| Sub Section | Admin |