On Debian Linux systems conntrack uses the /proc/net/nf_conntrack device. This
device may not be available in other Linux variants (e.g., Ubuntu). Sebastian
Monte provided information about how conntrack can be used in those cases. His
findings are summarized below:


If you want to use conntrack with Ubuntu issue the following commands:

   1:   apt install pkg-config libfuse-dev
   2:   mkdir /opt/scriptfs
   3:   cd /opt/scriptfs
   4:   wget https://github.com/frodonh/scriptfs/archive/refs/heads/master.zip 
   5:   unzip master.zip
   6:   cd scriptfs-master
   7:   make
   8:   ln -s /opt/scriptfs/scriptfs-master/scriptfs /usr/bin/scriptfs
   9:   mkdir executable
  10:   mkdir conntrack
  11:   echo 'conntrack -E' > executable/conntrack.sh
  12:   chmod +x executable/conntrack.sh

Now we have a directory /opt/scriptfs which looks like this:

    drwxr-xr-x 2 root root  4096 Apr 16 18:34 conntrack
    drwxr-xr-x 2 root root  4096 Apr 16 18:34 executable
    -rw-r--r-- 1 root root 57065 Apr 16 17:53 master.zip
    drwxr-xr-x 2 root root  4096 Apr 16 18:02 scriptfs-master

Finally do:

  13:   insert 
            #!/bin/bash 
        at the first line of /opt/scriptfs/executable/conntrack.sh
  14:   scriptfs /opt/scriptfs/executable /opt/scriptfs/conntrack
  15:   in etc/natlog.conf specify
            conntrack-device: /opt/scriptfs/conntrack/conntrack.sh




