First determine if you can do what you want with network manager, from your post I think that is unlikely.
If you are not going to use Network manager, you will need to either remove it or disable it and understand how to manually configure your network.
sudo apt-get remove –purge network-manager network-manager-gnome
Bring the network down
sudo /etc/init.d/networking stop
You would then set your nameserver in
sudo -e /etc/resolv.conf
You then edit
sudo -e /etc/network/interfaces
Something like this
iface lo inet loopback
iface eth0 inet static
broadcast 111.222.333.444 #I am not sure of your broadcast
You can then use the up/down options, the syntax is
So in your case, add in
up echo $(date) "eth0 up" >> /var/log/journal
down echo $(date) "eth0 down" >> /var/log/journal
Add those commands in in the eth0 stanza, below gateway.
Likewise, date is very flexible, and the options are covered in the man page
date +"%d-%m-%y %l:%M:%S"
That at least is going to get you in the ball park.