add iptables drop

[maple11041]

Add ip iptables drop and remove editing log file

[maple11041]

I added the iptables drop mentioned in issue #4 , so that the script is fully working now.
Also, I don't think it's necessary to edit '/var/log/auth.log' in PR #3 , my system log stop working after modifying the log file.
I had to restart my system log like so https://askubuntu.com/questions/615457/no-logs-are-written-to-var-log
It works fine without editing the log file. (Tested on Ubuntu 18.04)