Please help us problem in installing nginx ufw by terminal

See more:

Linux

Ubuntu

I am getting this error again and agin when I am trying to allow nginx http

ubuntu@ip-172-31-39-67:~$ sudo apt-get install nginx
Reading package lists... Done
Building dependency tree
Reading state information... Done
nginx is already the newest version (1.10.3-0ubuntu0.16.04.2).
0 upgraded, 0 newly installed, 0 to remove and 41 not upgraded.
ubuntu@ip-172-31-39-67:~$ sudo ufw allow 'Nginx HTTP'
Skipping adding existing rule
Skipping adding existing rule (v6)
ubuntu@ip-172-31-39-67:~$ sudo ufw status
Status: inactive
ubuntu@ip-172-31-39-67:~$ sudo ufw app list
Available applications:
Nginx Full
Nginx HTTP
Nginx HTTPS
OpenSSH
ubuntu@ip-172-31-39-67:~$ sudo ufw status
Status: inactive
ubuntu@ip-172-31-39-67:~$ systemct1 status nginx
No command 'systemct1' found, did you mean:
Command 'systemctl' from package 'systemd' (main)
systemct1: command not found
ubuntu@ip-172-31-39-67:~$ systemctl status nginx
● nginx.service - A high performance web server and a reverse proxy server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: en
Active: active (running) since Tue 2018-04-10 11:10:17 UTC; 6h ago
Main PID: 11908 (nginx)
CGroup: /system.slice/nginx.service
├─11908 nginx: master process /usr/sbin/nginx -g daemon on; master_pr
└─11909 nginx: worker process

Apr 10 11:10:16 ip-172-31-39-67 systemd[1]: Starting A high performance web serv
Apr 10 11:10:17 ip-172-31-39-67 systemd[1]: nginx.service: Failed to read PID fr
Apr 10 11:10:17 ip-172-31-39-67 systemd[1]: Started A high performance web serve
lines 1-11/11 (END)
● nginx.service - A high performance web server and a reverse proxy server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: ena
Active: active (running) since Tue 2018-04-10 11:10:17 UTC; 6h ago
Main PID: 11908 (nginx)
CGroup: /system.slice/nginx.service
├─11908 nginx: master process /usr/sbin/nginx -g daemon on; master_pro
└─11909 nginx: worker process

Apr 10 11:10:16 ip-172-31-39-67 systemd[1]: Starting A high performance web serve
Apr 10 11:10:17 ip-172-31-39-67 systemd[1]: nginx.service: Failed to read PID fro
Apr 10 11:10:17 ip-172-31-39-67 systemd[1]: Started A high performance web server
~
~
~
~
~
~
~
~
~
~
~
~
~
lines 1-11/11 (END)

What I have tried:

I am following the exact steps given in the tutorial but the v6 rules are not getting updated and it is saying skipping adding existing rules as you can see from the above code/command. please give me exact commands..i