How to run Nginx on a different port other than 80 - nginx

Question

I cannot run Nginx because port 80 is already listening on a docker-proxy service.
tcp6 0 0 :::80 :::* LISTEN 13110/docker-proxy
I would like to run Nginx on port 8800 instead of the default port 80.
As such, I've edited the default file as below;
sudo nano /etc/nginx/sites-available/default
listen 8800 default_server;
listen [::]:8800 default_server;
listen localhost;
However, I still cannot get it working as expected even after restart.
What am I doing wrong and how can I resolve it?
Below is the error I get;
● nginx.service - A high performance web server and a reverse proxy server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Fri 2019-04-26 04:23:14 EDT; 13min ago
Docs: man:nginx(8)
Process: 16955 ExecStart=/usr/sbin/nginx -g daemon on; master_process on; (code=exited, status=1/FAILURE)
Process: 16944 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=0/SUCCESS)
Main PID: 80941 (code=exited, status=0/SUCCESS)
Apr 26 04:23:11 ubuntu systemd[1]: Starting A high performance web server and a reverse proxy server...
Apr 26 04:23:11 ubuntu nginx[16955]: nginx: [emerg] bind() to 127.0.0.1:80 failed (98: Address already in use)
Apr 26 04:23:12 ubuntu nginx[16955]: nginx: [emerg] bind() to 127.0.0.1:80 failed (98: Address already in use)
Apr 26 04:23:12 ubuntu nginx[16955]: nginx: [emerg] bind() to 127.0.0.1:80 failed (98: Address already in use)
Apr 26 04:23:13 ubuntu nginx[16955]: nginx: [emerg] bind() to 127.0.0.1:80 failed (98: Address already in use)
Apr 26 04:23:13 ubuntu nginx[16955]: nginx: [emerg] bind() to 127.0.0.1:80 failed (98: Address already in use)
Apr 26 04:23:14 ubuntu nginx[16955]: nginx: [emerg] still could not bind()
Apr 26 04:23:14 ubuntu systemd[1]: nginx.service: Control process exited, code=exited status=1
Apr 26 04:23:14 ubuntu systemd[1]: nginx.service: Failed with result 'exit-code'.
Apr 26 04:23:14 ubuntu systemd[1]: Failed to start A high performance web server and a reverse proxy server.

Answer 1

You have to go to the /etc/nginx/sites-enabled/default
Edit that file and put (If you are willing to put "8800" as your port for nginx)
server { listen 8800; }
The start the server
sudo service nginx start
or
sudo service nginx restart if previously running.
Then access localhost:8800
Add a rule to iptables
vi /etc/sysconfig/iptables
-A INPUT -m state --state NEW -m tcp -p tcp --dport 8800 -j ACCEPT
Restart IPtables
sudo service iptables restart;

Answer 2

It looks like the problem is in the line
listen localhost;
The "listen" directive can take a port number, a host,
or both. I believe in your case this line defaults
the port to 80, which would cause the problems you
are experiencing.
Also, beware if "default" is not the only file
in hosts_available. Each of these (each server block) will default
to using port 80 unless overridden there. Just
editing "default" would not be enough in that case.

Answer 3

I found this answer on Server Fault helpful: https://serverfault.com/questions/655067/is-it-possible-to-make-nginx-listen-to-different-ports
You can add ports to the one server block to keep things simple:
server {
listen 80;
listen 8000;
server_name example.org;
root /var/www/;
}