I have attempted to open port 443 on a server I'm working on (Ubuntu 16.04):
/sbin/iptables -I INPUT -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
The port doesn't appear to be open:
nmap cubicverse.com
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT tcp -- anywhere anywhere tcp dpt:https state NEW,ESTABLISHED
ACCEPT tcp -- anywhere anywhere tcp dpt:433 state NEW,ESTABLISHED
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:https
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
I have also opened the port with ufw.
What alternative steps may be needed to open the port?
To be clearer, I am attempting to add an SSL cert for this server, and the 'SSL checker' keeps telling me I have a closed port and hence it can't validate the CSR.
There's a typo in your firewall configuration. You want to allow port 443 not port 433.