Symptoms
From within the server, Apache is online and you can telnet locally to the service, however from outside the domains are not connecting.
Description
You encounter browser errors such as
This site can’t be reached
domains server IP address could not be found.
This often means that the port for Apache is not open.
Apache can connect locally
Apache can connect locally
#telnet localhost 443
Trying ::1...
Connected to localhost.
Escape character is '^]'.
^]
telnet> quit
Connection closed.
# telnet localhost 80
Trying ::1...
Connected to localhost.
Escape character is '^]'.
^]
telnet> quit
Connection closed.
But not remotely:
$ telnet 208.43.129.162 80
Trying 208.43.129.162 ...
telnet: connect to address 208.43.129.162 : Operation timed out
telnet: Unable to connect to remote host
Workaround
Verify that the ports are not being filtered.
nmap -P0 -Pn 208.43.129.162 -p80,443
If this shows closed, or filtered, you'll want to double-check the local firewall with:
iptables -L -v -n
For a server using NAT:
iptables -L -v -n -t NAT
The following documentation may also be useful for other firewall ports that need to be opened.