I have an Ubuntu box running Ubuntu 12.04 LTS server edition, which acts as a DHCP server and is also the gateway for my network. IP forwarding is turned on. Additionally, the server acts as a secondary DNS for websites I host. I am looking to install ownCloud on the server, and that's where my question arises.
When I attempt an SSH connection to the server from behind the server, using its public IP address, the connection times out. I assume this is because it appears that my computer is using the same IP address, and that creates an issue at some point along the way.
I'm worried that installing ownCloud on the server will produce the same issue. In other words, if I create a DNS record for cloud.mydomain.com, that points to the server's public IP address, then I worry that if I try and access cloud.mydomain.com from behind the server (and thus, because of IP forwarding, appear to have the same IP address as the server), I simply won't get a proper response.
If this is the case, how do I fix this?
Thank you so much!
UPDATE: Let me provide more information about the setup, as it may be relevant. The server has Shorewall installed. All necessary ports are open. IP_FORWARDING in shorewall.conf is set to On. The server itself sits behind a NAT. So it amounts to a NAT within a NAT. I know this isn't the best setup, but it's what I'm stuck working with. The DSL modem that generates the first NAT is configured to forward all open ports (in this case, 22, 53, and 80) to the server. The server provides DNS for the outside world, and for my local network. Today (12/5) I set up Apache on the server, opened port 80 on both the server and the modem, and the problem persisted: I can access the default Apache page from outside my network, but not from behind the server. Any help you can provide would be much appreciated!