Port Forwarding with DynDNS

Have you tried it from outside your local network?

When you are on your local network use vnc://192.168.2.4
When you are outside your local network use vnc://<my host>

 

Is there a firewall active at the computer?

Is there a firewall active at the computer?

 

Where are you typing vnc://<my host>?

I do this all the time from Finder -> Go -> Connect to Server so it should be working...

You have remembered to enable screen sharing in your system preferences settings?

Sorry if the above is blindingly obvious to you, just trying to cover the bases

As regards FTP (port 21), are you getting as far as the initial prompt or just not seeing anything? For example using a telnet command from the terminal like the following should come back with a banner. If you're getting that far but are still having problems then you need to Google passive mode FTP.

iMac:~ $ telnet ftp.server.net 21
Trying 192.168.0.3...
Connected to ftp.server.net.
Escape character is '^]'.
220-Microsoft FTP Service
***************************************
* This is a private system *
* Do not attempt access without *
* relevant authorisation! *
220 ***************************************

(Names and addresses changed to protect the guilty...)

If you're still struggling then you could resort to using the tcpdump command, the standard packet sniffer. Something like the following should show you if vnc packets are getting as far as the ethernet interface on your computer:

sudo tcpdump port 5900

Then attempt the connection and watch for output.

 

As a rule of thumb, never have your router configuration accessible from the internet unless you have a _very_ strong password, as an attacker could easily guess your admin password and then disable your firewall, something you don't want to happen any time soon.

 

I actually work on DynDNS Ninja Squad (ie: the support team). That behavior you are seeing sounds like a loopback connection issue:

http://www.dyndns.com/support/kb/loopback_connections.html

Let me know if you have further questions, I will be glad to assist.

 

I was just doing my normal browsing around the MacRumors forums and stumbled across this post quite accidently. Even though I am off the clock, I am glad to help you out.

Basically a loopback connection issue is caused by the router being confused which interface to forward the connection request to. Many routers will have settings (such as NAT redirection) that you can toggle to fix the issue. Like you said, as long as it isn't a big deal to not have access on your internal network, it shouldn't be an issue for you.

Few things you can do. Make sure your router's admin page is not accessible remotely from the Internet. Usually the router will have a setting to disable remote admin access. Make sure it is disabled and that should prevent any hacker from changing your router's settings. Doesn't hurt to give the router a unique password either to make things a tad more difficult.

We offer no password protection services for your DynDNS hostname. DynDNS is just a DNS service, so your computer asks what the IP address for example.dyndns.org is and we respond with the current IP address we have on file. At that point, we are out of the picture, as your computer will then connected directly to that IP address assigned to the hostname.

What I highly recommend doing is having a strong VNC password on your Mac. Plus it probably wouldn't hurt to look into SSH tunneling for extra security.