I set up a linux server on an AMD Athlon X2 64 -based PC using the network install ISO from Debian.org. Static IP of 192.168.1.200, SSH installed and forwarded to port 22 on my router. I can now access the server from any computer within my LAN using Putty with no problems.

I also installed Apache and am able to view the placeholder web page when I enter 192.168.1.200 from my LAN computers.

I then registered at Dyndns.org, entered my ISP-provided IP in the box, and set up Dynamic DNS through my router firmware. When I enter the dyndns address from behind my LAN, I get my router's login screen, which tells me that it updated. However, when I try to access the domain from an outside computer the connection times out. It seems like it is not making the link somewhere but I cannot seem to find out what I am doing wrong. Any insight would be appreciated.

That is normal behavior for some routers.

There are two places to start:
1) Make sure port 80 is being forwarded from your router to your server
2) Make sure your server's firewall isn't blocking the connections.

If those two things are fine, then the next step would be to check the Apache logs and see if the requests are even getting there from the outside world. If they're not, you'll either have to set up some firewall rules to see what is happening or use a tool like wireshark to see if the packets are making it past your router.

Your ISP may block port 80, they often do. They think running a webserver is commercial activity and do not allow it on home-grade connections. Workaround is to run server on some other port, I believe there is a dyndns option to redirect transparently. You can check if ISP is blocking the port with Shields-Up, all ports that are not blocked by you are blocked by ISP.

While you're checking, be sure to look at /etc/ddclient/ddclient.conf (wherever you have ddclient.conf installed) and double-check your settings, particularly the router settings (which can be a pains sometimes).

I did fiddle with the "router" settings (I have a Linksys BEFSR41) and fiddled too much to get and keep it going, so I switched to the "web" settings (rather than the "router" settings); works fine. Parts of my configuration file look like this:
If you try the "web" and everything works, then you can go back to the "router" and fiddle until you get it, eh?

Hope this helps some.

Ok I went into the router this morning and saw that I did NOT have HTTP set to forward to port 80, so this could have been the problem. I don't want to install Putty on a work computer, but if I can get this part of it working it it should indicate that the DynDNS is functioning properly.

Good point. If it still doesn't work after all this should I use port forwarding to set HTTP to a higher value as in:

HTTP - TCP Any -> 40,000 ?

I went to edit the file using pico and it appears ddclient.conf is not installed. I use apt-get install ddclient an error and it doesn't install:

I tried that last night and this morning. I was able to apt-get install/remove other programs, so the internet connection is working.

Then I run apt-get update and I get:

I am fresh out of ideas.

Have you tried reading the information at https://www.dyndns.com/services/dns/dyndns/howto.html?

Might be worth a shot, eh?

Thanks for the link. I went through thir page, and also tried their port diagnostic tool, and it is telling me it is blocked. I have tried disabling all of the firewalls and it still does not resolve through dyndns's open port tool (http://www.dyndns.com/support/tools/openport.html). It appears port forwarding is set up correctly.

I can't seem to trace down if it is an issue with the router or the server? Again, Putty connects to it through SSH fine and I can access the placeholder website through the browser, both on the LAN side.

If this is an indication that you have Verizon as an ISP, then it is nothing you're doing. Verizon is a known scumbag, er, I mean blocker, of port 80 for residential users. You'll have to move to a higher port if Verizon is your ISP.