SSH Connections & Port Forwarding

[witkedm]

My questions relate to SSH tunneling and port forwarding using Putty. I don't have a deep understanding of SSH, but I was able to set up a SSH server at home and use the Putty client to surf the internet (on a wireless laptop) through a proxy with Firefox.

To do this, I start Putty and have it set up to establish a tunnel on ports 9999 (for internet proxy) and 5900 (for VNC software). My home SSH server asks for the usual user name and password and that works fine. If I start Firefox at this point (with the proxy settings on), my connection is refused. If I look in the Putty event log, it doesn't mention anything about ports 9999 or 5900 being forwarded. I rechecked my Putty tunnel settings for the profile I use and these port forward commands are there. It isn't until I run the following command in the Putty client command window that Firefox will connect:

ssh -ND 9999 username@domainname.com

I don't fully understand why Firefox isn't connecting after I start the putty client with the preset tunnels. If the even log is correct and I understand it correctly, the tunnels are not being established when I start Putty. If that is the case, I have no idea why that is not working.

I also don't fully understand what the ssh line of code I have shown above does. I get the ssh and username@domainname.com parts, but what does the -ND portion do?

Another question related to the Putty event log. After I do run the ssh line code and get Firefox up and running, each time I visit a site the event log shows the forwarded port being opened and closed. The browser is working fine so I assume the opening closing functions are the way SSH/Putty is supposed to work - is this a correct assumption?

One more question (I promise). In the Putty client window I have noticed that while I am web surfing and using the SSH tunnel, some of the channels (i.e. 5,6,11,2) fail and get a refused connection. The exact error message is: Channel X: open failed: connect failed: Connection refused. When this happens, the web page I was surfing to usually does not load. If I hit refresh - the page comes up. I assume a new channel is being used. What exactly are channels and should I be worried that some of them can't connect?

Thank you for any info/help on these mysteries

[pam123]

My understanding of PuTTY is even less then yours so this post serves as a "bump" to keep your question in view.
I will point out that a program for remote access and encryption could have safeguards that would prevent it from making automatic connections by default.