hmm,
well - to summarise your situation...
your provider/admin has a firewall which filters connections outbound right? you can browse the web (http) and retrieve files (http) but not much else?
you are getting a dynamic address from your provider as well.
the lay of the land, as I see it, is that you are sol unless the admin is your mate. The firewall is firstly blocking the majority of well known TCP and UDP ports to the Internet. you have a dynamic address which will mean than the firewall is also probably acting as a NAT device (network adress translation) which means the IP address on your PC is not a real, unique internet address, but hidden behing the firewall as a private address. the firewall translates the address to a real one (probably shared by you and the rest of the nodes on the private network) so there is no way for anyone on the internet to make a connection to you, unless you talk to them first and open a connection.
basically, unless you know the firewall admin, you can forget it, the only way you can get this working would be to run a sharing app like iMesh, Napster etc. and I strongly doubt your admin is that nice, but they may be.
lastly, routers, switches and hubs.
I won't go into vast detail here and the explanation will be a little simplified, otherwise we'd be here all week. <A HREF="
http://www.cisco.com" target="_new">cisco</A> have some good educational materials if you are interested.
right, a hub is a very basic device, originally little better than a piece of wire. it is/was a device to allow many computers on the same TCP/IP to communicate with each other. it has few features and was on a basis of first person talking speaks. imagine the computer signals as a group of people in a crowded room, trying to all shout at each other. Whoever was already talking could talk, but the others must wait for a pause before thay can speak. so it is with a hub, all pcs share the same bandwidth - usually 10Mbs. nowadays hubs have become more advanced and can handle 10 and 100mbs connections and a certian level of tools.
Switches, right, imagine that everyone in that room just got a telephone. now, no-one has to wait, they can call up whoever they like in the rooom and all talk at the same time (except to the same person, in which case they must wait). Switching is like this. every device has the same easy connectivity as a hub (same tcp/ip network) but dedicated bandwidth, not shared. Again speeds are usually 10 or 100Mbs.
Routers are a bit like the postal service. They are designed to send things to computers that are not really local. they are a demarkation. Using TCP/IP the 'letters' must be properly addressed and can travel to the other side of the world but will take a little longer to get there. The router is a junction between TCP/IP networks and sorts data on the basis of IP address, like a telephone number or zip code. The PC must talk with the router in the same way as it would to another PC on the same network and the router will then 'arrange' to forward that data to the correct destination, hop by hop.
so there we go - I hope this helped slightly.
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