Networking Questions
 

hello

today, i was arguing with some guy (no names) over three networking issues. this guy seemed to argue with me over the fundamentals of internet connections and was convinced that he was right. i just want to run these by to make sure that im not this stupid. if im am, then my views on netwoking are seriously scewed.

1) for example, if you have 6MB/s download and 3MB/s upload and you are capping your uploading at 3MB/s, you still have 3MB/s download, right? this guy seemed to think that all your download would be used.

2) this guy claimed that bittorrent hogged up all "network resources". even if you weren't capping your download speed (i.e. using all 6MB/s downloading a torrent), he says bittorrent still uses those "resources" and wouldn't let anyone else on the network have them. i do know that while you are downloading a torrent, bittorrent continuously searched for new seeds, but that doesn't take up all bandwidth.

3) i am in a vpn network at my dorm room running fedora core 4. i went and hand-customized my iptables to only allow smb, ftp, and http within my router. this guy claims that, since i am attached to the dorm firewall and server, the server can port-scan my computer and gain access to my files and search my computer. again, i have my router block all incoming connections and my iptables block all incoming connections except those ports mentioned earlier.

im almost positive that this guy is wrong, but i need outside assurance as to weather this guy needs institutional help.

thank you
andrew

I don't know TOO much, but maybe i can answer your questions.

1) I'm pretty sure that if you have a 3 MB/s upload and 6 MB/s download, you can upload your max (3 MB/s) and download your max (6 MB/s) simultaneously.

2) No, bittorrent uses the amount of bandwidth that it says it's using. Mine, however, tends to use up my max most of the time. I can still access the internet, though. It's just slow, just like when downloading any file.

3) If you aren't blocking ports 21, 80, and 139 then the server or anyone inside it's firewall WOULD be able to port scan you and get your files... at least within those protocols. Keep in mind, there are ways to hack into linux boxes, especially in the upper-range ports. (I think the X server has some sort of UDP port open between 32000 and 65000 that a port-scanner could reveal)

don't quote me on this stuff, but this is what I think.