[Ilugc] ports and sockV

[arvind vanam]

i have actually 2 things to know..

1) how can i manually open/close/block ports in linux (in terminal)?

2)what is sockV proxy and can i change the port on which we can access
it,that is,port no. 1080 .

Actually we have a LAN setup at our hostel and on one computer we have
internet connection.it has 2 network cards one connected to internet and the
other like other nodes is connected to LAN.Now when we use bit torrent
clients we have to specify the proxy as 172.31.1.15:1080 where
172.31.1.15is the local address of the node which is directly
connected to internet.

   i)so why do i need to specify this proxy?
   ii)and can i change the port no. for the sockV proxy on 172.31.1.15 ?(i
have the access to this node)