i have two computer A & B. both are use dial-up connection connected to internet, but A use ISP a, B use ISP b.
from A i can make a tcp connection to B, but I can't make a tcp connection from B to A.
the tcp connection can only be initiated by Computer A. why?
how can i initiate a tcp connection from B?
as i know, icq use tcp connection between users, i can do message chat between the above A & B, it doesn't matter which one start the chat.
why icq can make a tcp connection from B to A and I can't establish tcp connection if i run my own program. why?