What it is:
Direct connect is a peer-to-peer (P2P) file-sharing protocol. Clients
connect to a central hub where they can view a list of clients or
users connected to them. Users can search for files and download them
from other clients, as well as chat with other users.
The most popular Windows client implementing this protocol currently
is DC++. LinuxDC++ is a Linux port of DC++. Though it is primarily
aimed at Linux, it has been shown to work on other Unix-based
operating systems as well.
To know more about:
To install in Ubuntu:
sudo apt-get install linuxdcpp