Direct Connect is a peer-to-peer file-sharing protocol. Direct connect clients connect to a central hub and can download files directly from one another. An old implementation is known as NMDC (NeoModus Direct Connect), a new one is ADC (Advanced Direct Connect) which includes a lot of improvements.
Direct Connect clients
LinuxDC++ is a Direct Connect client based on DC++. Utilizing the latest DC++ core, LinuxDC++ offers similar functionality to the Windows client like segmented downloading, TTH based file integrity, etc. with a GTK+ user interface
# aptitude install linuxdcpp
EiskaltDC++ is a program for UNIX-like systems that uses the Direct Connect and ADC protocols. It is compatible with other DC clients, such as the original DC from Neomodus, DC++ and derivatives. EiskaltDC++ also interoperates with all common DC hub software.
# apt-get install eiskaltdcpp
Advanced Direct Connect hubs
uHub is a high performance peer-to-peer hub for the ADC network. Its low memory footprint allows it to handle several thousand users on high-end servers, or a small private hub on embedded hardware.
# aptitude install uhub