Soulseek client.
Go to the router admin panel, port forwarding part.
It can be found using your browser under a magic vendor dependent address.
On a D-Link for example the default is: http://192.168.0.1/RgForwarding.asp, default login: admin pass: motorola.
Open ports 2234 to 2239 on local ip found at:
ifconfig eth0 | grep "inet addr:"
Now either put your files in another partition at the root, or symlink your share and download dirs to somewhere above user so that people cannot see your username:
sudo ln -s /home/soulseek path/to/share/folder