preferret是 較喜歡加密的點對點連線
-er --encryption-required Encrypt all peer connections
all都要加密
-ep --encryption-preferred Prefer encrypted peer connections
以加密為優先,or 較喜歡*預設
-et --encryption-tolerated Prefer unencrypted peer connections
較喜歡非加密.
設定為er時,把port 1723 tcp打開
http://ejesconsulting.wordpress.com/2009/07/20/bittorrents-in-freenas/