Connection

Listening Port

• The Port used for incoming connections field specifies the port that BitTorrent Mainline should use to listen for incoming connections. This port must be unfirewalled for optimal usage of BitTorrent Mainline. Setting the port to 0 indicates to BitTorrent Mainline that you would like for it to select a random port after the changes are confirmed.
• The Random port button selects a random port between 10000 and 65000 as the listening port.
• Enable UPnP port mapping allows BitTorrent Mainline to communicate with the router to forward a port without your manual intervention. Some devices do not support Universal Plug and Play (UPnP), so you might still have to forward your ports manually. Disable UPnP if that is the case.
• Enable NAT-PMP port mapping allows BitTorrent Mainline to attempt to forward a port with routers that support the NAT port mapping protocol (Apple products, for example).
• Randomize port each start makes BitTorrent Mainline select a random port between 1000 and 65000 to use at startup. Note that this option might conflict with your port forwarding settings, so if you manually open ports in your router and firewall, it's best to leave this option disabled.
• Add Windows Firewall exception allows BitTorrent Mainline to add an entry to the Windows Firewall exceptions list that lets it bypass the firewall. This is useful only if you actually have Windows Firewall enabled. Note that this option works only on operating systems released after (and including) Windows XP with at least Service Pack 2 (SP2) installed.

Proxy Server

• The Type dropdown menu specifies the type of proxy you are trying to use.
• The Proxy field is where you enter the proxy's URL or IP address.
• The Port field is where you enter the proxy's port.
• Checking Authentication indicates that you need to log into the proxy server in order for it to work.
  
  • The Username field is where you enter the username required to log into the proxy server for authentication.
  • The Password field is where you enter the password required to log into the proxy server for authentication.
• Resolve hostnames through proxy forces BitTorrent Mainline to perform reverse DNS lookups through the proxy.
• Use proxy server for peer-to-peer connections forces BitTorrent Mainline to communicate and transfer data with peers through the proxy. By default, this option is disabled, and BitTorrent Mainline only uses the proxy to communicate with trackers.