MSN uses these settings for file transfer.
File Transfer
File Transfer (FT) requires that the initiating station pass its address to the FT peer in the session exchange through the server. Because of this, the first issue listed under application sharing and whiteboard applies:
• The address provided by the initiating station might be an internal address that is translated by a NAT device. This is an invalid address for the peer to use for the TCP connection.
The TCP connection for file transfer, which could be initiated by the external party, presents an additional issue.
• Both incoming and outgoing TCP connections use the range of ports from 6891 to 6900. This allows up to 10 simultaneous file transfers per sender. These ports must be open on any firewall between the peers. If you open only port 6891, users will only be able to do one file transfer at a time.
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This is the whole file