NAT'ed hosts are not able to create magnet links unless they do port-forwarding and force their IP address.

You can also send magnet links via eMail.

The magnet can't be made client specific. BearShare and Acquisition might also parse those magnet links.

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Morgens ess ich Cornflakes und abends ess ich Brot
Und wenn ich lang genug gelebt hab, dann sterb ich und bin tot

--Fischmob