ip-masq and msn messenger transfers?

hi,
ive been having this problem for a while now, im behind a linux box which is running ip-masq on mandrake 9.1 (the box is mine btw), currently i can't get any file transfers incoming through msn (i use trillian for it), is there a relatively uncomplicated and secure way to try and get this to work at all?

or would trying to do this open up too big a security hole for me?

ive looked at the linuxdoc site with no success and im not really sure where else i can look, i googled too but didnt get anything useful either....

i on dialup with a dynamic ip assigned to me each time i connect, if you need more info just say so and i can provide

This was the second hit I had on google.

Quote:

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You can send a file to anyone who has a Passport. (Passports can be granted to any e-mail address). On the File menu, click Send a File To, and then click Other. Type the person's Passport address.
If you are on a local area network that is behind a firewall (as you may be in a corporation), you may be unable to send files to contacts outside of the firewall. If you are in this situation, you can use your e-mail to send files.

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The problem with sending files with messenger is basicly the same as for DCC Send in IRC. Your client will open some random port and the person you're sending the file to connects to this. Because you have a firewall the connect will fail.