Messages in this thread | | | From | Jos Vos <> | Subject | Re: IP MASQUERADING broken again from v1.3.81 onwards | Date | Fri, 05 Apr 1996 14:55:30 +0200 |
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> port 20 is ftp-data, but this port is not used even if you do *not* use > a firewall. the client and the server negotiate which port to use > by using the PORT command, part of the ftp-protocoll.
Yes, but port 20 is normally used as remote port for the ftp-data connection going to that local (negotiated) port. So that's why you will normally see it listed using ipfwadm -Mln.
> you can *NEVER* ftp through a "closed" firewall except when using > passive mode, see the PASV command, part of the ftp-protocoll.
This depends on your definition of a "closed" firewall. The special treatment of the FTP PORT command *does* allow you to use it in combination with IP masquerading, *without* using passive mode.
-- -- Jos Vos <jos@xos.nl> -- X/OS Experts in Open Systems BV | Phone: +31 20 6938364 -- Amsterdam, The Netherlands | Fax: +31 20 6948204
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