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bigstar · 08-10-2002, 02:36 PM

Many routers are not compatible with FXP because they use NAT (Network Address Translations)

NAT provides protocol helpers which monitor known protocols and corrects any mistakes made by by the users software.

For example on a basic LAN w/ router you may have a network IP of 192.168.0.1 and a external IP of 69.11.52.115. To all of the applications on your system your IP is 192.168.0.1

When performing basic FTP commands the client may send the PORT command which is your IP (192.168.0.1) followed by the port, behind a router this IP would be incorrect, and when performing a FXP transfer PORT uses the IP of the other FTP server.

Now NAT automatically changes the IP to match your external IP, which in turn breaks FXP.

Normally NAT only monitors port 21 for the FTP protocol so running the FTP servers on a non-standard port (i.e. 245) should eliminate the problem.

08-10-2002, 02:36 PM
bigstar FlashFXP Developer Join Date: Oct 2001 Posts: 8,012	Many routers are not compatible with FXP because they use NAT (Network Address Translations) NAT provides protocol helpers which monitor known protocols and corrects any mistakes made by by the users software. For example on a basic LAN w/ router you may have a network IP of 192.168.0.1 and a external IP of 69.11.52.115. To all of the applications on your system your IP is 192.168.0.1 When performing basic FTP commands the client may send the PORT command which is your IP (192.168.0.1) followed by the port, behind a router this IP would be incorrect, and when performing a FXP transfer PORT uses the IP of the other FTP server. Now NAT automatically changes the IP to match your external IP, which in turn breaks FXP. Normally NAT only monitors port 21 for the FTP protocol so running the FTP servers on a non-standard port (i.e. 245) should eliminate the problem.