There are many servers support PORT(active transfer mode) only, it means the server will try to connect to your computer when you do file downloading or browsing. Under this condition, you may can't do transfers or browsing FTP directory because of the server have no idea to connect in your computer.
We have received some emails from our customer and said our FTP client can't list directory
after sent the PORT command. Let's explain it now:
When you are inside internel network, the FTP client sends a PORT 192,168,1,2,9,6 to server and do listing, this command tells server "hello, I am ready, please connect to 192.168.1.2". but how? the server have no any chance to connect to 192.168.1.2 because of it is not a valide internet IP address!
The right way is FTP clients should sends a internet IP address for example PORT 220,96,1,12,9,6 and tells your router if there have a incoming connection and port is xxx, please forward it to your computer, that's what UPnP does and it called "UPnP Portmapping".
Some FTP clients requires Windows XP or above to using UPnP Portmapping, but our FTP client implements the native UPnP supporting even if you are using Windows 9X!
What you need to do?
1. A router with UPnP option enabled.
2. Open the UDP port 1900 for our FTP client if you have a firewall installed in your computer.
The UPnP feature is compatible with these routers
1. Alacatel Speed Touch 510 v4
2. AVM FRITZ!Box Fon
3. Belkin F5D7231-4 802.11g Wireless Cable/DSL Gateway Router
4. BEWAN BOOSTER 32 G Firmware v2.54.2w104
5. Dlink DI-604
6. Edimax BR-6114WG(G) WIRELESS Router
7. Linksys Wireless-B Broadband Router BEFW11S4
8. Netgear WGR614
9. SafeCom (SWAMR-54108)
10. TP-Link WR245
11. U.S. Robotics 802.11g Wireless Router
12. W-Linx MB-401S (identical to SMC 7004BR)
13. Linksys routers with Tomato Firmware
If you have a router not in the list, please let us know, thank you.