There are many servers support PORT(active transfer mode) only, and 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 the FTP directory because the server has no idea to connect on 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 the internal network, the FTP client sends a PORT 192,168,1,2,9,6 to the server and does listing. This command tells the server, "hello, I am ready, and please connect to 192.168.1.2". But how? The server has no chance to connect to 192.168.1.2 because it is not a valid internet IP address!
The right way is FTP clients should send an internet IP address, for example,PORT 220,96,1,12,9,6 , and tells your router if there have an incoming connection and port is xxx, please forward it to your computer, that's what UPnP does, and it called "UPnP Port mapping".
Some FTP clients require Windows XP or above to using UPnP Port mapping, 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 on 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.