I can FTP but no files will transfer!

[joepalm]

I have setup port 21 with TCP on my Router to allow access to my internal LAN address but I cannot file transfer either way. Am i missing something?

Thanks

Tony

 

[CCIEWANNABE]

ftp-data 20/tcp File Transfer [Default Data]
ftp-data 20/udp File Transfer [Default Data]
ftp 21/tcp File Transfer [Control]
ftp 21/udp File Transfer [Control]

Double check that your FTP program is set to access port number 21.

Make sure that your FTP application is set to automatically detect ACSII or binary mode.

Double check that you are attempting to open the correct folder.
Route once; switch many

 

[joepalm]

Thanks for your reply,

I have opened 20/TCP, 20UDP, 21/TCP, 20/UDP and forwarded them all to my Internal IP address but I still cannot download. I have FTP through LAN and it works. I do not have a firewall.

Thanks

 

[jpm121]

Security rights issue? Check rights for your given OS & FTP server prog.

 

[joepalm]

I am using a DSL Nat Router, I have the following ports open but still have problems transferring.

ftp 20/tcp
ftp 20/udp
ftp 21/tcp
ftp 21/udp

Ports 1024-6000 open with TCP

Thanks

 

[TheOldMan346]

tvale,

If you are using a DSL NAT router, you are running a firewall. That is what Network Address Translation (NAT) does for you.

What software are you using for FTP. Is it an FTP Client or a web browser. The difference is in whether you are using Active or Passive mode FTP. FTP Clients usually give you a choice while browsers like IE and Netscape typically use Passive (PASV) mode.

In Active mode the app uses port 20 to transfer the data and port 21 to pass control info. In PASV mode, you connect to the FTP server and the browser issues the PASV comand which instructs the server to use passive mode. The server then picks a random port and advises the browser which port it is listening on. The transfer then occurs on that random port. You've opened ports 20 and 21 but if you are using PASV mode, your firewall is probably blocking that random port.

Here is a description of how it works.

http://www.phoneboy.com/docs/pasvftp.html

Hope that helps.
The Old Man

 

[joepalm]

Thanks for your reply,

The client I am actually using is a Backup Utility for Internet backup, my Host is the Server. I am using Passive mode but which random port do I open on my Nat Router?

Thanks

 

[TheOldMan346]

It's random. It picks a port in a range but you don't know in advance what port it will be to open it up. You can open a whole range of ports but that will lessen the security.

See if there is a setting to disable PASV mode and use Active mode. That will restrict it to use only ports 20 and 21.

Hope that helps.
The Old Man

 

[joepalm]

I have 1024-6000 open using TCP, could it be outside of this range that I am having this problem?

Thanks

 

[TheOldMan346]

It's a little more complicated than just opening up a bunch of ports. Not knowing your network/router setup, let's assume your computer is at 192.168.1.100 and you router is 192.168.1.1. Let's also say your router's public IP from the ISP is 123.4.5.6.

Using PASV mode, your computer opens a connection to the FTP server using port 21. It issues the PASV command and the server responds using the open connection on port 21 with the new port number that it will be listening on. Your application, then, will try to open a connection to the FTP server using the port that the FTP server will be listening on. This port will be where the transfer will occur.

Since your host is the server, here is what happens using the addresses we assumed above. Remember that your router is doing NAT and anyone outside of your LAN only knows you by the router's public IP address of 123.4.5.6.

[ol][li]The Internet Backup app starts (?) and opens an FTP connection with your host. Not sure how this connection starts and who initiates it. [/li]
[li]Since it is PASV mode, your host responds that it will be listening at 192.168.1.100 on port 12345, for example.[/li]
[li]The backup app tries to open a connection to 192.168.1.100 and port 12345 but can not do it since your router is translating the address[/li][/ol]

There is likely more involved since I don't know the details of your environment but I would guess this is pretty close.

Hope that helps.
The Old Man