i'm trying to set up an ftp server on my computer and i am having a frustrating time getting it to work. i'm running serv-U on my computer which is behind a linksys router. i've configured the router to forward port 21 to the computer running serv-U. i've also set up a domain on serv-u using port 21 and set up a couple of accounts under that domain. furthermore, i've disabled my firewall (for now) just to make things as simple as possible. with my current set up, i have no problem using a ftp client on another computer connected to the same router to access the ftp server, but when someone over the internet tries to access it, they can't connect. my internet provider assigns me a dynamic IP address, so i always look it up and input that address as the host on the ftp client, set the port to 21, and enter the valid login and password. so from what i've said, can anyone please tell me what i am doing wrong or am forgetting to do?? btw, my dsl provider is sbc...if that matters.

 

If you have another computer on your network, try to FTP in that way.

Ping the FTP server name, get that IP then try to connect to that local address.

If that works fine, then SBC probably blocked that port. I have a cable modem and have FTP running on my dynamic IP.

 

ftp works fine locally within my network. it just doesn't seem to work from the "outside". i was kinda suspecting that sbc blocked port 21, and so tried setting up a domain using port 2121, but even that doesn't seem to work. do you know of any other ports other home users use that are successful in setting up an ftp server??

 

You might try something simple like making sure that the port is successfully going to the right computer. Since you know the FTP service is set up correctly, try to connect to your dynamicIP address within your network.

I think you said you did port forwarding into your FTP server, just make sure you forward the right port within your firewall / router.

 

The problem is somewhat complex. I have done the same thing you are doing, and it took me a while to get it working.

Your ftp server receives commands on port 21, but transfers data on a higher port, chosen pretty much randomly. Either the remote ftp client of the server determines this port. You probably want to set the server to use passive mode, which means the server will set the ports for data transfer. You can specify the range for data transfer with Serv-U, see the knowledge base article at the top of the list here (#1044):
http://rhinosoft.com/kbsearch.asp?prod=su

Also, as it says, you need to tell the ftp server what IP address it should "pretend" to be when communicating with remote clients. For example, if a remote ftp client connects, the server will tell it to use ports 2000-2010 for data transfer, at IP address XX.XX.XX.XX. You want this address to be your ISP-assigned address, obviously, instead of your internal network IP, which it uses by default.

It can be a real pain getting this working, and not having a static IP makes it even tougher. Hopefully this helps.

 

Did you reboot the router?