Airport Extreme & FTP

FTP can be somewhat tricky to port forward. I have an AEBS, but haven't experimented with allowing in-bound FTP into my network.

Try checking the connection coming in to see what mode FTP is using. Passive mode usually works better than active mode when you have to traverse a firewall. For most all FTP clients other than Microsoft's command line version FTP client, passive mode is the default.

If possible, pick FTP as an application you want to forward, rather than just listing ports 20 and 21. The router needs to be able to associate the data and command channels of the FTP session as two parts of the same logical conversation. Apologies in advance, if you already did it this way.

The other thing that might be getting in your way is the MTU size is too big. It could be that usually the packets are under 1500 bytes until you list a big directory and then that takes several packets to send the listing. That long directory listing may be lost if its consecutive full 1500 byte packets can not be fragmented and correctly reassembled as they traverse the route. This can be tough to trouble-shoot as the packets my be silently dropped somewhere mid-route.

You may need to try setting the MTU size on your broadband router and/or the computer hosting the FTP site. Try setting to 1300 for the MTU and work your way up towards 1500 until you find the biggest MTU packet size that works. I've found that DSL links occasionally need MTU manually set to less than 1500. MTU should be auto-probed, but apparently that isn't always reliable.

Bill

Same problem here 😟

@Apple; please fix this! Oh and add DynDNS while you're at it 😉

I am having the exact same problem and it's driving me crazy. For the life of me no mater how many ports I open up, even when I turn off the firewall on the computer and set up the computer as a wide open dmz host with the airport extreme base station, I can't get that little fetch dog to stop running when I try to connect from a remote location.

I know I'm missing something, but I can't figure out what it is. Has anyone had luck getting ftp to work behind the base station?

I have no problem with both FTP and SFTP. I port forward 20, 21, and 115. I use Fetch. Notice that SFTP did not work with the AEBSn until version 7.2.1 . See below:

http://fetchsoftworks.com/news/ftp-with-tlsssl-and-the-new-ai.html

I was having a similar problem. Ended up using port 2121 for my FTP and it worked fine - port 21 would not work for some reason

Same issue with a just purchased Extreme. Motorola Cable modem connected to WAN port, port mapping set for FTP, HTTP and VNC access, all have worked prior to the AE, but now I just get (if searching from my work Windows (ugh!) machine, the scanning torch, no file list is ever returned to me. Before it was lightning fast, only change is insertion of the AE instead of an ethernet cable from the cable modem to the PBook. Like I say, HTTP and VNC don't work either, is there likely to be a single common error stopping all of these? Thanks in advance!