PORT command returns internal IP

[zeroabYss]

Greets:

This topic got kind of cluttered and then abandoned in a another thread -- hopefully re-entering it in a more clear & concise manner will help find the answer.

I run a FTP Server on a non-standard port behind a Linksys Firewall Router (1-Port version). Port-Forwarding is enabled to the one non-standard port, and the FTP works great for most people.

The problem arises when people behind firewalls (or possibly just routers) try to log in. They successfully log in but cannot recieve a directory listing. I have isolated the problem to this: When a user not behind a router/firewall logs in PORT returns their IP and then the port number in this format (x,x,x,x,p,p) and the LIST gives the the directory listing; however, when users behind routers/firewalls log in the PORT command returns my machines internal IP (192,168,1,100,p,p) and the LIST command fails on error code 426 Cannot Retrieve. - or when using Passive Mode: 426 Cannot Retrieve.Aborting).

This is what I have tried based on previous suggestions to fix the problem:

1) Told clients to use Passive Mode... PASV returns my internal IP too.
2) Opened FTP-Data Port (port 20)
3) Had clients use different FTP Clients (so far, IE5, IE5.5, Netscape 4.x, LeechFTP, and FlexFXP I believe it is called)
4) Tried running the server on 10 different server applications.

Also, this not from one OS - I have had users from Win95/98/2000/UNIX use the server. My next test is running the server on my Win2000 machine... (haven't been able to test it yet, but I don't have high hopes)

None of these alone or together have resolved the problem.

Please, if you have any thoughts -- or even better experience with this problem, reply

Thank you in advance for you help.

 

[zeroabYss]

anyone?

 

[miketvr]

Well, it happens to me often too. I use ip masqing at home, and I often have problems connection to non-standard port FTP sites from anything on my private lan. I just gave up and installed squid on the linux machine, and use it as an FTP proxy.

 

[Scarpozzi]

What FTP server are you running? Also, make sure the people logging in are using actual FTP software and not MSIE. IE isn't a true FTP program obviously so it doesn't do as good as a program such as Cute. Finally, I would suggest trying ServU if you aren't running that for your server. I'm running the same thing and with ServU and Cute, I've had no problems. Just some thoughts...

 

[miketvr]

for me on the client side, ive had problems with cuteftp, BP ftp and wsftp. i connect to many server types, usually wuftpd.

 

[zeroabYss]

Currently I prefer G6... but as I said I have tested it with about 10 FTP servers: G6, Serv-U, FXP, Broker, a whole bunch of odd names.

As for clients used to log in: Leech, and FlashFXP I suppose are the only true clients... but this internal ip thing really should not make a difference on the client end. After all anyone not on an internal IP can log in with anything that can do ftp

I never tried leaving it on standard port 21... next thing.

Thank you all for the thoughts/suggestions, please keep them coming-- I will try that port 21 suggestion as soon as I can get one of my friends behind afirewall to log on to ICQ.

 

[zeroabYss]

Well as much as it pisses me off, changing to port 21 fixed the problem for those behind firewalls/internal ips -- or whatever the real problem was. I would still like to know why a non-standard port could not be used, but I almost don't care anymore ... hehe

Thanks all!