User (Old forums)MemberJanuary 25, 2005 at 9:18 amPost count: 23064
We are using 2 windows 2003 servers (Production & Development, both rentals). I developed a VB 6.0 program which uses XceedFTP library 1.1 (version 22.214.171.124) to download files from our client FTP server. After deploying my program on both servers all works very nice on Development server but it fails on production. It connects to the client FTP server successfully, but as soon as I request LIST of files it hangs for minte or two and then gives me this error:
220-FTPSERVE IBM VM V2R4 at XXX.XXXXXXXX.XXX, 22:41:56 EST MONDAY 01/24/05
220 Connection will close if idle for more than 5 minutes.
331 Send password please.
230 AISDATA logged in; working directory = AISDATA 191
257 “AISDATA.191” is working directory
Successfully connected to: XXX.XXXXXXXX.XXX
200 Representation type is ASCII.
An error occured while receiving a reply line from the FTP server.
I know this has nothing to do with XceedFTP Library component, the problem is with settings on our Production server. At this point I have no idea were to look in order to fix the problem so if anybody has any suggestions/advice please let me now.
Thanks a lot.
Imported from legacy forums. Posted by jaryr (had 4165 views)User (Old forums)MemberJanuary 25, 2005 at 9:57 amPost count: 23064
By working in PORT mode, you require the client machine (and the LAN if connecting outside) to accept the incoming connection at every port number that will be used (the last two digits of the PORT command).
Normally, a local machine in a secured LAN does not need to prevent incoming connections, thus does not have a firewall blocking such accesses. But since Windows XP SP2 and Windows 2003 SP1, the Windows Firewall is indeed blocking incoming connections by default.
Now, starting from this point, I’m less familiar with all the required notions, but I’ll try to point you to the correct answers.
On a LAN, the external entry point (the machine that allows access to the Internet) is often (always?) running a proxy application that is managing the bridge between internal computers with local IPs, and external computers on the Internet. When a local machine, who’s IP may be something like 192.168.100.147, connects to an external IP like 126.96.36.199, that external computer sees the external LAN IP, not that local computer IP. Furthermore, when that local computer asks this server to connect to port 7765 on IP 192.168.100.147, if that request would arrive as is to the server, it wouldn’t know what to do with this IP. Fortunately, the proxy on this LAN recognizes the exchange of FTP commands and replies. Everytime it sees a PORT command going out, it starts listening on its external IP and replaces “PORT 192,168,100,147,30,85” with its own IP and PORT. When the server connects to the proxy’s listening address, the proxy connects to the local machine and makes the bridge for the time of the connection. What is even more important is that this proxy is responsible for opening this port through the external firewall.
On Windows Server 20003, ISA Server is the “proxy server” (among other things). I don’t know how to configure it. I don’t know how it works. But I have a feeling you need to activate FTP support within ISA Server.
Imported from legacy forums. Posted by Martin (had 247 views)
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