Problems connecting to home server

[SOLE2000]

I have a server at home which I connect to remotely when I'm on the road. My portable computer is running Win XP with SP2 and I use either IE or Flash FXP to connect, and my home (server) computer is also running Win XP with SP2 and the server software I've tried is either Bulletproof FTP Server or ServU Corporate. My IP address for my server is dynamic.

The odd thing that happens is that I remotely control the computer using Symantec's PC anywhere and it connects in an instant, however, when I try to access the computer using FTP, the connection just hangs. I suspect it might have to do with my server computer's security software (Norton Systemworks 2005).

I've established the "Permit" funcion in the Program Rules section of the Norton Antivirus section, but it still does nothing. Any ideas what else could be causing the connection problems?

Thanks!

[Tuttle]

FTP is a slightly unusual protocol in that it uses multiple simultaneous connections. The one which traditionally involves port 21 is the control connection; that only carries commands and responses. Then, for each data transfer (including the directory list that just about every FTP client requests by default), a separate data connection is established.

There are two modes for FTP. Active FTP is where the server connects back to the client, and passive (or PASV) FTP is where the client creates a second connection to the server. In both cases, you can't really predict the ports which will be used, and the software on whichever machine is receiving that data connection (ie client for active, server for passive) needs to know its own public IP address (which is difficult behind NAT).

Any firewalls or NAT devices in your data path need to deal with all that weirdness.


Unless you need FTP specifically, it's often easier to look at other transfer mechanisms. SFTP (file transfers through SSH) is often good, and PC Anywhere probably includes a file transfer mechanism of its own.

[SOLE2000]

Hey all... it turns out that the problem is with my laptop computer and not the server... I'm trying to access any ftp and no good. I've tried from different networks (office, home, public) and they all freeze, both using XP and Flash FXP.

Again, the laptop is using windows XP Pro with SP2, and security software is Norton Systemworks 2005 and I also have System Mechanic Professional 6 installed. The antivirus and firewall software is from Norton (I have placed under "permit" Flash FXP under the program control options in the Antivirus options) and Systemworks I use mainly for general computer cleanup and defragging.

Again, any and all help is incredibly welcome!!

[Tuttle]

Make sure passive (or PASV) mode is turned on in your FTP software and see if that makes a difference.

[SOLE2000]

Hey tuttle... I just saw now that I'm able to access FTP sites again on my laptop. The only difference I'm seeing with a couple of days ago is that I'm on the road and the internet access I've purchased in the hotel is with a public IP address, while the other ones is a private IP. Would this have anything to do with the access?

[Tuttle]

Yeah. Remember what I said in that first post -- whichever device is receiving the data connection (in the default, active mode FTP, that's you) needs to know its own public IP address.

If you're behind a NAT device with a private IP and your FTP client doesn't know about it, the FTP client tells the server to connect to its private IP address, which fails miserably. That's why passive mode generally fixes it -- the only time that has issues is when you get both ends behind NAT devices.