Error while connecting to FTP if FTP location is behind a router (other FTP clients work fine)
I'm trying to get simple backup to FTP location work, but gives Error.
What happens when adding new FTP location:
- Acronis recognizes FTP server address and port, prompts for login credentials. Ok so far.
- Acronis accepts login credentials and saves them. Ok so far.
- Acronis shows empty list with label "There are no items to show in this view." or nothing at all.
- When pressed OK, a new window with a progress bar appears, saying "Checking vault..."
- After 10-30 seconds an error message appears "Error: The vault you have selected is unavailable at the moment. Select another vault."
FTP location is behind a router.
- All port numbers on a router are properly forwarded on a router and configured in firewall (tested with FileZilla).
- Acrons fails in both active and passive modes ftp:// and aftp:// (FileZilla Client connects fine to both).
- Acrons fails to connect to both IIS FTP server and FileZilla FTP server on the same machine (FileZilla Client connects fine to both).
- If the same FTP location is accessed from LAN via 192.168.x.x, Acronis connects fine. At this point I'm sure it can't be server's firewall and it can't be incompatibility with the FTP server.
- Even if the server is exposed to internet without router's firewall (as DMZ exposed host), Acronis still fails. Again, FileZilla client connects perfectly.
My conclusion is: This must be a bug in your product. Please investigate this and fix, we are unable to perform backups.
Igor,
Log file attached. If you need access to our server for testing purposes, let me know.
Slava
Hello Slava,
Sorry for the late reply.
From the log file, it seems that the server is rejecting the connection with the following message:
"425 [this is FTP error 425] Rejected data connection for transfer of "/", IP addresses of control and data connection do not match"
The error is clear enough, but it seems very strange that the two don't match. I would check the server-side logs and look at what packets are sent on which ports from the client machines (maybe the two connections are forwarded differently?).
Hi Igor,
In this situation Acronis Backup opens the FTP connection by domain name, which is a public (WAN) IP of the modem. Then AB tries to open the data channel on a LOCAL IP.
<- 227 Entering Passive Mode (192,168,2,37,235,17) ... <- 425 Rejected data connection for transfer of "/", IP addresses of control and data connection do not match
Which ofcourse is different and is (and should be) denied if within LAN. When connection is initiated from outside LAN it's even worse. It's not even the same FTP server anymore.
Explanation: The server sends a local IP address for Passive mode because it's the only IP address it knows. The server cannot be aware of the port forwarding of the incoming connections and the public IP addresses of the routers and modems.
When I connect with FileZilla, I find the same response from the server, but FileZilla doesn't use the local IP address. FileZilla client log:
Response: 227 Entering Passive Mode (192,168,2,37,235,26) Status: Server sent passive reply with unroutable address. Using server address instead.
Acronis Backup should never use IP address for data channel that is different from IP of the connection channel.
Hello Slava,
Thank you for your feedback. We will take this into account for future updates.
In the meantime, would it be possible to add the FTP location by the correct local IP in our product interface?
Igor,
I'm glad to help.
This is possible for machines within the same LAN as FTP server. Machines that connect to FTP server from outside LAN cannot backup without relying on third party software for mounting FTP locations as virtual local disks.
Slava