NAS326, FTP behind NAT

mitetto

Hello, this NAS resides behind NAT and I'm trying to do ftp backups using Cobian Reflector. The ISP agreed to forward ports 21, 5001-5004.Test connection is OK, but real jobs not working (most of the times) active or passive. I've read about ForcePassiveIP and i've been wondering is there a way to apply this since there is no /etc/pureftpd.

Thanks

Mijzelf

Did you set the data ports on the NAS to 5001-5004?

mitetto

Yes I did. Using winscp and windows ftp command with active FTP connection is OK but not with Cobian.

Mijzelf

I don't know Cobian. Does it provide logs? Is it possible that the NAS and the Cobian client are in different networks using the same subnet?

mitetto

Cobian logs are kinda scarce. Yes the NAS and the client are on different networks but use the same (192.168.1.0/24) network. Later I'll post pictures of cobian settings

@Mijzelf thanks for your swift replies.

Mijzelf

Yes the NAS and the client are on different networks but use the same (192.168.1.0/24) network

That can be a problem. In active mode the FTP server opens a port, and tells the client to connect to IP/port. As the server is in a private network, and doesn't know it's public address, it will use it's private address. Most, and probably all clients will ignore the IP when it's in an unrouterable range, and use the public address they used to reach to the server initially. But when it's in the same subnet it's not unrouterable.

A solution could be to change the advertized IP address of the server. The Tweaks package has an option for that. That works only if you have a static public IP address, or use a dyndns server. And a problem can be that you can't use the FTP server from the internal network if the router doesn't support loopback.