FTP Passive mode + Asus RT AC68U -> Error: Server returned unroutable private IP address in PASV reply

My Cloud OS 3 Personal & Network Attached Storage My Cloud
1

Hello, I’m trying to connect to my wdmycloud with FTP passive mode, TLS and an ASUS RT AC68U router.
I think i’m routing ok, but keep getting this:

Error: Server returned unroutable private IP address in PASV reply

I understand that the FTP server is returning the private IP address and need to return the public IP address, but no clue in getting that to work, any ideas?

2443×1504 291 KB

2

Hi,

What’s the firmware version installed on your My Cloud and did you configure port forwarding for Port 21?

3

Hello @G_Rayn, I’m using 2.30.165 and yes I have configured port forwarding on port 21, in both, my router and wdmycloud device. Here are the screenshots of my actual configuration. I’m missing something in the way?
Thank you.

FTP settings:

1610×740 34.4 KB

1606×650 34.3 KB

1613×837 38.8 KB

Port Forwarding on wdmycloud:

1450×417 13.5 KB

1093×773 29.1 KB

Port forwarding on ASUS RT-AC68U:

1934×543 109 KB

4

I don´t know what to test or think at this point, I have spent 3 days in this issue. Could be NAT in my router failing? or the FTP server sending a bad internal IP instead of the external public IP? could be a double NAT issue? Any ideas in how to test this?

Thank you.

5

I’m not familiar with PASV mode, but I note your Asus port forwarding rules don’t seem to have an internal forwarding address range. Is that right?

I’m also not sure why you’ve forwarded ports 20 and 21 to port 21. Does FTP use port 20? I thought it used port 21.

Can you select the protocol to be FTP, than than TCP?

6

Hey hello, in the Asus port forwarding if I don’t specify internal port, means that the same ports are opened externally and internally. The only protocol I have is UDP or TCP ;(
I know port 20 does nothing in passive FTP, I leave it as default.
For some unknown reason to me, the FTP server is sending the internal IP for the device instead of the public IP. Maybe I’m missing something… No clue.

I have an internet modem from my ISP in bridge mode connected to the Asus router.
The IP shown by the router is a public one so I think there is no double NAT issue.
The only thing that makes me believe I’m in a double NAT situation is a test I’ve found here:
http://www.techhive.com/article/3175739/network-router/how-to-identify-and-resolve-double-nat-problems.html

One quick way that usually shows if double NAT exists is a traceroute, which allows you to ping a server or device on the internet and see the path it takes between routers and servers. Open a Command Prompt (on a Windows PC that’s connected to the internet, click on the Start menu, type “cmd,” and hit Enter) and type “tracert 8.8.8.8“ to see the traceroute to Google’s DNS server. If you see two private IP addresses listed in the first two hops then you have double NAT. If you see only one private address and the second hop shows a public address, then you’re all good.

My tests show:

1285×439 56.2 KB

If the article is real, maybe I’m behind a double NAT and that could be the problem, but I can’t tell, I have no knowledge.
As I said before, maybe is an issue in the FTP server. It’s using the default pure ftpd.

7

Is there a configuration file for pure-ftpd? I have searched the web but I only found an xml for configuration, I think there could be another file…

8

I’m still struggle with my home network setup, so take my advice with a large grain of salt, but the fact that you have a ISP modem that is capable of “bridge mode” makes me think, that yes, dbl-nat could be a problem. The 10.x.x.x ip address is also an indication (but, as I said, I struggle with all of this stuff too, so experts are welcome to correct these assumptions ; -) ) .

Your modem should allow access to configuration. Try just that 10.x.x.x IP address in your web browser and see if it brings up a web-app. If the web-app is for your ISP modem, then look to see if there an option to turn off/on DHCP. If you find it is already ON, then turn it off.

Hmm, you may want to dbl-chk that DHCP is turned ON on your ASUS router before you turn it off on you modem. (Web browser to 192.168.2.1 should bring up a control app for your router).

Hoping this helps

9

Some good stuff about 10.x.x.x networks starting at this msg in the thread today

10

Hello, my ISP modem/router is an Technicolor TC 7230, when I put it into bridge mode, no DHCP functions are allowed, and nearly no router functions also…

I have tried connecting to the 10.xx.xx.xx address in my web browser but nothing happens.

Also another test I have made, is installing Filezilla FTP Server in one local machine, connected to the same ASUS router. After playing with local firewall, passive ports and TLS certificate for the server, I can connect successfully to that FTP server, with the same single or double nat thoughts, the Filezilla server is sending the correct external IP address not like pure-ftpd server thats sending his internal IP address. And I can see the log for the FTP server in real time.

So I think this is not a NAT issue, I think there is something wrong in the config of pure-ftpd that is not sending the external address…

Another important thought (I don’t know if this is important) my routers local IP is 192.168.2.1 and the modem local IP is 192.168.100.1. This could be a issue? Remember no problems with Filezilla Server, only with pure-ftpd server in WDMyCloud.