FTP-Access with double NAT?

[Thedog]

Helo,

This one is a bit tricky for me. I have a client that previously had their own ISP connection in their office and I set up a NAS with FTP that they been working with. Now they have moved to a shared office with a network which I do not control.

I have set up a router with a static IP (which is an local IP on that network) and the network admin has set up a port forward from an external ip with port 59010 to my local router with port 21, so the idea is that

1. Someone connects to an ftp with external ip:59010
2. port forward transfers you to internal ip of the router with port 21

The problem is that it resolves, filezilla says the following:

Status: Conecting to EXTERNAL IP:59010...
Status: Connection established, waiting for welcome message...
Svar: 220 INTERNAL IP FTP server ready
Kommando: USER admin
Svar: 331 Password required for admin
Kommando: PASS *************
Svar: 230 User admin logged in
Kommando: SYST
Svar: 215 UNIX Type: L8
Kommando: FEAT
Svar: 211-Features:
Svar: MDTM
Svar: MFMT
Svar: TVFS
Svar: AUTH TLS
Svar: MFF modify;UNIX.group;UNIX.mode;
Svar: MLST modify*;perm*;size*;type*;unique*;UNIX.group*;UNIX.mode*;UNIX.owner*;
Svar: LANG en-US*
Svar: PBSZ
Svar: PROT
Svar: REST STREAM
Svar: SIZE
Svar: 211 End
Status: Server does not support non-ASCII-tecken.
Status: Connecting
Status: Getting directory...
Kommando: PWD
Svar: 257 "/" is the current directory
Kommando: TYPE I
Svar: 200 Type set to I
Kommando: PASV
Svar: 227 Entering Passive Mode (172,16,20,21,176,45).
Status: The server sent a passive answer which is not routable. Passive mode failed.
Kommando: PORT 83,251,100,122,213,83
Svar: 200 PORT command successful
Kommando: MLSD
Fel: The connection timed out

I did some translation from my native language but hopefully you understand the log. I have tried both active mode and passive mode etc. At the moment the only configuration I've done in the local router is to turn off the firewall and open port 21 for the local NAS. I tried to turn off NAT in my router but then I got no contact what so ever from the outside and machines could not get access to the Internet.

 

[Thedog]

Btw.

Svar: Answer
Fel: Error
Kommando: Command

 

[YeOldeStonecat]

Try passive mode was my only suggestion so far...been so long since I've played with FTP....as it's been replaced with more current file sharing methods now.

Does the router you have allow sticking an internal IP in a DMZ? That was you're sorta doing a 1:1 NAT of the FTP box.

 

[Markverhyden]

Double NAT'ing is a big problem. But if you cannot do anything about it just have to make it work.

FTP actually uses two ports, C&C on 21 and Data on 20. I would try having the ISP router port forward port 20 to your port 20.

https://enterprisedt.com/products/edtftpjssl/doc/manual/html/howtoftpthroughafilewall.html

 

[Thedog]

Double NAT'ing is a big problem. But if you cannot do anything about it just have to make it work.

FTP actually uses two ports, C&C on 21 and Data on 20. I would try having the ISP router port forward port 20 to your port 20.

https://enterprisedt.com/products/edtftpjssl/doc/manual/html/howtoftpthroughafilewall.html

Thanks for the link, unfortunally the NAS is quite simple in terms of configuration, port 21 is default and cannot be changed.

Anyone have a suggestion on software that would work similiar to dropbox/google drive but only store files on a server (and clients), basically using Dropbox but not their servers. Any good software like that available that someone can recommend?

 

[Markverhyden]

Thanks for the link, unfortunally the NAS is quite simple in terms of configuration, port 21 is default and cannot be changed.

Anyone have a suggestion on software that would work similiar to dropbox/google drive but only store files on a server (and clients), basically using Dropbox but not their servers. Any good software like that available that someone can recommend?

Pertino.

Write up I did some time ago.

http://www.theforcefield.net/forums/index.php?topic=7976.0