Forward Port 20 on Server

I am trying to use ftp in a tunnel using PuTTY on a Windows client. I
know it is problematic, but I have been reading that if I don't use
passive mode, and forward port 20 on the server to 22, it might work.

I can easily configure PuTTY to forward ports, but how do I get a linux
server (behind a cable router) to forward 20 to 22?

I am using SuSE 9.1 I don't have any firewall running, since I have the
router.

Buck Turgidson wrote:
> I am trying to use ftp in a tunnel using PuTTY on a Windows client. I
> know it is problematic, but I have been reading that if I don't use
> passive mode, and forward port 20 on the server to 22, it might work.
>
> I can easily configure PuTTY to forward ports, but how do I get a linux
> server (behind a cable router) to forward 20 to 22?
>
> I am using SuSE 9.1 I don't have any firewall running, since I have the
> router.

You need to tunnel both TCP ports 20 and 21 to make FTP function.

FTP is a notoriously insecure protocol. That may be the cause
of not allowing it in your set-up.

I'd recommend to use the SSH services instead. For file transfer,
WinSCP works well under Windows.

--

Tauno Voipio
tauno voipio (at) iki fi

> You need to tunnel both TCP ports 20 and 21 to make FTP function.
>
> FTP is a notoriously insecure protocol. That may be the cause
> of not allowing it in your set-up.
>
> I'd recommend to use the SSH services instead. For file transfer,
> WinSCP works well under Windows.

I have a client that only supports FTP. I would imagine that if it is
tunnelled in ssh, it is as secure as ssh itself. I know about 21 forwarded
at the client, but I understand that 20 needs to be forwarded at the server
to 22, which I don't know how to do.

Get ssh client from ssh.com. You can do Secure FTP.

Bhaskar

Buck Turgidson wrote:
>>You need to tunnel both TCP ports 20 and 21 to make FTP function.
>>
>>FTP is a notoriously insecure protocol. That may be the cause
>>of not allowing it in your set-up.
>>
>>I'd recommend to use the SSH services instead. For file transfer,
>>WinSCP works well under Windows.
>
>
> I have a client that only supports FTP. I would imagine that if it is
> tunnelled in ssh, it is as secure as ssh itself. I know about 21 forwarded
> at the client, but I understand that 20 needs to be forwarded at the server
> to 22, which I don't know how to do.
>
>

I it is a normal FTP, TCP/20 is tunneled to TCP/20 and
TCP/21 is tunneled to TCP/21 (server ports). The client
may use ephemeral ports, if it is not expected that the
server opens a data connection to the client (active
download).

In a normal set-up, TCP port 22 is for SSH.
--

Tauno Voipio
tauno voipio (at) iki fi