Re: SFTP Limited Availability

Chris Braster wrote on 11/06/2006 01:22:42 PM:

> At my location we have two internal networks.  I have installed
> OpenSSH 4.4 on a server on one of those networks and the only change
> I made was for it to use port 21 instead of port 22, since port 21
> was available and getting ports opened here is a production in
> itself.  If I SFTP to that server from a computer on that same
> network, it works fine.  If I attempt to SFTP to that server from a
> computer on the other network, I get the following error:
>
> Using SSH Protocol version 2. (it sits at this line for quite a bit
> of time, then these errors appear.)
>
> Network error: Connection reset by peer
> Unable to initialize SFTP: '8 square boxes here then' t (sftp not
enabled?)
> Can't establish connection --> domainnamehere:21 @ date/time here (122-1)
>
> Any ideas?
>
> Thanks,
> Chris

My guess is that the firewall on your client network is inspecting and
modifying the port 21 traffic so that PORT commands in the FTP traffic will
continue to work in a NATted environment.  It's seeing SSH protocol traffic
instead of FTP traffic.  It gets confused and blocks the traffic.

Even though port 21 is "open", this doesn't always mean that you can use it
for a protocol other than FTP.