Marc Elliot Hall wrote:
On Fri, Jul 21, 2006 at 08:50:46AM -0700, Ken Herron wrote:
Ken Herron wrote:
Also, I've read that to port-forward an FTP server, the firewall has
to watch the FTP command channel, open holes for each data connection,
and maybe even modify some packets.
Okay, see <http://www.ncftp.com/ncftpd/doc/misc/ftp_and_firewalls.html>,
in particular "Why PORT Poses Problems for Routing Devices" and
"Problems when the FTP Server is Listening on a Non-Standard Port
Number". Now imagine your netgear thinks it's dealing with FTP and is
doing that to your ssh sessions.
Not that I'm disagreeing with you about the router's possible confusion,
but I'm not running an FTP server. ;-)
I never said you were. You're running ssh over port 21, which is
normally the ftp command channel port. So the router might be applying
its ftp forwarding support to your ssh traffic and scrambling it in the
process.
I'll investigate further in this direction; however I don't think my
appliance is nearly smart enough to rewrite packet headers. It just
accepts inbound traffic on designated ports and passes it through
unmodified to the same port on a specified host on my network.
Netgear routers can port-forward ftp. If you'd read the link above,
you'll see that dumb packet forwarding isn't sufficient to port-forward
ftp. So netgear routers almost certainly have logic to do the protocol
monitoring and packet rewriting described.
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