? , cd , disconnect , escape , exit , help , hook , quit , repeat , rz , suspend , sz , version
lifekeeper is a completely trivial program that prints an ASCII NUL character every 30 seconds. This has no effect visually, but if someone is watching the connection for activity it will see some. People using remote connections through firewalls might find it useful, as often masquerading firewalls are configured so to shut down connections that appear not to be active for some time.
zssh (Zmodem SSH) is a program for interactively transferring files to a remote machine while using the secure shell (ssh). It is intended to be a convenient alternative to scp , allowing to transfer files without having to open another session and re-authenticate oneself.
File transfer is achieved by using another tty/pty pair between the user and the local ssh process to plug either the user's tty (remote shell mode) or another process (file transfer mode) on the ssh connection.
ztelnet behaves similarly to zssh, except telnet is used instead of ssh. It is equivalent to 'zssh -s "telnet -8 -E"'
Files are transferred through the zmodem protocol, using the rz and sz commands.
zssh behaves as an usual ssh session until the escape sequence is depressed ( currently ^@ ), which enables file transfer mode. A new prompt is then displayed, and commands can be executed locally to initiate file transfers (among other things). It roughly behaves as a local shell featuring line edition, history and completion (thanks to libreadline), globbing, and escape characters ( " ' and \ ).
The following builtins are handled by zssh itself:
? , cd , disconnect , escape , exit , help , hook , quit , repeat , rz , suspend , sz , version
If file transfer is initiated but never completes, chances are the pty/tty on one of the systems are not 8-bit clean. (Linux is 8-bit clean, NetBSD is not). Using the -e (escape) option of rz should solve this problem.
doesn't work even if I zssh to my localhost. rz -e won't help.
tong@xpt:~$ rz -e ... waiting to receive.**B0100000063f694 zssh@xpt > cd tmp zssh@xpt > dir 11getlog.lst example_raw.lyx tsun zssh@xpt > sz example_raw.lyx
— that's it, waited there indefinitely.
Date: Tue, 12 Jan 1999 01:18:41 GMT
> Some earlier posts indicated that it was possible to > use zmodem to transfer files under an ssh connection. > I have played around with this for a while and I > can't figure out the key sequences to start the > receive operation.
The secret of 'rz':
destination computer -- Unix box source computer -- Win95 machine running TeraTermPro with ttsh
dba1% rz rz ready. Type "sz file ..." to your modem program ...rz 3.48 01-27-98 finished.
The above is from a actual rz session. I typed 'rz' in the unix shell to start it listening for zmodem sequences. Then on the win95 end, I had ttermPro send over a file with the zmodem protocol. The file transferred fine. In going between two unix machines, on the source computer you would type "sz file …" as the 'rz' prompt indicates. Part of the secret is starting 'rz' on the receiver before trying to do the 'sz' end.
Rich
>Part of the secret >is starting 'rz' on the receiver before trying to do the 'sz' end.
Actually, this shouldn't be the case. With a properly working sz program, the first thing sz does is to send "rz" to the remote. That should start the receiver automatically. Thus, if things are properly configured, there's no need to start the rz program manually as suggested above.
Perhaps you don't have a rz receiver, or maybe it's not in your path. Try starting it manually with by typing "rz". If that dosen't work, try /usr/local/bin/rz or some such. If you can't start it manually with "rz", it ain't gonna start automatically.
Another common problem is tty cooking that gets in the way of sz. Fight that problem with "sz -e" to escape control characters. When doing sz over telnet, this is often necessary. I wouldn't be suprised if ssh works the same way.
Chris Nadovich
I just checked it out (transferring without doing an explicit rz on the receiver), and it works as you say it should. Thanks for the info.
Rich
>the sending with sz, but I can't get control to >start the rz. What is the secret?
It would be nice if ssh had a ~| command that would tie stdin/stdout of the command to the ssh stream.
What I do is I grabbed ztelnet from the net somewhere (probably out of the linux archive on sunsite; any search should probably turn it up). I then "ztelnet localhost" (private machine at home). From that telnet session, I ssh to where I want to go, fire up sz on that end, hit c-] on local end, type rz, and away I go.
Of course I'm assuming here that you are looking for a unix-to-unix solution. You didn't specify otherwise, and that's where my experience is.
mrc
>type rz, and away I go.
Really slick. Works perfectly, thanks.
Telnet with ZMODEM up/download capability
ztelnet is telnet hack(from BSD source) to do zmodem transfer. It is useful for zmodem transfer in BBS. You can upload and download file using the Zmodem sz/rz command from within telnet. By default, the 8-bit transfer option(-8) is implied. Thanks to Pyun, Yong-Hun and Carl Mascott for the FreeBSD patches.