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Fun with Kermit and ZMODEM over SSH

cambus.net

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Re: Fun with Kermit and ZMODEM over SSH

#41

Post by kej »

seanmceligot wrote: post #24

I still miss sz and rz when I ssh from a computer with no ssh server like nearly every windows box. If I remember right, sz = send a file from the server I'm in back to the client server. rz = receive a file from the client server. You can accomplish the with a new scp session on the client server, but it's an extra step. I use this as a helper when for building the scp command. function scppath() { echo $USER@$(host…

There's a "zssh" project that wraps an SSH session with ZModem handling, but it would be neat to see a tool like that this didn't require sz and rz installed.

[0] https://zssh.sourceforge.net/

Re: Fun with Kermit and ZMODEM over SSH

#43

Post by Lammy »

Sohcahtoa82 wrote: post #29
yjftsjthsd-h wrote: post #15

Earlier quoted context omitted.

Thanks for the laugh (but also kind of serious) - reminds me of https://xkcd.com/2221/ (what a fast floppy drive you have!)

Now I'm wondering if there's ever been emulated software that crashed because it tried to calculate a data transfer rate, but the emulator transferred the data faster than the delta in the time measuring in the emulated machine, so it divided by zero.

There's a bug like this in all versions of Windows 95, the original release of Windows 98, and all of the Nashville/Memphis beta releases in between: https://web.archive.org/web/20030819124031/https://support.m...

“The timing calibration code in the Network Driver Interface Specification (NDIS) driver causes a divide by zero if the CPU runs at 2.2 GHz or faster. This problem does not occur with CPUs that run at 2.1 GHz or slower.”

It was patched for Windows 98 (312108USA8.EXE), but '95 was left without an official fix due to its age: http://lonecrusader.x10host.com/fix95cpu.html

Re: Fun with Kermit and ZMODEM over SSH

#44

Post by geocrasher »

YesThatTom2 wrote: post #26

sz and rz! Such good memories.

I came here to say this. I still think rz and sz should be supported everywhere. Even now, I can't tell you how many times I wish I could grab a file straight form the terminal. We lost something when we stopped using zmodem. (and for the record, yes, I do know about all the other things that aren't saving a file direct from the terminal)

Re: Fun with Kermit and ZMODEM over SSH

#45

Post by devilbunny »

bm3719 wrote: post #11

My only source of internet in undergrad was dialing into my university's modem pool and getting a shell on the main server (a DEC Alpha running OSF/1). Browsing the web was done through lynx. That worked fine but every now and then, a site would have some inline image that I'd want to see, so I'd view source to get the img URL and then download that to /tmp and transfer the file to my local machine via zmodem. Usuall…

One summer, I had access to a local university's Ultrix machine (on 4.2 BSD) via dialup. The connection was 7E1, so Zmodem was out.

But I could uuencode into a big buffer on my terminal program and uudecode locally.

Re: Fun with Kermit and ZMODEM over SSH

#46

Post by distantsounds »

lrzsz is one of the first packages i install when configuring a new system. being able to send and receive files between remote and local without needing a separate ssh session is such a time saver. it's really fast as well. i do wonder if anyone has developed something more modern to make it even more performant?

Re: Fun with Kermit and ZMODEM over SSH

#47

Post by themodelplumber »

devilbunny wrote: post #38
themodelplumber wrote: post #21

Earlier quoted context omitted.

Jumping from Kermit to ZModem was quite a revelation for this Muppets fan. I was so sad to find I'd been needlessly reducing my download speed just by going with the fuzzy green frog, when presented with all of the different download options.

You probably didn't have Kermit configured correctly; most of us didn't. When someone finally showed me how to set the options (which default to reliable-but-godawfully-slow) for much higher speed transmission (bigger segments, sliding windows for ACK, maybe a few other things?), it was entirely comparable to Zmodem.

That's pretty funny. I don't remember ever coming across configs for Kermit or other protocols, just the [K]ermit | [Z]modem -type options on the front end of whatever clients I was trying out.

I wonder why more than one client would default to such comparatively-lame settings for Kermit though.

Re: Fun with Kermit and ZMODEM over SSH

#49

Post by svennek »

distantsounds wrote: post #46

lrzsz is one of the first packages i install when configuring a new system. being able to send and receive files between remote and local without needing a separate ssh session is such a time saver. it's really fast as well. i do wonder if anyone has developed something more modern to make it even more performant?

how do you do that, also through qodem or ?

Re: Fun with Kermit and ZMODEM over SSH

#50

Post by kevin_thibedeau »

jhallenworld wrote: post #37
glonq wrote: post #10

Last year we implemented "ymodem over BLE" for reasons that are complicated and possibly stupid. It felt familiar but strange and wrong to do such a thing. Worked great though.

I still use these protocols for embedded systems. There is almost always a CLI on a UART, so one should be able to transfer files. Ymodem is simpler and smaller than Zmodem, but we've used both. I've used Zmodem at 921600 baud, but it needs fairly large buffers (for a UART) to work. One of the big advantages is that TeraTerm for Windows exists, and supports xyzmodem. It means that I often don't have to write any host…

A former employer still insists on using Xmodem-1K even though Ymodem is almost the same and provides so many quality of life improvements with the header block. It was endlessly annoying to have to manually tell the receiving end the file size and name when a simple upgrade would obviate the need.
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