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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

#21

Post by themodelplumber »

sedatk wrote: post #12

Thankfully, ZModem existed. I’d never been able to use Kermit successfully back in the days, always had trouble with it. I even had more success with XModem.

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.

Re: Fun with Kermit and ZMODEM over SSH

#23

Post by jabbany »

jebr224 wrote: post #22

Kermit is still used in the embedded space, on modern platforms specifically for uboot. zmodem can also be used in embedded spaces to retrieve files if the only interface is a serial port.

This! I still recall using zmodem not that long ago for this exact purpose of sending firmware blobs over just a serial connection.

Re: Fun with Kermit and ZMODEM over SSH

#24

Post by seanmceligot »

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 $USER@$(hostname).$(dnsdomainname):$(realpath $1) ]

Re: Fun with Kermit and ZMODEM over SSH

#25

Post by stuff4ben »

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…

LOL!! I thought I was the only person who did this. Back in the mid-90's I did the same thing. One day I was feeling a bit randy and decided to visit a certain centerfold magazine website and download some images that way.

Re: Fun with Kermit and ZMODEM over SSH

#27

Post by myself248 »

themodelplumber wrote: post #21
sedatk wrote: post #12

Thankfully, ZModem existed. I’d never been able to use Kermit successfully back in the days, always had trouble with it. I even had more success with XModem.

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.

What gets me is that ZModem-Resume had effective continuation of failed transfers _decades_ before HTTP got it right. The early days of the web drove me bonkers, having to start over with a long file that failed in the middle.

Re: Fun with Kermit and ZMODEM over SSH

#29

Post by Sohcahtoa82 »

yjftsjthsd-h wrote: post #15
jerf wrote: post #4

Hello! Thank you for starting me up! I'm the Kermit protocol and I'm happy to hel... wait, you want to transfer what file? What the hell is a giga byte? Well, man, OK, you're the user so you know best, but man, this is going to take like, days man, settle in, here we gooo ooooooo whooooooo OOOOOOOOO AAAAAAAAAAAAAAA !!!!!!!!!!1!! qcjqrjrcorRC!!! WHAT THE HECK WAS THAT? Did I just do megabytes per second ? Holy shit. A…

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.

Re: Fun with Kermit and ZMODEM over SSH

#30

Post by spudlyo »

At my last job, I worked in the PCI cardholder data environment, and we were very careful to limit egress from our systems in order to make it hard to exfiltrate data in the unlikely event of a breach. I remember thinking, if I were a wily hacker and I managed to pop a shell on one of these hosts, I would not be deterred by network egress roadblocks. I'd figure out a way to get `sz` on to a host and exfiltrate data to my heart's content with ZMODEM like we did back in the day.

Looks like it's still quite possible, I wonder if our network monitoring tools would have noticed gigabytes of data flowing out of the network that way.

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