How to get file to a host when all you have is a serial console?

Question

When all you have is a serial console (say via telnet through a terminal server), what methods can be used to transfer files in/out of a host?

Cut/paste works for the small/printable stuff and I've played with a combination of uuencode/uudecode (with gzip) handle the unprintable but it's all very limiting.

Answer 1

have you tried minicom file transfer?

Answer 2

Most of the serial console programs (minicom, HyperTerm, VanDyke CRT...) you'll use on the other end of the connection will have Zmodem support, and most Linux boxes have the lrzsz package installed on them already. If not, lrzsz is small enough that you could bootstrap the process with one of the other recommended methods. You could ASCII-upload the sources, either as C text files, or a uuencoded tarball.

Once you have Zmodem on both ends, just type rz to start the receive on the Linux box.

One of the nice things about Zmodem, relative to other alternatives mentioned like nc or kermit, is that it sends out a unique string that the serial console program on the other end recognizes as its cue to start a Zmodem send. You usually get a file picker dialog at this point, letting you choose the file(s) to upload.

Other nice things about Zmodem are the ability to transfer multiple files at once, automatic resume if a transfer aborts, etc.

Answer 3

Don't know if this would work if all you had was a serial console, but if you have network access at all, then you could use nc(1) to copy files using TCP/IP.

# WARNING: Depending on your setup, this could make your system unbootable
root@destination-box.local # nc -l 8675 | dd of=/dev/sda1
root@source-box.local # dd if=/dev/sdb1 | nc destination-box.local 8675

In the above example, I cloned sdb1 from a source box to sda1 of the destination box. My choice of 8675 for a TCP port number was arbitrary; you could use any port you have access to. And it doesn't have to be a device; it can be any file.

kevin@destination-box.local $ nc -l 12345 >> ~/.ssh/authorized_keys
kevin@source-box.local $ cat ~/.ssh/id_rsa.pub | nc destination-box.local 12345

In the second example, I copied my rsa public key(~/.ssh/id_rsa.pub) and added it to the authorized keys file for the target host.

Answer 4

I would use kermit, the grandparent of filetransfer programs. We used that already long before there was Linux.