Reverse SCP over SSH connection

scpssh

I pretty often need some file from some server when I'm on my laptop. But if I don't know where that file is, I have to ssh into the server, look around, exit, and then scp server:file .. If I'm working with my desktop and my server, both of which have static IPs, I can just SCP the file in reverse (scp desktop:~ file), but I can't do that for my laptop. Is there any nice way to SCP a file backwards over an SSH connection? So that the computer I connect to with SSH sends a file backwards to the client?

Best Answer

This would be a lot easier with SFTP, which is an extension to SSH that supports more complex file operations than SCP. Virtually all modern Unix and Linux distributions support it. To use it, just run this command to connect to the server:

sftp server

Then you can use the ls and cd commands to browse around and find the file you're looking for. Once you've found it, use the get command to download it. For instance, to download file.txt in your current working directory on the server to your current working directory on your local machine, just run:

get file.txt

To download /home/pavpanchekha/textfiles/file.txt on the server to ~/textfiles/ on your local machine, instead run:

get /home/pavpanchekha/textfiles/file.txt ~/textfiles/

Conversely, you can also upload files in this manner. To upload file.txt from your local current working directory to the current working directory of the server, type:

put file.txt

You can also use full paths for each like you can with get:

put ~/textfiles/file.txt /home/pavpanchekha/textfiles/file.txt

For a full list of available SFTP commands, just run help at the sftp> prompt.

Related Solutions

SSH Configuration – Can SSH Be Used Without SCP?

Apparently, it is possible (according to post #3 at that link). The trick is in the authorized_keys file format. There are several options that allow the server to restrict SSH features based on what key was used to authenticate. The "command=" option allows the server administrator to attach a restriction on the public key -- something like

"any incoming connections that authenticate with this key will execute this command, regardless of what command might have been requested by the user".

It might prevent the execution of standard SCP and SFTP, but if it provides an interactive shell there's probably a way around it:

$ ssh user@host 'cat /some/where/whatiwant.txt' > igotit.txt

Copy files over SSH without using SCP

You can use a FUSE application to mount remote files to the local filesystem. Then you can work on the files directly. When you change them, they will be changed on the remote end automatically.

First make sure you have the fuse kernel module loaded or built-in.

Then you can use either sshfs, which is a standalone application:

sshfs user@hostname: mountpoint # to mount to mountpoint
fusermount -u mountpoint # to unmount

Alternatively, you can use GVFS. If your're in a desktop, just type this into the file manager (or use gvfs-mount in command line):

sftp://user@hostname/

And the filesystem will be mounted to

$HOME/.gvfs/sftp for user on hostname

If however you're not in a desktop, you'll have to start a D-Bus session before you can use gvfs-mount:

$ dbus-launch 
No protocol specified
DBUS_SESSION_BUS_ADDRESS=XXXXXX
DBUS_SESSION_BUS_PID=YYYY
$ export DBUS_SESSION_BUS_ADDRESS=XXXXXX # copy value from above

You can automate the above by a shell script which you source (!).

Best Answer

Related Solutions

SSH Configuration – Can SSH Be Used Without SCP?

Copy files over SSH without using SCP

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