SSH easily copy file to local system

Question

If I'm logged in to a system via SSH, is there a way to copy a file back to my local system without firing up another terminal or screen session and doing scp or something similar or without doing SSH from the remote system back to the local system?

Answer 1

Master connection

It's easiest if you plan in advance.

Open a master connection the first time. For subsequent connections, route slave connections through the existing master connection. In your ~/.ssh/config, set up connection sharing to happen automatically:

ControlMaster auto
ControlPath ~/.ssh/control:%h:%p:%r

If you start an ssh session to the same (user, port, machine) as an existing connection, the second session will be tunneled over the first. Establishing the second connection requires no new authentication and is very fast.

So while you have your active connection, you can quickly:

• copy a file with scp or rsync;
• mount a remote filesystem with sshfs.

  Forwarding

On an existing connection, you can establish a reverse ssh tunnel. On the ssh command line, create a remote forwarding by passing -R 22042:localhost:22 where 22042 is a randomly chosen number that's different from any other port number on the remote machine. Then ssh -p 22042 localhost on the remote machine connects you back to the source machine; you can use scp -P 22042 foo localhost: to copy files.

You can automate this further with RemoteForward 22042 localhost:22. The problem with this is that if you connect to the same computer with multiple instances of ssh, or if someone else is using the port, you don't get the forwarding.

If you haven't enabled a remote forwarding from the start, you can do it on an existing ssh session. Type Enter ~C Enter -R 22042:localhost:22 Enter. See “Escape characters” in the manual for more information.

There is also some interesting information in this Server Fault thread.

Answer 2

SSH does support a few commands, via the ~ escape character:

$ ~?
Supported escape sequences:
  ~.  - terminate connection (and any multiplexed sessions)
  ~B  - send a BREAK to the remote system
  ~C  - open a command line
  ~R  - Request rekey (SSH protocol 2 only)
  ~^Z - suspend ssh
  ~#  - list forwarded connections
  ~&  - background ssh (when waiting for connections to terminate)
  ~?  - this message
  ~~  - send the escape character by typing it twice
(Note that escapes are only recognized immediately after newline.)

$ ~C
ssh> help
Commands:
      -L[bind_address:]port:host:hostport    Request local forward
      -R[bind_address:]port:host:hostport    Request remote forward
      -D[bind_address:]port                  Request dynamic forward
      -KR[bind_address:]port                 Cancel remote forward
      !args                                  Execute local command

The !args seems to be closest to what you want. Note that you'll need to have PermitLocalCommand enabled in your /etc/ssh_config file in order for the ~C commands to work (see man ssh_config).

You can re-use the same ssh session if you set up a ControlMaster in ssh_config. If you do this:

$ ~C
ssh> !scp file user@myserver:

you've technically never left the ssh session, and don't need to re-authenticate. Probably more complicated than you'd like, but I can't think of another easy way.

Answer 3

Those are all very complicated methods.
You can mount the remote file system on your local machine with sshfs:

mkdir -p /mnt/sshfs

root@IS1300:~# sshfs 192.168.1.2:/ /mnt/sshfs
root@IS1300:~# umount /mnt/sshfs

Then you can copy paste the file with nautilus, gnome, konqueror, dolphin, bash or whatever.

Answer 4

An even simpler approach: Open Filezilla (or your favorite ftp browser), open an ssh connection to the same site, find the file and drag it across to your local file structure. If you're new to Filezilla, use the "site manager" feature to reconnect fast next time.

Yes, I know this is obvious to most of you (and not precisely on point), but some (like me) who found this thread searching for a terminal-only solution may have overlooked the obvious.

Answer 5

This isn't possible in the "same session", but to make it easier to open another session for copying, you can either use SSH keys or the "Control Master" feature.

Answer 6

• Use ssh-xfer, a modified ssh-agent which effectively overloads an existing ssh side-channel for file-transfer use.
• Use zssh, which is effectively zmodem over ssh. If you've ever used rzsz this will seem very familiar.
• Reverse (-R, for remote-to-local) or forward (-L, for local-to-remote) ports to run file transfers over, assuming you have some file-transferring daemon listening on the other end.

But none of these are really needed, IMO. The SSH protocol supports multiple channels on a single connection, and the OpenSSH client supports multiplexing. Assuming you have ControlMaster and ControlPath set up (ControlPersist is useful too),

  # first connection
$ ssh remote

  # will multiplex over the same connection the original ssh opened
$ sftp remote

Answer 7

There is an explanation of how to get the reverse tunnel automatically set up

I have not tried this myself yet, but have kept it in my bookmarks for trying it out at some point in the future.

Answer 8

Use "!" to convert the file to a ASCII-representation of your file (e.g. uuencode). Then use ! cat uuencode.dat >target.dat. After that use uudecode on the target side.