I am fairly new to ssh and still learning it. Recently I have made a tunnel connection with an ssh host and managed to successfully transfer data/files from my machine to the server with the command: scp file.extension user#hostIP:/directory/directory.
While this was successful, I am kinda struggling to reverse it, sending data/files from the server to the client. How would one go about completing that? Do I need to make some changes to ssh_config or just CLI commands are enough?
You need to change the order:
scp user#hostIP:/directory/directory file.extension
that's accomplishing the invert operation, off course, assuming that the address is correct, the file exists and you have the necessary privileges.
Related
By terminal I am able to SSH multiple times to connect to the server:
(client--->gateway--->server1---->server2---)
But now to do it through JSch library of Java, how to go about it?
First tried portforwarding, but on terminal I am not doing that (not setting -R -L parameters in ssh).
Then I came across question How to SSH to a server behind another SSH server using JSch?, but I don't understand how to create tcp tunnel!
Port-forwarding is the best way to go.
You do not do port forwarding in the terminal, as you connect to the second section manually by typing the ssh command. While you can automate that using JSch, it is not really a reliable way to try to simulate a human being. If you want to replace the first ssh (terminal) step with JSch, for the same reason you do not want to use ssh for the second step. The accepted answer in the question you link to also discourages you from trying that. While when everything goes ok, it might work. But once any problem steps in, your will have troubles dealing with it automatically. For example, you can hardly automate host key verification for the second server.
The SSH tunnel is port forwarding. But maybe the mentioned ProxySSH (which does not seem to exists anymore) did internally without opening a local port, but used the "port forwarding" channel directly by the second session. But that's a way too complicated to implement. Stick with simple port forwarding.
For a complete example, see:
JSch multiple tunnels/jumphosts
We've brought up this topic before, but curious if anyone has any new information on this issue.
We use multiple servers that are accessed behind a "management server", so when we SSH in we have to log in there first, then from there log into our destination machine so always at least 2 SSH connections. We currently use port forwarding on the management server by using : which will take us directly through to the server of interest behind the scenes so we think we're directly ssh'ing into each one.
The issue here is that it requires specific setup, and in a scalable environment where servers can be added/removed the maintenance is cumbersome. Ideally we'd just be able to ssh into multiple machines using phpseclib and run commands.
Has anyone ran into this or have advice on a solution from the scripting level? Basically we need to ssh chain and ssh into machine 1, then machine 2 from machine 1, and run commands/interact with machine 2.
$ssh = new Net_SSH2('machine1');
$ssh->login('user', 'pass');
$ssh->setTimeout(10);
$ssh->enablePTY();
$ssh->exec('ssh machine2');
echo $ssh->read();
At this point (assuming that you're using RSA authentication and that your private key is in your ~/.ssh/id_rsa file on machine) the prompt that you get back should be of machine 2.
You could connect to a machine3 as well by doing this:
$ssh = new Net_SSH2('machine1');
$ssh->login('user', 'pass');
$ssh->setTimeout(10);
$ssh->enablePTY();
$ssh->exec('ssh machine2');
echo $ssh->read();
$ssh->exec('ssh machine3');
echo $ssh->read();
I'm working on a project that requires me to run my code on a remote Unix server, that is not available to connect to directly (you first have to log in to the "gate" node and then to this server).
What's really bad is that they disabled key authentication, so each time I need to ssh into it, I have to type in my password twice. It's really annoying and I wonder what's the best way to transfer my local modifications of source files to this server, compile and run them without having to provide those passwords so many times.
I have no sudo access to any of those servers (neither to this "gate", nor to this target server). Any ideas on how to make the whole process more efficient?
EDIT: Martin Prikryl provided a great answer below, but it's suitable for Windows and I'm on a Mac :) I guess it might be a good thing to have it documented here also for *NIX systems.
You are looking for SSH tunneling.
WinSCP SFTP client supports one-hop SSH tunneling natively.
See the Tunnel page on WinSCP Advanced Site Settings dialog.
I assume that after you transfer the file, you need to open SSH terminal to compile the file.
You may be able to make use of WinSCP Console window for that step.
Alternatively, if you need/want to use a real SSH terminal client, make use of an existing SSH tunnel, created by WinSCP, and connect with PuTTY (or any other SSH client) over it.
In the Local tunnel port of WinSCP Tunnel page, select a fixed port number (instead of the default Autoselect). In PuTTY enter "localhost" to Host Name and the selected port in Port.
(I'm the author of WinSCP)
I want to create a service that will allow me to display documents and media (think PDF and JPEG) that are stored in the filesystem of a remote server to which I connect by ssh. X11 forwarding doesn't cut it because it's too slow. Instead I want to design a protocol that will copy files from the remote system on demand, then display them.
My question is twofold:
How do I acquire a port on the remote machine? Since I may have multiple connections going, I cannot simply use a single well-known port—I will have to allocate a port dynamically.
Once I have my port, how do I communicate it to the display applications on the remote machine? SSH X11 forwarding communicates by setting the DISPLAY environment variable, and agent forwarding communicates by setting the SSH_AUTH_SOCK environment variable. Perhaps I can do something creative with a remote command?
I welcome any ideas.
Do you really need a remote port? If you can ssh into the remote machine, why not run a command and send data back over the ssh command, like rsync, Mercurial, Git, and so on do. SSH can provide an 8-bit clean connection, so it's just like having a socket connection.
To be clear, what i am suggesting is:
SSH from origin to the destination
In the SSH session, run a command on the destination that writes data to its standard output
The standard output is sent over the SSH connection from destination to origin
Collect the data that emerges from the standard output of SSH on the origin machine
There is then no need to open a particular port on either the origin or the destination.
Indeed, if what you really want is "a protocol that will copy files from the remote system on demand", how about SCP, SFTP, or rsync over SSH?
I have this problem:
I have a server to which I ssh, and it has a special prompt request. The prompt is done by a ?prompt command.
It is fine with SSH, since the prompt I guess gets some input, but when I use SCP, the copy always fails.
So, I was wondering if there is maybe a flag for ssh and scp - so that interactive prompts are ignored.
(By the way, I need the prompt, so removing it isn't an option).
THANKS.
The prompt and response go into SSH stdio channels that are what scp uses to talk to the remote slave scp process, so it breaks the hand-shaking, and the transfer is aborted.
The right way to add additional prompts to SSH connections is through the keyboard-interactive authentication mechanism, probably with the help of some PAM module.
Your current approach just cripples SSH beyond simple usage patterns.