SSH (Secure SHell) is a protocol for running commands on a remote computer.

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3
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4answers
3k views

passing passwords to a script

I want to scp a file to a remote host, and from there, run a command on the file, and exit the remote session. If I write a usual script, call scp and then ssh, I am prompted to enter two passwords. ...
6
votes
2answers
2k views

Non-ASCII printable characters in sshd banner

It's possible to configure a banner for sshd that is to be displayed as a connection is opened, via Banner /etc/motd.ssh in sshd_config. Note that this is displayed before the authentication occurs, ...
4
votes
1answer
1k views

Tunnel traffic through another machine over ssh

I want to be able to route a portion of my traffic through another machine over SSH. For example, is it possible to browse the web through the ssh tunnel and also browse the web through your LAN ...
2
votes
2answers
575 views

How can I ssh to a remote server with an automated password and no key?

I have a remote server. I planned to use public keys to connect over ssh without typing the password but the remote system rejects public key authentication. So what is the best way to do it? What ...
0
votes
1answer
52 views

Why am I still being asked for an ssh password when I'm using private key authentication?

I have Linux mint on my pc. I have a public/private key pair to ssh into my router without having to type the password. It works on Windows using putty, but Mint isn't when I run it from terminal. ...
62
votes
6answers
63k views

scp without replacing existing files in the destination

How do I copy an entire directory into a directory of the same name without replacing the content in the destination directory? (instead, I would like to add to the contents of the destination folder) ...
43
votes
5answers
53k views

Using while loop to ssh to multiple servers

I have a file servers.txt, with list of servers: server1.mydomain.com server2.mydomain.com server3.mydomain.com when I read the file line by line with while and echo each line, all works as ...
44
votes
3answers
21k views

How can I break away from an SSH session that has crashed?

Many times I have an SSH session that doesn't respond anymore (for example, when I lose internet connection and then reconnect). Ctrl+C, Ctrl+D, Ctrl+Z and a zillion of key presses don't have any ...
42
votes
1answer
48k views

How does tcp-keepalive work in ssh?

I am trying to code a shell-script that uses a ssh-connection for doing "heartbeats". I want to terminate the client- and server-side of that connection after a certain timeout (after the connection ...
31
votes
3answers
43k views

SSH inside SSH fails with “stdin: is not a tty”

I'm trying to connect to machine one with ssh and then connect to another machine two with ssh, but I get this error. ssh user@computerone.com 'ssh otheruser@computertwo.com' stdin: is not a tty ...
33
votes
5answers
123k views

ssh_exchange_identification: Connection closed by remote host (not using hosts.deny)

I'm not using hosts.allow or hosts.deny, further more SSH works from my windows-machine (same laptop, different hard drive) but not my Linux machine. ssh -vvv root@host -p port gives: OpenSSH_6.6, ...
13
votes
3answers
9k views

How to execute a remote command and pass in local file as input?

Is it possible to do this: ssh user@socket command /path/to/file/on/local/machine That is to say, I want to execute a remote command using a local file in one step, without first using scp to copy ...
24
votes
5answers
5k views

Why is Firefox so slow over SSH?

I try to launch Firefox over SSH, using ssh -X user@hostname and then firefox -no-remote but it's very very slow. How can I fix this? Is it a connection problem?
12
votes
3answers
2k views

Adding a user who can only execute scripts remotely

I would like to create a user who can only do one thing: via ssh specify a script ( and commandline arguments to the script ) that resides in one particular folder ( for the purposes of this question ...
8
votes
1answer
4k views

SSH over Socks proxy without username or password

I have a list of SOCKS proxy servers from this site. I've read about creating a dynamic tunnels with ssh -D and to be honest i've tried that already. Unfortunately for some reason I cannot connect to ...
27
votes
3answers
13k views

How can I determine if someone's SSH key contains an empty passphrase?

Some of my Linux & FreeBSD systems have dozens of users. Staff will use these "ssh gateway" nodes to SSH into other internal servers. We're concerned that some of these people use an unencrypted ...
19
votes
4answers
13k views

What's the difference between SFTP, SCP and FISH protocols?

I used to think SCP is a tool to copy files over SSH, and copying files over SSH is called SFTP, which is itself a synonym to FISH. But now as I was looking for a Total Commander plugin to do this in ...
12
votes
1answer
5k views

How to use ssh-agent with multiple (valid) keys and yet choose which one to use?

Let's say there are two keys A and B, both of which are valid for user@host public key authentication. Since authorized_keys is configured for different behaviour depending on the key, ~/.ssh/config ...
12
votes
1answer
793 views

How to execute an arbitrary simple command over ssh without knowing the login shell of the remote user?

ssh has an annoying feature in that when you run: ssh user@host cmd and "here's" "one arg" Instead of running that cmd with its arguments on host, it concatenates that cmd and arguments with spaces ...
6
votes
3answers
2k views

Keep running a script via ssh

ssh can use to run remote commands. ssh me@server.com 'long-script.sh' I run a long script that will take a lot of time, but I want to close my computer and keep running the script in the remote ...
3
votes
1answer
1k views

initiate ssh connection from server to client

We can easily connect via ssh to the remote machine that has public IP. But now I have a remote machine without public IP, and I need to connect to it from my machine that does have public IP. So ...
10
votes
2answers
8k views

dot file not sourced when running a command via ssh

When I run my program interactively, it works fine: ssh somehost $ ~/some/path/somescript.py When I run my program over ssh directly, it doesn't work. The variable PYTHONPATH is not set, because ...
9
votes
3answers
27k views

ssh, start a specific shell, and run a command on the remote machine?

I am in a situation where several users are sharing the same user account on a remote machine. I have a "personal" directory where I wrote my own .zshrc file, and I would like to have a way to: ...
7
votes
1answer
13k views

X11 forwarding an OpenGL application from a machine running an NVIDIA card to a machine with an AMD card

I'm interested in forwarding an X11 session over SSH, in order to launch a remote process that utilizes OpenGL (specifically, gazebo for anyone familiar.) The problem that I seem to be running into ...
5
votes
3answers
437 views

Why are rules not combining in an ssh config file?

It seems like the following would work as expected, i.e., that the second rule, having a hostname that matches the first rule, would apply it. Host *.hostname.com User myuser IdentityFile ...
4
votes
2answers
2k views

Execute bash commands over SSH while staying in interactive mode afterwards

Probably it is a weird thing I would like to achieve but: I would like to SSH to a remote host and then execute some bash commands like "alias" automatically to use them afterwards in an interactive ...
9
votes
2answers
4k views

Ssh login hook?

Is there a way to run a script/command every time a user connects using ssh? Can it be configured globally (i.e run the script when any user login)? I came across this question on Identica, but there ...
7
votes
2answers
5k views

How can I set up SSH on Linux to log in password-less?

My Raspberry Pi is running the default Debian image and has SSH enabled. I log into my Pi as follows: ssh pi@<IP-address-of-my-Pi> I have to enter my password every time. Can I somehow make ...
7
votes
4answers
3k views

How to debug SSH port forwarding

This is an extension to ssh port forward to access my home machine from anywhere I tried things mentioned there but I am not able to ssh to my machine. Netgear router settings for port forwarding: ...
1
vote
1answer
1k views

SFTP over reverse SSH tunnel?

I want to SFTP to a remote computer that is behind NAT. I can't modify the NAT router, so I have set up a reverse SSH tunnel using a middleman server. Here's what my SSH tunnel looks like: ...
12
votes
3answers
20k views

Why does my X11 forwarding attempt fail with “connect /tmp/.X11-unix/X0: No such file or directory”?

On my local machine, I run: ssh -X me@remotemachine.com (For completeness, I have also tested all of the following using -Y with identical results). As expected, this accesses remotemachine.com ...
5
votes
1answer
426 views

Automated ssh login with passphrase?

Logging onto a machine over ssh typically requires a password to be entered before access is granted. Alternatively, a key/certificate (without a passphrase) can be installed onto the remote machine ...
4
votes
1answer
3k views

ssh into an account which has no home directory

As a follow up to my previous question, I have decided to create the local user accounts as below. adduser --system --no-create-home USERNAME Now, I would like the local users to be able to access ...
3
votes
1answer
956 views

Route SSH to host through interface

Is it possible to route all outgoing requests for SSH (port 22) to mydynamicdns.afraid.org via wlan0 instead of eth0 when both are connected? Since my IP is dynamic, I would like to use a name ...
2
votes
1answer
538 views

SSH Connection into LAN without port forwarding?

I'm living inside a study union for the next few month. the organisation has its own network and gateways where the students are connected to the internet. problem: I don't have access to the routers ...
115
votes
4answers
131k views

Why do I need a tty to run sudo if I can sudo without a password?

I have configured sudo to run without a password, but when I try to ssh 'sudo Foo", I still get sudo: sorry, you must have a tty to run sudo. Why does this happen and how can I work around it?
63
votes
3answers
47k views

how can shellshock be exploited over SSH?

Apparently, the shellshock Bash exploit CVE-2014-6271 can be exploited over the network via SSH. I can imagine how the exploit would work via Apache/CGI, but I cannot imagine how that would work over ...
57
votes
2answers
136k views

List all connected SSH sessions?

I just SSH'd into root, and then SSH'd again into root on the same machine. So I have two windows open both SSH'd into root on my remote machine. From the shell, how can I see a list of these two ...
52
votes
4answers
12k views

Why is root login via SSH so bad that everyone advises to disable it?

Everybody on the Internet advises to disable root login via SSH as it is a bad practice and a security hole in the system, but nobody explains why it is so. What is so dangerous in enabling root ...
50
votes
5answers
38k views

How can I tell what version of Linux I'm using?

Often times I will ssh into a new client's box to make changes to their website configuration without knowing much about the server configuration. I have seen a few ways to get information about the ...
14
votes
4answers
11k views

Autocomplete server names for SSH and SCP

I have a few servers configured in ~/.ssh/config, such as alpha and beta. How might I configure Bash such that the commands ssh al<tab> and scp file.tgz al<tab> autocomplete the names of ...
29
votes
9answers
145k views

ssh_exchange_identification: read: Connection reset by peer

I am on OS X trying to ssh into a ubuntu 12.04 server. I was able to SSH in -- until abruptly stuff stopped working. I've read online to use the -v to debug this. Output is shown below. If I ssh into ...
19
votes
3answers
29k views

What difference between openssh key and putty key?

I've found that ssh-keygen ("ssh" package) produces different keys from puttygen ("putty" package). If I create public and private keys with ssh-keygen some ssh-servers will not accept my keys. If I ...
22
votes
3answers
24k views

Tell SSH to use a graphical prompt for key passphrase

How can I force SSH to request passphrases using a graphical prompt (GTK, for example) instead of the standard one that uses the terminal? I tried setting SSH_ASKPASS=/usr/bin/ssh-askpass but it ...
20
votes
3answers
11k views

How do I know if my ssh tunnel is created successfully?

I rely on the following script tunnel.sh written by others to keep a ssh tunnel alive: #!/bin/bash export SSH_HOST=tim@server if [ ! -f /tmp/.tunnel ] then echo "Creat SSH tunnel" ssh -f -D 9999 ...
35
votes
7answers
18k views

Can I find out which ssh key was used to access an account?

Is it possible to find out which ssh key was used to access an account? I have an account on a server that I let several (trusted!) people have access to via ssh. I'd find it useful to be able to ...
16
votes
3answers
10k views

Get ssh server key fingerprint

Is there a way to programmatically obtain a SSH server key fingerprint without authenticating to it? I'm trying ssh -v user@host false 2>&1 | grep "Server host key", but this hangs waiting for ...
10
votes
2answers
6k views

How can I make ssh ignore .ssh/config?

I have the following in my ~/.ssh/config. HOST 10.2.192.* USER foo PreferredAuthentications publickey IdentityFile ~/.ssh/foo/id_rsa The above configuration lets me connect ...
24
votes
2answers
2k views

Why is this binary file transfered over “ssh -t” being changed?

I am trying to copy files over SSH, but cannot use scp due to not knowing the exact filename that I need. Although small binary files and text files transfer fine, large binary files get altered. Here ...
25
votes
2answers
5k views

SSH output isn't line buffered?

I'm running a script on a remote machine like this: ssh $host "pip install -r /path/to/requirements.txt" But the output isn't line buffered; instead of seeing one line returned at a time, all the ...