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

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33
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6answers
3k views

Linux equivalent to PowerShell's “one-to-many” remoting

Coming from Windows administration, I want to dig deeper in Linux (Debian). One of my burning questions I could not answer searching the web (didn't find it) is: how can I achieve the so called "one-...
33
votes
3answers
48k views

Restricting an SSH/SCP/SFTP user to a directory

Is there a simple way to restrict an SCP/SFTP user to a directory? All methods that I've come across require me to set a chroot jail up by copying binaries, but I don't think that should be necessary.
32
votes
7answers
9k views

My server is constantly being attacked [closed]

I am fairly new to the system administration world. I've been working on an application recently and when I check my application server logs, I constantly get various IP addresses trying to ssh into ...
32
votes
4answers
47k 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 ...
32
votes
2answers
13k views

Using an already established SSH channel

I have an already established ssh connection between two machines. Is there a way to send commands to the remote machine from a shell script that is run on the local machine, using the already open ...
31
votes
2answers
49k views

scp and compress at the same time, no intermediate save

What is the canonical way to: scp a file to a remote location compress the file in transit (tar or not, single file or whole folder, 7za or something else even more efficient) do the above without ...
29
votes
2answers
45k views

SSH and home directory permissions

It took me hours to solve this SSH problem with one of my class accounts on my school's servers. I couldn't ssh into one particular class account without entering my password, while passwordless ...
29
votes
3answers
8k views

How to close (kill) ssh ControlMaster connections manually

With the following .ssh/config configuration: ControlMaster auto ControlPath /tmp/ssh_mux_%h_%p_%r ControlPersist 4h How to close the persisting connection before the 4 hours? I know you can make ...
29
votes
4answers
11k views

Is there a way to communicate with someone at their desktop?

My wife is sitting at her home desktop, alpha, which is running a recent version of Ubuntu. I am on a bus, using ConnectBot on my G1 phone, and can SSH into alpha from wherever I am. For complicated ...
29
votes
4answers
25k views

Why SSH takes a long time to Connect

I have noticed that some Linux Servers in Network takes long time to connect using ssh. Situations: There are two situations I have faced: On some servers some times it takes a long time to ask ...
29
votes
2answers
5k views

What's the purpose of the randomart image for user (not host) SSH keys?

The ssh-keygen generates the following output: The key fingerprint is: dd:e7:25:b3:e2:5b:d9:f0:25:28:9d:50:a2:c9:44:97 user@machine The key's randomart image is: +--[ RSA 2048]----+ | .o o.. ...
28
votes
3answers
15k 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 ...
28
votes
2answers
80k views

Convert Amazon .pem key to Putty .ppk key Linux

I have generated and downloaded a private .pem key from AWS. However, to use Putty in order to connect to the virtual machine, I must have that key in .ppk format. The process of conversion is ...
28
votes
2answers
20k views

SSHFS specify key

I've got a question that I've not been able to find an answer for. I have two computers, both of which run Ubuntu Linux 12.04. I have set up my first computer ("home") to be able to SSH into my second ...
27
votes
6answers
40k views

How can I page up or down in tmux with Terminal.app?

When I am in tmux only a portion of the text shows up. If I try to scroll up or down the console scrolls up but not the actual text. If I do CTRL+b followed by [, I see in the status bar *tmux, and If ...
27
votes
4answers
4k views

How do I play an HTTP music stream over SSH?

I know I can just do mplayer <stream> to open and play a stream on the local machine. However, I'm behind a firewall. Instead, I'd like to open the stream on a remote machine, but still play it ...
27
votes
1answer
21k views

sshfs mount, sudo gets permission denied

I am using sshfs to mount a folder with some python projects over ssh to my ~/ directory. $ mkdir -p ~/mount/my-projects $ sshfs user@example.com:/home/user/my-projects ~/mount/my-projects I can ...
27
votes
5answers
7k 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?
27
votes
4answers
23k views

How to speed up X over SSH on a slow network connection?

Are there any specific recommendations on speeding up X applications over ssh on a slow network connection? In this specific case, I am accessing a server located in west coast from a laptop in east ...
27
votes
3answers
1k views

Do programs run from an ssh session depend on the connection?

Does a program that is run from an ssh session depend on the connection to the client? For example when the connection is really slow. So does it actively wait until things are printed on the screen? ...
26
votes
3answers
30k views

Permit root to login via ssh only with key-based authentication

I have some doubts about certain ssh server configurations on /etc/ssh/sshd_config. I want the next behavior: Public key authentication is the only way to authenticate as root (no password ...
26
votes
3answers
13k views

How to enable autocompletion for remote paths when using scp?

I remote copied a file to my laptop using: scp someFile USER@192.168.178.32:/home/USER/put/it/some/where/oh/damn/you/here I want to be able to autocomplete the remote path by hitting tab.
25
votes
5answers
32k views

how to avoid ssh asking permission?

We are attempting to speed up the installation of oracle nodes for RAC installation. this requires that we get ssh installed and configured so that it doesn't prompt for a password. The problem is: ...
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 ...
25
votes
2answers
89k views

how to connect ssh 'with' specified port?

I know how to connect 'to' a certain port when ssh'ing. ssh user@remotehostip -p XXX but is there a way to establish a ssh 'with' a certain port? I mean, is there a way to specify the port which ...
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 ...
24
votes
6answers
2k views

How can I propagate my SSH pub key to a list of servers without having to type my password in over and over?

I was recently given username/password access to a list of servers and want to propagate my SSH public key to these servers, so that I can login more easily. So that it's clear: There is not any ...
24
votes
5answers
27k views

Is there ever a reason to use scp instead of rsync?

Is there a reason to use scp instead of rsync? I can see no reason for using scp ever again, rsync does everything that scp does, with more safety (can preserve symlinks etc).
24
votes
4answers
10k views

Quoting in ssh $host $FOO and ssh $host “sudo su user -c $FOO” type constructs

I often end up issuing complex commands over ssh; these commands involve piping to awk or perl one-lines, and as a result contain single quotes and $'s. I have neither been able to figure out a hard ...
24
votes
2answers
23k views

SSH: tunnel without shell on ssh server

I have to set up a tunnel between two hosts. For this I use ssh in this way: ssh -L MY_LOCAL_PORT:FOREIGN_ADDRESS:FOREIGN_PORT MYUSER@SSH_SERVER after that, I log in to my SSH_SERVER. How can I ...
23
votes
7answers
78k views

Execute remote commands, completely detaching from the ssh connection

I have 2 computers, localpc and remoteserver. I need localpc to execute some commands on remoteserver. One of the things it needs to do is start a backup script that runs for a number of hours. I ...
23
votes
4answers
14k views

Why does `cd` command not work via SSH?

I was trying to backup some files via SSH but instead of tar'ing the ones I wanted I got my home folder. I did some further testing and it boils down to this: ssh root@server /bin/sh -c "cd /boot &...
23
votes
3answers
35k views

How to dd a remote disk using SSH on local machine and save to a local disk

How can I create a backup of a remote disk using SSH on my local machine and save it to a local disk? I've tried the following: ssh hostname@my.ip.address "sudo dd if=/dev/sdX " | \ dd of=/home/...
23
votes
3answers
71k views

How to ensure SSH port is only open to a specific IP address?

This is my /etc/sysconfig/iptables: It has two ports open 80 apache and 22 for ssh. # Firewall configuration written by system-config-firewall # Manual customization of this file is not recommended. ...
23
votes
1answer
29k views

Use different username by default for a specific host

I have a different (assigned, non-changable) username on one of the servers I log to regularly, and I would like to avoid writing it down every time. Can I make these lines [tohecz@localhost ~]$ ssh ...
23
votes
3answers
27k 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 ...
22
votes
1answer
29k views

Single command to login to SSH and run program?

Is there a way to structure a single command to login via SSH to a remote server and run a program on the remote login shell? In the OpenSSH manual, it reads "If command is specified, it is executed ...
22
votes
2answers
24k views

Terminate dropped SSH sessions

My SSH sessions seem to be dropping though that is not my major problem - the major problem is my previous sessions are still alive, worse yet one of them is running visudo preventing me from ...
21
votes
4answers
92k views

Keeping a process running after putty or terminal has been closed [duplicate]

I'm running a node.js server off of a raspbian (Debian) machine, and I'd like to start and stop the server remotely. This for me means using putty to access the shell, except when I close out of the ...
21
votes
5answers
28k views

Automated ssh-keygen without passphrase, how?

I would like to make an automated script that calls ssh-keygen and creates some pub/private keypairs that I will use later on. In principle everything works fine with.... ssh-keygen -b 2048 -t rsa -f /...
21
votes
3answers
14k 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 ...
21
votes
4answers
52k views

History of IP addresses that accesed a server via ssh

It has come to my attention that a server of mine has been hacked and infected with a known chinese botnet. It was a prototype/testing virtual machine with its own static IP(US address) so no harm ...
20
votes
8answers
20k views

How to rsync over ssh when directory names have spaces

I am new to Linux and am trying to rsync from one server to another. The servers have the same directory structure but I am having trouble getting the remotes server to properly recognize the path ...
20
votes
3answers
5k views

What are the pros/cons of the various methods to block brute force SSH attacks?

There are a number of different packages out there to shut out IPs from which brute-force SSH attacks are launched on your system. For example: DenyHosts Sshguard fail2ban What are the pros/cons ...
20
votes
2answers
8k views

(SSH) Is it dangerous to close terminal without “exit”?

This happened many times. While the SSH active, I'm so tired and just close the terminal without exit Is it dangerous to doing like that?
20
votes
3answers
12k 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 $...
20
votes
2answers
30k views

Use ssh with a specific network interface

I'm using openconnect to connect to vpn. After entering my credentials, I get this: POST https://domain.name/... Got CONNECT response: HTTP/1.1 200 OK CSTP connected. DPD 30, Keepalive 30 Connected ...
20
votes
2answers
9k views

Is there an easy way to update information in known_hosts when you know that a hosts key has changed?

If a host's operating system has been re-installed and had its public key regenerated sshing to it will of course fail because the new key doesn't match the old one. Is there an easier way to tell ...
20
votes
4answers
21k views

Is it possible to set Gnome Terminal's title to “user@host” for whatever host I'm connected to?

I'd like to set the terminal title to user@host so I can easily tell which machine I'm connected to from the window title. Is there a way to do this from SSH or from GNOME Terminal?
20
votes
6answers
30k views

How can I run a script immediately after connecting via SSH?

I started to ask this question but answered it while I had it open. I'm going to post this question, follow it up with my solution and leave it open to other potential solutions. <backstory> I'...