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

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33
votes
1answer
38k 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 ...
23
votes
4answers
18k 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 ...
18
votes
4answers
17k 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?
12
votes
3answers
7k 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 ...
19
votes
5answers
2k 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?
7
votes
1answer
3k 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 ...
26
votes
3answers
90k 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, ...
17
votes
4answers
9k 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 ...
11
votes
1answer
3k 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 ...
20
votes
4answers
9k 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 ...
11
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
2answers
30k views

How to add a ssh user who only has permissions to access specific folder?

How to add an ssh user who only has permissions to access specific folder? useradd -d /var/www/xyz.com.tr/musteri -s /bin/bash -g sshd musteri I created a user called musteri. I set its home ...
9
votes
7answers
19k views

How do I work with GUI tools over a remote server?

I have an Ubuntu server running on EC2 (which I didn't install myself, just picked up an AMI). So far I'm using putty to work with it, but I am wondering how to work on it with GUI tools (I'm not ...
6
votes
3answers
1k 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 ...
6
votes
1answer
9k 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 ...
6
votes
2answers
5k 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 ...
5
votes
2answers
270 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 ...
7
votes
2answers
4k 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
2k 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: ...
10
votes
3answers
14k 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
340 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 ...
3
votes
1answer
849 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
369 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 ...
73
votes
4answers
75k 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?
60
votes
3answers
42k 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 ...
20
votes
3answers
9k 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 ...
17
votes
3answers
16k 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 ...
14
votes
3answers
15k 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 ...
29
votes
7answers
13k 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 ...
32
votes
5answers
27k 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 ...
21
votes
2answers
4k 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 ...
19
votes
2answers
1k 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 ...
13
votes
3answers
11k views

Differences between VNC and ssh -X

Why would you use VNC (or for that matter NX) instead of just using ssh -X (-Y). I read that VNC uses less bandwidth, but is there any other differences/advantages with respective tool?
11
votes
2answers
3k views

Detach/reattach an application run on X over SSH?

I have a development server that I leave running all the time, and a development laptop that I turn off/on everyday. I have a GUI application on the server that I'd like to run over SSH -X, and I'd ...
8
votes
4answers
5k 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 ...
6
votes
4answers
23k views

Pseudo-terminal will not be allocated because stdin is not a terminal

I'm trying to set up automatic SSH hopping through a server which doesn't have nc. This works from the command line: ssh -A gateway ssh steve@target (I have added my public key to the SSH agent). ...
6
votes
4answers
19k views

Set some firewall ports to only accept local network connections?

Basic firewall question: How do I set up the firewall on a system in a LAN so that some ports are only open to connections from the local area network, and not from the outside world? For instance, ...
4
votes
4answers
2k views

Copy text from one terminal into another

I am logged into ssh to a university account from my home computer. Then I find a file that I want to copy onto my local system. So I open a new shell terminal and am about to use scp to copy that ...
11
votes
3answers
18k views

ssh remote server on some port other than 22 without password

I am usually connecting to the remote server with ssh user@server.com -p 11000 and then giving the password each time for user. How should I avoid entering the password each time I connect ...
10
votes
5answers
19k views

Can a linux user change their password without knowing the current password?

I'm setting up a few ubuntu boxes, and using opscode's chef as a configuration tool. It would be fairly easy to install public keys for each user on each of these servers, and disable password ...
10
votes
3answers
19k views

Can I connect to or view abandoned ssh sessions?

I have a virtual instance of redhat running that I can ssh to from any host on the corporate network. My ssh session was dropped while running some scripts that may or not have caused me to ...
8
votes
2answers
2k views

How to efficiently use 3D via a remote connection?

I have one weak PC (client) but with acceptable 3D performance, and one strong PC (server) which should be capable of running an application using OpenGL twice, i.e. once locally and once remotely for ...
5
votes
3answers
1k views

Kill backgrounded SSH when shell exits

I'm trying to spawn an SSH from my bash profile script that runs in the background for connection sharing (via its control socket). The problem I'm running into is a reliable way to ensure the SSH ...
3
votes
1answer
4k views

Compress a directory using tar/gz over SSH to local computer?

I'd like to essentially tar/gz a directory on a remote machine and save the file to my local computer without having to connect back into my local machine from the remote one. Is there a way to do ...
10
votes
3answers
28k views

How to pull a file from a server using scp?

I am on machine A and want to pull a file from machine B. A$ scp <myuserid>@hostB:<path of file in B> . it says that: scp: <path of file in B>: No such file or directory But on ...
8
votes
3answers
21k 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: ...
8
votes
4answers
32k views

How to make putty to not break my session after some time?

Each time putty is breaking session after some time if I am doing nothing. There is no any time parameter on putty so how can I stay my putty ssh session always Alive ?
6
votes
3answers
5k views

A Web ssh/telnet client

I'm in kind of a tight spot right now. I wanted to know if someone has seen a HTML, or PHP web ssh client as both my company and school block everything besides port 80. I'm a control freak when it ...
4
votes
1answer
13k views

Installing fail2ban on CentOS 7

I am using @GarethTheRed 's answer to this question to install fail2ban on a remote CentOS 7 server. I am able to complete all the steps up until tail -f /var/log/fail2ban.log, at which point I get ...