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

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6
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2answers
6k views

How to use SSH to make a dd copy of disk A from host B and save on disk B?

I want to make remote backups from disk A at will using SSH from computer B. I want to save the backups to disk B. How can I do this? I've tried using $ ssh hostname@my.ip.add.ress "sudo dd ...
2
votes
4answers
2k views

Wrong root shell in /etc/passwd

I wanted to change the standard shell for my root user to bash but I got the path wrong. i typed /bin/bash instead of /opt/bin/bash. Now my /etc/passwd looks like this: ...
6
votes
2answers
465 views

Public key f3:6e:87:04:ea:2d:b3:60:ff:42:ad:26:67:17:94:d5 blacklisted (see ssh-vulnkey(1)); refusing to send it

I'm reproducing the Debian PRNG vulnerability from 2008 in a lab environment. Now I'm trying to SSH into the machine, but every time I try to send the private key I get: Public key ...
3
votes
1answer
265 views

Changed SSH port without allowing it through firewall, locked out now - what to do?

I have a VPS where I changed the SSH port from the default 22. Unfortunately I forgot to allow the new port through the firewall. I don't have physical access to the server, and my host does not seem ...
15
votes
3answers
1k views

Why change default ssh port?

I've noticed lot of admins change default ssh port. Is there any rational reason to do so?
0
votes
1answer
54 views

block from SSH and FTP

yesterday i was upload some images using filezilla to my VPS , and today when i tried to login into my VPS i got connection time out , same thing when i tried to access using FTP. but i can acces ...
1
vote
0answers
85 views

Why does having cron run a remote command over ssh on a Cisco router get interrupted?

I have been tasked with making sure that if a particular server at work dies, we know about it right away. Because I'm not there (no one is really), I have written a script to run on my home router ...
5
votes
0answers
60 views

HURD: Why is remote process not killed?

On most UNIX systems this will not leave a process running: ssh example.net sleep 1000 <<CTRL-C>> I have tested this behaviour on aix centos debian dragonfly freebsd hpux irix mandriva ...
8
votes
2answers
2k views

How to restrict an SSH user to only allow SSH-tunneling?

How can I restrict a user on the ssh server to allow them only the priviledges for SSH TUNNELING? i.e. So they cannot run commands even if they log in via ssh. My Linux servers are Ubuntu 11.04 and ...
3
votes
1answer
57 views

What is the difference between letting nohup append to 'nohup.out' and explicitly redirecting it to a file?

Consider the following scenario: tail.sh: #!/bin/bash tail -f test.txt invoke.sh: #!/bin/bash nohup ./tail.sh & invoke_explicitredirect.sh: #!/bin/bash nohup ./tail.sh > out.log & ...
10
votes
7answers
413 views

Why does my Python background process end when SSH session is terminated?

I have a bash script that starts up a python3 script (let's call it startup.sh), with the key line: nohup python3 -u <script> & When I ssh in directly and call this script, the python ...
2
votes
2answers
883 views

I want to suppress “no access to tty” error message?

I have a bash script where I use ssh to connect to another server and run some commands there. I found some sites that the error (Warning: no access to tty (Bad file descriptor). Thus no job control ...
2
votes
1answer
56 views

Concatenate and pass as parameter, bash

Need some help with removing default gateway. For example, there is an IP 192.168.4.15 with default gateway 192.168.4.14. I connect to WLAN with gw 10.0.0.1 and after that I would like do remove ...
3
votes
1answer
103 views

Connecting SSH and Git to gpg-agent

I'm running a YubiKey NEO with the OpenPGP applet to store my GPG keys on the smart card. I've stopped all other SSH and GPG agents manually by removing their startup entries (On elementary OS Luna, ...
3
votes
0answers
44 views

Why is my SSH authentication socket different from the man pages?

These two entries of man ssh-agent describe the SSH authentication socket: $TMPDIR/ssh-XXXXXXXXXX/agent.<ppid> UNIX-domain sockets used to contain the connection to the authentication ...
1
vote
0answers
20 views

Mosh and terminal multiplexing

Reading this Q&A on the site: Can I re-attach to a mosh session? made me wonder about the use cases for mosh. Say I start tmux on my local client, and then mosh to a remote host from within ...
1
vote
1answer
85 views

Can't change gnome-terminal tab's title from within ssh session on remote debian 8 machine

When I connect to a debian 8 server I can't change gnome-terminal tab's title, see for yourself: $ ssh deb6-server $ echo -en '\e]0;test\a' # title changes $ echo $TERM xterm-256color $ cat ...
0
votes
1answer
58 views

Sudo command not working on Intel Galileo Gen 1

I have an Intel Galileo Gen 1 Arduino board and I am using it over SSH with Ethernet. When I try to use the sudo commands the bash terminal reports this, a missing command! I am using the bigger Linux ...
-1
votes
1answer
45 views

Does a Linux server use swap space of an SSH client? [closed]

I currently am SSHing into a Linux server via my mac's terminal program. Afterwards, I run whatever simulations and calculations I need to do. However, I noticed that after I log in, it says on the ...
1
vote
1answer
46 views

How to disable GUI for password promt in Gnome

I moved from Xubuntu to Debian and copied id_rsa and id_rsa.pub to ./ssh/ I use a passphrase protected certificate to log in to a remote server. My passphrase contains arrows. Somethin like "Mike" ...
1
vote
3answers
1k views

Port 22 connection refused

I’m trying to copy a disk image over ssh to my local machine using this tutorial on linodes website. I know this could be posted on their support forum, but im convinced its in the general realm of ...
0
votes
1answer
35 views

Ugly bash function to send commands and “say” anything in screen over ssh. Is there a better way?

I’m working on a function this works but it is ugly. One thing that could be changed is being able to know the name of the screen. Using screen -dms minecraft java ….jar now starts a screen session ...
0
votes
1answer
236 views

“Shell connection” item disappeared from Midnight Commander menu

I have performed an upgrade of my distro (openSUSE 13.1 -> 13.2) and now no long see menu item in Midnight Commander that allows me to perform operations with remote files via SSH. Coressponding menu ...
6
votes
1answer
132 views

Cannot run cryptsetup throught SSH?

I'm trying to open a LUKS drive through SSH directly. ssh root@XX "cryptsetup luksOpen /dev/sdb3 secure But, no password prompt and it stuck. debug1: Sending command: cryptsetup luksOpen /dev/sdb3 ...
0
votes
0answers
56 views

Establish reverse ssh tunnel at OS startup / network connection up

I'm trying to setup a reverse SSH tunnel using a middle-man, due to firewall restrictions. I took the following steps: from ssh server do reverse tunnel: ssh -R 8080:localhost:22 ...
13
votes
1answer
15k 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 ...
6
votes
5answers
572 views

Use two different ip addresses per host in SSH

I have a server, named gamma, constantly up and running at work. Sometimes I connect to it from at home, in which case I use the public IP address 55.22.33.99. Sometimes, I connect to it when I'm at ...
1
vote
1answer
142 views

Remote ssh command not sending echo variable from a ksh script on AIX

I'm need to get the value of a variable from a remote host in a script using SSH and have to source an environment file first that does a shift at the end of its run. The command works locally and I ...
0
votes
0answers
29 views

Is there a large performance difference between find and find2perl

Is there a performance difference between find and find2perl? I work for a hosting company and I was told that our admins prefer us to use find2perl over find. Supposedly this is because find is ...
1
vote
1answer
35 views

How does 'ssh-copy-id' work under the hood?

What does the program ssh-copy-id actually do under the hood? Can the steps be explained as if to a child with a good understanding of computer science? Does it use protocols already existing in the ...
2
votes
0answers
33 views

X forwarding from a mac to Linux fails

I have been having problems recently while trying to ssh into linux servers (Ubuntu 14.04) from my mac (OSX Yosemite 10.10). This used to work fine until my latest update, where I systematically get a ...
2
votes
1answer
59 views

What will happen if I export my $HOME variable upon login?

This is a follow up from this question: http://askubuntu.com/questions/563828/how-to-change-my-home-directory?noredirect=1#comment775654_563828 The summary is: running ubuntu 14.04 ssh'ing into it ...
4
votes
2answers
231 views

How to decrypt hostnames of a crypted .ssh/known_hosts with a list of the hostnames?

I try to find a script to decrypt (unhash) the ssh hostnames in the known_hosts file by passing a list of the hostnamses. So, to do exactly the reverse of: ssh-keygen -H -f known_hosts Or also, to ...
0
votes
1answer
81 views

How can I use SSH to tunnel Minecraft clients to my MineOS server?

I have a MineOS Turnkey server running on my university's network and its locked behind their firewall. I have been able to connect to their Linux servers using SSH and then SSH to my server from ...
5
votes
4answers
2k views

SSH tunnel hanging

I'm trying to use an SSH tunnel from home to a computer in the university so I can access some articles. Both machines are running Ubuntu 11.04, the university machine runs openssh-server. I my ...
2
votes
4answers
2k views

Run if statement on remote machine

I'm trying to run a set of commands on a remote machine, that includes an if statement. I'm using this to shutdown a list of kvm instances. The first line should be fine, but could be prettier, rest ...
1
vote
2answers
45 views

Safe way of letting users upload their public keys

I need to let untrusted users, strangers, upload their id_rsa.pub to my server and onto a given user's authorized_keys (user git in my case). What is the safest way of achieving that, without having ...
1
vote
1answer
48 views

Preventing user from accessing parent folders [duplicate]

I have a user who I only want to be able to access /var/www/ucp/ (his home directory). I have executed the following command on the / directory, the /var/ directory and the /var/www/ directory: chmod ...
1
vote
1answer
93 views

Run a GUI application in background and reconnect later [duplicate]

Is there a way to run a Gui application (X11) in background so that if I disconnect, I can resume the running app again? I am using SmarTTY on windows to connect to remote CentOS. When I run a Gui ...
0
votes
1answer
21 views

SASL authentication fails when called from crontab

When I run mbsync from the command line it works fine. But if mbsync is run from the crontab, mbsync fails with this error "Error: SASL(-1): generic failure:". My guess is that mbsync's SASL ...
9
votes
2answers
742 views

How do I force a user to change a password at the first time login using ssh?

I'm trying to force a newly created user to change a password at the first time login using ssh. For security reasons I want to give him a secure password until he logs in for the first time. I did ...
6
votes
5answers
12k views

Disable user shell for security reasons

We have several user accounts that we create for automated tasks that require fine-grained permissions, such as file transfer across systems, monitoring, etc. How do we lock down these user accounts ...
0
votes
1answer
283 views

CentOS 7 add new user with root privileges

I am reading this tutorial, and trying to create a new user with root privileges and then block root access via ssh in a CentOS 7 server. The problem is that the new user is blocked from doing root ...
0
votes
1answer
894 views

ssh connection to server closed after authentication immediately

I'd like to connect ssh://challengeuser@web1.ncc.ninja:2222, but after the authentication and the example output below are displayed, the connection is closed immediately. I can use ssh to connect ...
0
votes
1answer
93 views

Create A Script That Responds To A Password Prompt

I'm writing a shell script that will respond to a prompt. For example, when I execute a file, the executed file will then prompt the user with this: Please enter the password: Then I want the script ...
2
votes
1answer
66 views

upload and dowload the files from server without giving password

I want to download the file from sever by using cron job, so I need to use scp command without giving password by keyword. How do I do so?
1
vote
2answers
193 views

Have SSH on port 80 or 443 while webserver (nginx) is running on these ports

I have a remote Linux (Debian) machine which I'd like to access from a very restricted network. In fact the only two open ports are port 80 (for HTTP) and 443 (HTTPS). On this machine I have nginx ...
1
vote
0answers
55 views

SSHD_CONFIG keeps corrupting on reverse SSH setup

I have a reverse SSH setup to traverse an impenetrable CGN NAT. It works well, but the SSHD daemon on the client behind the NAT keeps dieing for unknown reasons (fails to start-up). The client ...
2
votes
1answer
49 views

encfs automount and authorized_keys

Here's my problem: I have encfs configured in such a way that on login the subfolder ./private is mounted. However, when I use the workstation remotely via ssh, I don't give my password on login, ...
0
votes
2answers
37 views

How to instablock IP based on root SSH login

I have had this setup before by a friend of mine but it got lost in a reinstall. Basically what happened was, whenever someone would directly SSH to my server as root their IP would get blocked, you ...