Secure Shell (SSH) is a protocol primarily for encrypted shell connections. This tag is also used for questions about sshd and openssh, the two standard applications for using SSH.

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how to ssh to the machine behind the firewall? [duplicate]

Possible Duplicate: SSH to a computer that will then SSH to another computer I have 3 Linux machines A, B and C. I can ssh from A to B; B to C but not from A to C directly because C is ...
38
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4answers
57k views

How to change sshd port on Mac OS X?

I want to change which port sshd uses on a Mac server. For example, let's say from port 22 to port 32. Editing /etc/sshd_config does not seem to work. Does anyone know how to change it? I'd prefer ...
53
votes
12answers
30k views

How can I run arbitrarily complex command using sudo over ssh?

I have a system that I can only log in to under my username (myuser), but I need to run commands as other user (scriptuser). So far, I have come up with the following to run the commands I need: ssh ...
100
votes
3answers
51k views

ssh hostname returns “Bad owner or permissions on ~/.ssh/config”

When I try to ssh to another box, I get this strange error $ ssh hostname Bad owner or permissions on ~/.ssh/config But I made sure that I own and have rw permissions on the file: ls -la ~/.ssh/ ...
44
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10answers
14k views

Why is SSH password authentication a security risk?

Most guides for OpenSSH configuration advise to disable password authentication in favor of key-based authentication. But in my opinion password authentication has a significant advantage: an ability ...
72
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1answer
49k views

SSH use only my password, Ignore my ssh key, don't prompt me for a passphrase

This is a question regarding the OpenSSH client on Linux, MacOSX and FreeBSD. Normally, I log into systems using my SSH key. Occasionally, I want my SSH client to ignore my SSH key and use a ...
31
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7answers
96k views

How can I edit the welcome message when ssh start?

I have a vps for my website hosting. It is running a ubuntu server. Every time I logged in my server by ssh, it displays a lengthy welcome message in my terminal. Linux node61.buyvm.net ...
46
votes
4answers
37k views

How can I launch a screen session with a command over ssh on a remote server from my desktop?

I want to be able to launch screen sessions on remote servers from a single ssh command on my desktop. However, screen seems to need a terminal, which is not available when running a command through ...
28
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1answer
6k views

Why does my OpenSSH key fingerprint not match the AWS EC2 console keypair fingerprint?

When I import my OpenSSH public key into AWS EC2's keyring the fingerprint that AWS shows doesn't match what I see from: ssh-keygen -l -f my_key It is a different length and has different bytes. ...
53
votes
4answers
19k views

How do I make ssh fail rather than prompt for a password if the public-key authentication fails?

I've got a script that ssh'es several servers using public key authentication. One of the servers has stopped letting the script log in due to a configuration issue, which means that the script gets ...
26
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2answers
39k views

public key authentication fails ONLY when sshd is daemon

I have no clue on how this happens. The distro is Scientific Linux 6.1 and everything is set up to perform authentication via public key. Yet, when sshd is running as a daemon (service sshd start), it ...
37
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9answers
40k views

How can I automatically change directory on ssh login?

I'm trying to get ssh to automatically change to a particular directory when I log in. I tried to get that behaviour working using the following directives in ~/.ssh/config: Host example.net ...
20
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5answers
9k views

How to handle SSH port changes with Ansible?

I'm trying to use Ansible for automating the setup process of new server instances. One of the setup tasks changes the default SSH port, therefore requiring me to update the hosts list. Is it ...
20
votes
3answers
34k views

How to check if a RSA public / private key pair matched

I have two files, id_rsa and id_rsa.pub, what command can be used to validate if they are the valid pair.
10
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3answers
7k views

Trying to get SSH with public key (no password) + google authenticator working on Ubuntu 14.04.1

I'm using Ubuntu 14.04.1 (with OpenSSH 6.6 and libpam-google-authenticator 20130529-2). I'm trying to set up SSH logins where the public key authenticates (without a password) and a user is prompted ...
9
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3answers
13k views

How can I use the same key for SSH and SSL (https)

I'm trying to install the development tools for a small team, and I can't get the authentication right. Since we are a distributed team, the server is on the internet. And I'd like to have SSO+zero ...
30
votes
7answers
6k views

SSH: Two Factor Authentication

I currently have a Ubuntu Server 12.04 running OpenSSH along with Samba and a few other services. At the current time I have public key authentication set up, and I'm wondering if it's possible to set ...
23
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6answers
8k views

Can I use PLink and Pageant with Cygwin's ssh?

I'm now using msysgit because of the GUI tools, which use Putty's Pageant and PLink utilities, but I use Cygwin as a general SSH terminal. I had been using ssh-agent on Cygwin, but that means I have ...
11
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10answers
19k views

DNS Name lookup (was SSH) Not Working After Snow Leopard Upgrade

I think this started with the Snow Leopard update. Cleaned out the .ssh directory, still having the issue. ~: uname -a Darwin california-example-com.local 10.0.0 Darwin Kernel Version 10.0.0: Fri ...
21
votes
6answers
15k views

How can I set proxy for subversion with ssh tunnel?

I want to check out/update the code via proxy since my local connection is slow. I setup ssh tunnel : ssh -D 8090 user@ssh.proxy.net to forward all the packets to my localhost:8090. How can I set up ...
10
votes
4answers
3k views

SCP filename tab completion

I use SCP regularly to move files between servers and I've heard rumoured that you can use tab-completion on the remote server if you're using public keys, but so far I have had no luck. What I'm ...
9
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3answers
17k views

How to stop/prevent SSH bruteforce

I'm very new to network administration, so please regard that I'm not that experienced yet. I have a Ubuntu root server with plesk panel. Yesterday my friends and I noticed that the quality of ...
22
votes
4answers
14k views

What is the benefit of not allocating a terminal in ssh?

Every once in a while I will do something like ssh user@host sudo thing and I am reminded that ssh doesn't allocate a pseudo-tty by default. Why doesn't it? What benefits would I be losing if I ...
19
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5answers
11k views

SSH: Do you use one private/public key pair for each remote machine? Or a single pair for all?

When you want to have public key based ssh logins for multiple machines, do you use one private key, and put the same public key on all of the machines? Or do you have one private/public key pair for ...
11
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4answers
6k views

When would ssh -t not be appropriate instead of ssh?

Using ssh -t instead of ssh for connections to remote servers has several advantages. For example, I can directly edit a file with vim: ssh -t host vim foo.txt, which would fail otherwise. Are there ...
10
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5answers
13k views

Can I create SSH to tunnel HTTP through server like it was proxy?

Say I have a server and client. I need to create connection from client to a website through server like it was proxy. Is it possible to do this using a SSH tunel, or do I have to install some proxy ...
21
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7answers
5k views

I screwed up, exit in .bashrc

I put "exit" in my .bashrc file. I don't have physical access to the machine so to connect to it I use ssh. I don't have root privileges. Every time I connect to the server, the connection ...
20
votes
7answers
7k views

Restart SSH on a machine where SSH is the only mode of access

I've made some changes to sshd_config file and therefore need to restart. I'm looking tips on safely restarting ssh when getting physical access to the server would be a huga PITA.
19
votes
14answers
40k views

Stop ssh login from printing motd from the client?

I've got SSH passwordless set up, however it prints the MoTD when it logs in. Is there anyway to stop that happening from the client side? I've tried ssh -q but that doesn't work. I don't want to use ...
15
votes
4answers
78k views

Free public SSH server for testing purposes [closed]

I'm writing an application that makes connections to SSH servers. It doesn't need anything specific from the server (except running under GNU/Linux). I need SSH servers for running my application ...
15
votes
4answers
6k views

Using PGP keys for SSH

I use a 4096 byte RSA PGP key; since SSH also uses the RSA standard, is it at all possible to use the PGP key as an SSH key without installing additional software on the server (and as little as ...
14
votes
2answers
31k views

bad ownership or modes for chroot directory component

I created the user MY_USER. Set his home dir to /var/www/RESTRICTED_DIR, which is the path he should be restricted to. Then I edited sshd_config and set: Match user MY_USER ChrootDirectory ...
14
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3answers
9k views

Set up sftp to use password but ssh not to use password

Is it possible to set up a user on ubuntu with openssh so that ssh does not use password authentication but sftp does? I assume that if I change /etc/ssh/ssh_config to have PasswordAuthentication yes ...
12
votes
3answers
12k views

How to perform a secure rsync between servers across an unsecured network

Basically what I'm asking is, has anyone come across a means by which to wrap rsync inside ssh. With OpenSSH v4.9+ sftp has some nice options that allow you to chroot the incoming connection and such ...
11
votes
4answers
28k views

SSH X11 not working

I have a home and work computer, the home computer has a static IP address. If I ssh from my work computer to my home computer, the ssh connection works but X11 applications are not displayed. In my ...
10
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2answers
12k views

SSH Connections freezing with “Write failed: Broken pipe”

I am connecting to a CentOS 5.5 box via SSH from a Ubuntu 11.04 machine. The connection appears to work as expected when it is in active use (i.e. no lag or loss), but if it is left inactive for a ...
10
votes
2answers
6k views

How can I close SSH tunnel gracefully?

I have open tunnel with ssh -2 -N -L 5001:localhost:1019 eonil@test.local The tunnel is working good, but I have to Ctrl+C or Ctrl+D to force quit the tunnel. How can I close the tunnel gracefully? ...
5
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2answers
2k views

Easy multi-level authentication for sudo

I have a FreeBSD server with password-based SSH enabled. I would like to enable sudo, but I do not want a potential attacker to be one password away from root access. My current solution is logging ...
3
votes
11answers
862 views

Ubuntu Server SSH

I have a server with ubuntu. I do work on it over SSH. I had a problem with brute force attempts over port 22. I changed the port and I assumed it fixed the brute force problem. Am I right or are the ...
17
votes
3answers
18k views

What options can be put into a SSH authorized_keys file?

I found this article on options that can be put before a key in the authorized_keys file. I was wondering though, are there more? Options listed in the article are from="domain" ...
14
votes
3answers
2k views

Inline SSH command

Is it possible to do a simple inline style SSH command, for example: ssh foo@bar.com { cd foo/bar && rm *.foobar }
12
votes
11answers
13k views

Best way to go about changing a root password on 3000+ Solaris, AIX, and Linux servers?

Long story short: Big old corporation, lots of UNIX/Linux servers. I inherited responsibility for a bunch of scripts that that left a few years ago. One of them was a script that would be run every ...
10
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2answers
3k views

SSH MOTD per user

I want to display banner (welcome message) for SSH users with a specific welcome message for each user.
9
votes
3answers
23k views

Rsync command issues, owner and group permissions doesn´t change

I´m trying to set owner and group via rsync and it doesn't seem to be working. This is the command: sudo rsync -rlptDvz --owner=cmsseren --group=cmsseren /home/serena/public_html/ -e ssh ...
9
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3answers
3k views

OpenSSH with public keys from database

Is it possible to fetch the public keys from a database instead of the authorized_keys file? I would like to use such a setup to manage ssh access to things like git repositories for multiple users ...
9
votes
5answers
9k views

How can I automatically change terminal colors when I ssh a server?

I'm frequently logging into different servers from my os x terminal window. I'd like to assign a color scheme for different hosts so that my terminal windows are easier to tell apart. Can this be ...
9
votes
4answers
7k views

Transfer files via SSH

I want to use file transfer via SSH on some scripts. I've read it's possible to tar over ssh. Where should I start reading?
8
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5answers
4k views

Stop ssh client from offering all the public keys it can find?

Like most sysadmins I use openssh all the time. I have about a dozen ssh keys, I like to have a different ssh key for each host. However this causes a problem when I am connecting to a host for the ...
6
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1answer
1k views

Adding port forwardings programmatically on a ControlMaster SSH session

I just found out about the ControlMaster/ControlPath feature of OpenSSH, which allows you to use a single SSH connection to run multiple terminals. As I often use SSH to use port forwarding to get ...
6
votes
8answers
22k views

Is it possible to prevent SCP while still allowing SSH access?

Using Solaris and Linux servers and OpenSSH, is it possible to prevent users from copying files using "scp" while still allowing shell access with "ssh"? I realize that 'ssh $server "cat file" ' type ...