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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12
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11answers
9k 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
votes
2answers
15k 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
votes
6answers
32k views

Linux closing connection after successful login

I am working on a server with Debian 5.2.2. Barely having any administrative knowledge with Linux, I think I screwed something up. I used apt-get update and apt-get upgrade to get everything up to ...
9
votes
2answers
4k views

Authentication Order with SSH

i am still have troubles mastering sshd - when I login with -v I see that ssh is authenticating the following way debug1: Authentications that can continue: ...
8
votes
2answers
11k views

SFTP fatal bad ownership or modes for chroot directory ubuntu 12.04

I just set up my SFTP server and it works fine when I use it from my first user account. I wanted to add a user which we will call 'magnarp'. At first I did like this in sshd_config: Subsystem sftp ...
8
votes
5answers
7k 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 ...
8
votes
1answer
2k views

SSH passphrase remembered in MacOSX Snow Leopard

I am facing a very strange situation with Snow Leopard. I have a Linux server, configured to accept an ssh connection authenticated only through RSA key. No password. On my laptop I correctly deployed ...
7
votes
3answers
2k 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 ...
7
votes
6answers
10k views

Can't get detached screen to resume

I use putty and have an unreliable wireless connection, so I use screen to keep my work going. Often I'll get disconnected, and then I can't reattach my screen. I'll run screen -D -RR and it will just ...
6
votes
3answers
1k views

Restricting the network access of Docker container

I'm in the process of creating an SFTP only Docker container, one that will be used by multiple people for the sole purpose of uploading and managing files in their own chrooted Environment. On ...
5
votes
8answers
17k 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 ...
4
votes
3answers
4k views

Is it possible to connect a EC2 Linux instance via ssh without the key pair?

I can connect to my EC2 Linux instance via ssh using the key pair (*.pem). Is it somehow possible to connect it with ssh with out the pem file?
3
votes
2answers
4k views

How to display SSH banner at login, but only for password authentication

I have a warning message that is displayed to a user after they enter their username to log in to our Linux servers. I only want to display this message for password authentications, and not when ...
2
votes
3answers
2k views

Wordpress can't find ssh public and private key pair

My server configuration is as follows: CentOS 5.8 (final) running Nginx. I am using the SSH2 feature of Wordpress's plugin installer. I have installed lib2ssh and it is working (Wordpress is ...
19
votes
4answers
19k views

Ssh, run a command on login, and then Stay Logged In?

I tried this with expect, but it didn't work: it closed the connection at the end. Can we run a script via ssh which will log into remote machines, run a command, and not disconnect? So ssh in a ...
13
votes
3answers
12k 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" ...
12
votes
1answer
3k views

Is it possible to run sshd as a normal user?

I'm aiming to start up a second sshd instance on a non-privileged port (e.g. 2222) with my own configuration file. Obviously, the sshd process can't setuid so logging in as users other than the one ...
10
votes
2answers
10k views

Why is ssh agent forwarding not working?

In my own computer, running MacOSX, I have this in ~/.ssh/config Host * ForwardAgent yes Host b1 ForwardAgent yes b1 is a virtual machine running Ubuntu 12.04. I ssh to it like this: ssh pupeno@b1 ...
8
votes
9answers
50k views

How can I map a SFTP to a Drive, natively in Windows

Today I saw that Vista and Win7 (which I am using) have the option to map ftp natively, according to this article: http://cybernetnews.com/cybernotes-map-a-ftp-to-a-drive-in-windows/ But I need to ...
7
votes
1answer
617 views

Conditional ProxyCommand in ~/.ssh/config?

I have my ~/.ssh/config configured with various hosts that are accessible either while on our company VPN, or via a SSH proxy server. At the moment I just have Host internal-server ProxyCommand ...
7
votes
1answer
1k views

Only allow password authentication to SSH server from internal network

I have an OpenSSH 5.9p1 server running on Ubuntu Precise 12.04 which accepts connections from both the internal network and the Internet. I'd like to require public key authentication for connections ...
7
votes
3answers
12k views

Allow scp/ssh for www-data user

I am on Amazon EC2 using Ubuntu 10.04.2 My web folder is owned by www-data so I want to be able to log into my server as www-data for ssh and scp. Thanks! Adding the line to my /etc/ssh/sshd_config ...
6
votes
2answers
9k views

SSH tunnel over multi hops using putty

I have a situation where I want to connect to a Linux machine running VNC (lets call it VNCServer) which is behind two consecutive Linux machines i.e., to ssh into the VNCServer, I have to ssh into ...
6
votes
4answers
2k views

Automatically-reconnecting TCP tunnel

I have an unreliable network connection between two machines: sometimes active TCP connections get dropped for reasons beyond my control. I want to establish a reliable TCP connection between the two ...
5
votes
2answers
12k views

execute su -c over ssh

I am trying to check the BIOS version of a server over SSH, a command that requires root privileges: ssh remote-server su -c dmidecode but this of course fails with the error: standard in must ...
4
votes
2answers
2k views

Remote server hangs, gets stuck. How to debug?

I have an vps running on VmWare ESX with Ubuntu 8.04 LTS. It has been running smoothly for the past 3 months, however recently we've notices two strange bugs. a. The server hangs, today was second ...
3
votes
1answer
1k views

SSH from Windows to Linux with AD certificates

I have a Windows client machine connected to Active Directory and a Linux server also connected to Active Directory (through PAM w/ LDAP), and I want to be able to do password-less SSH from Windows to ...
3
votes
3answers
5k views

Ubuntu-server: gitosis user naming convention

If you install gitosis on ubuntu-server 10.10 via apt-get: sudo apt-get install gitosis The post-install script will create a new gitosisuser. This user will be used to allow people to connect with ...
3
votes
6answers
2k views

Same command on multiple servers

I'm just wondering if there is any fellow sysadmin with the need to execute one command on multiple servers. If so, what technique are you using? I have grown tired to ssh-ing to 3-5 servers and ...
2
votes
1answer
2k 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 ...
1
vote
2answers
3k views

How does one determine active SSH and SAMBA connection counts?

I have a server that I use infrequently, so I'd like to cron a job to shutdown daily if no users are logged in via SSH and SAMBA shares. How can I determine how many active SSH connections there are, ...
14
votes
7answers
3k 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 ...
10
votes
5answers
22k views

Out of nowhere, ssh_exchange_identification: Connection closed by remote host

I am running Ubuntu 10.10 on a remote box. I ssh to it everyday without issues but today out of the blue, I get the following error: ssh_exchange_identification: Connection closed by remote host If ...
10
votes
8answers
18k views

Why can't I ssh into my new EC2 Instance?

I created a new instance (tiny, 64 bit AMI linux from Amazon) Created a new key pair called "mir". I downloaded mir.pem and put it in my ~/.ssh folder. I even did ssh-add mir.pem. Then I tried to ...
8
votes
4answers
20k 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 ...
8
votes
6answers
7k views

Find out how many DNS Queries/month via WHM or SSH?

Is it possible? We have complete control over our DNS server and the server actually being pointed to. We are interested in how many DNS Queries we are currently getting, as we want to move to Ultra ...
8
votes
6answers
8k views

Routing all traffic thru socks proxy using ssh -D

is it any easy way to route all traffic through a ssh proxy with -D? I can configure individual specific applications to do this, but I would like a configuration that routes all the traffic on the ...
7
votes
1answer
135 views

How to detect or log interrupted uploads with OpenSSH SFTP server?

I have this problem where a customer of ours has been SFTP-ing truncated data. I'm not sure if the problem is on our end or his. I've enabled SFTP logging but it does not allow me to detect if an ...
7
votes
4answers
12k views

In Fail2Ban, How to Change the SSH port number?

In my server, the ssh port is not the standard 22. I have set a different one. If I setup fail2ban, will it be able to detect that port? How can I tell it to check that port rather than port 22? The ...
7
votes
2answers
4k views

How to revoke an ssh certificate (not ssh identity file!)

I've generated an ssh certificate like this: ssh-keygen -f ca_key # generate a ssh keypair for use as a certificate generate a host key ssh-keygen -s ca_key -I cert_identifier -h host_key.pub ...
7
votes
5answers
2k 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
votes
4answers
6k views

Create SSH user with limited privileges to only use Git repository

I have a git repository hosted on my SunOS server, that I remotely use through ssh git clone ssh://myUser@mydomain.com/path/to/git Now I need to add more users to be able to access that repository, ...
6
votes
3answers
2k views

What exactly does ssh send when performing key negotiation?

When explicitly specifying identity file to ssh: ssh -i ./id_rsa ... I have these lines in ssh debug trace: debug1: Offering public key: ./id_rsa debug3: send_pubkey_test debug2: we sent a ...
6
votes
4answers
7k views

Problem using a public key when connecting to a SSH server running on Cygwin

We have installed Cygwin on a Windows Server 2008 Standard server and it working pretty well. Unfortunately we still have a big problem. We want to connect using a public key through SSH which doesn't ...
5
votes
5answers
2k views

Email notification about each SSH connection to Linux server

I would like to be notified about each SSH connection to the Linux (Debian) server. Already saw some methods, which proposed to add mail command into own .bashrc, but this approach seems not to cover ...
5
votes
3answers
5k views

Trying to setup chroot'd rsync

I'm trying to set up a backup server. I want to chroot each user (client) to its home directory, and only allow it to use sftp and rsync. I quickly discovered that I was not the only one trying to do ...
5
votes
4answers
8k views

ubuntu server, ssh, write failed: broken pipe

I'm getting some bizarre behavior with Ubuntu Server 10.04 64bit on two of our new servers (both fresh installs). I have ubuntu server (same version) deployed on 4-5 other servers without this issue. ...
5
votes
2answers
1k views

How can I setup OpenSSH per-user authentication methods?

I'd like to be able to have one set of users authenticating using public key auth and other users to use password authentication. Is this possible in OpenSSH on Linux? If so how do I go about it? ...
5
votes
5answers
2k views

SSH session drops - Does the command continue executing?

If I was running a command before the SSH connection was dropped, will the command continue executing?
5
votes
2answers
2k views

Differences between SSH's tunnels and OpenVPN

I discovered that recent OpenSSH has support for tun devices. When it comes to tunnels and VPNs, I always thought the main programme was OpenVPN. Are there any advantages to using SSH tunnels? What ...