Questions tagged [ssh]

Secure Shell; a network protocol that allows data transfer over a secure channel between two networked devices.

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647
votes
18answers
684k views

How to tell git which private key to use?

ssh has the -i option to tell which private key file to use when authenticating: -i identity_fileSelects a file from which the identity (private key) for RSA or DSA authentication is read.  The ...
588
votes
12answers
188k views

macOS keeps asking my ssh passphrase since I updated to Sierra

It used to remember the passphrase, but now it's asking it to me each time. I've read that I need to regenerate the public key with this command, which I did: ssh-keygen -y -f id_rsa > id_rsa.pub ...
352
votes
5answers
89k views

What is randomart produced by ssh-keygen?

When you generate a key, you get "randomart" from newer versions of OpenSSH. I am unable to find an explanation of why, and what I'm supposed to use it for. Generating public/private rsa key pair. ...
332
votes
14answers
291k views

An SSH tunnel via multiple hops

Tunneling data over SSH is pretty straight-forward: ssh -D9999 username@example.com sets up port 9999 on your localhost as a tunnel to example.com, but I have a more specific need: I am working ...
289
votes
12answers
326k views

How to fix warning about ECDSA host key

I'm trying to setup password-less SSH on an Ubuntu server with ssh-copy-id myuser@myserver, but I'm getting the error: Warning: the ECDSA host key for 'myserver' differs from the key for the IP ...
257
votes
13answers
300k views

Too many authentication failures for *username*

I have a hostgator account with ssh access enabled. When trying to upload the generated .pub key file with this command: rsync -av -e "ssh -p2222" /home/user/.ssh/key.pub username@111.222.33.44:.ssh/...
245
votes
7answers
643k views

How do I exit an SSH connection?

I’m connecting to a server via SSH to send a message to a socket server using a command like: ssh 181.169.1.2 -p 5566 After the connection is established and I write the message and send it I can’...
235
votes
6answers
163k views

Way to avoid ssh connection timeout & freezing of GNOME Terminal

When I connect via ssh to certain servers, it timeouts and "freezes" the terminal (doesn't accept input, doesn't disconnect, can't Ctrl-C to kill the ssh process or anything). This is in Ubuntu's ...
235
votes
15answers
180k views

How to reliably keep an SSH tunnel open?

I use an SSH tunnel from work to go around various idotic firewalls (it's ok with my boss :)). The problem is, after a while the ssh connection usually hangs, and the tunnel is broken. If I could at ...
188
votes
4answers
267k views

How to convert .ppk key to OpenSSH key under Linux?

I know that is possible to convert .ppk under puttygen in Windows, but how to do that on Linux? Is this possible ?
174
votes
7answers
133k views

How to make ssh tunnel open to public?

Well, referring back to this question, I am running the command ssh -R 8080:localhost:80 -N root@example.com on a Mac. Yet the port that is being tunneled is not working publicly. I am running such ...
169
votes
7answers
167k views

How can I avoid SSH's host verification for known hosts?

I get the following prompt everytime I try to connect a server using SSH. I type "yes", but is there a way to aovid this? The authenticity of host '111.222.333.444 (111.222.333.444)' can't be ...
162
votes
5answers
163k views

What's the difference between SCP and SFTP?

Usually, I use the scp command to transfer files on *nixes. What's the difference between SFTP and SCP? Don't they both work on SSH?
153
votes
10answers
126k views

How do I set up SSH so I don't have to type my password?

How do I set up SSH so I don't have to type my password when connecting to a host?
141
votes
9answers
143k views

How to use Mac OS X Keychain with SSH keys?

I understand that since Mac OS X Leopard the Keychain has supported storing SSH keys. Could someone please explain how this feature is supposed to work. I have some RSA keys that I've generated ...
138
votes
2answers
109k views

How do you run a SSH server on Mac OS X?

How do you run a ssh server on Mac OS X?
136
votes
4answers
104k views

scp between two remote hosts from my (third) pc

I have two remote hosts. host1-> 10.3.0.1 host2-> 10.3.0.2 Both run an ssh server. The ssh server listens on port 22 in host1 and on port 6969 in host2. Now, using my local machine, I need to copy ...
131
votes
12answers
57k views

Is there a way for one SSH config file to include another one?

In case it matters: OS: Ubuntu 10.04 SSH: OpenSSH_5.3p1 Debian-3ubuntu5 I'd like one SSH config file to include another one. The use case would be to define whatever I want in my default .ssh/...
129
votes
11answers
391k views

Remove key from known_hosts

I built several virtual machines during the last few weeks. The problem is, the .ssh/known_hosts gives me the Man in the middle warning. This happens because another fingerprint is associated with the ...
128
votes
5answers
178k views

What is a SSH key fingerprint and how is it generated?

I always find that I get this message when I ssh into a new machine: 12:f8:7e:78:61:b4:bf:e2:de:24:15:96:4e:d4:72:53 What does it stand for? Will every machine have the same fingerprint every time? ...
118
votes
5answers
78k views

SHA256 ssh fingerprint given by the client but only md5 fingerprint known for server

When connecting to a new/unknown server (with recent OpenSSH), for example: ssh example.com You get the fingerprint like below: The authenticity of host 'example.org (192.0.2.42)' can't be ...
117
votes
7answers
177k views

How can I tunnel all of my network traffic through SSH?

Whenever I'm using the internet from an insecure location (such as public wifi) I like to use an ssh tunnel (ssh -D port host) to ensure my traffic can't be sniffed. Unfortunately, there seem to be ...
110
votes
7answers
56k views

Don't add hostkey to known_hosts for SSH

I want to connect to a host via SSH but I don't want the hostname to be added to my ~/.ssh/known_hosts. How can I do that?
110
votes
15answers
889k views

How do I fix a “cannot open display” error when opening an X program after ssh'ing with X11 forwarding enabled?

After launching the X11 app (XQuartz 2.3.6, xorg-server 1.4.2-apple56) on my Mac (OS X 10.6.8), opening an terminal in X11 and running xhost +, I then ssh -Y to my Ubuntu 10.04 VM (running on VMware ...
110
votes
7answers
46k views

Forward SSH traffic through a middle machine

SSH tunneling is very confusing to me. I am wondering if I can do this in Linux. I have 3 machines.. A. My local machine at home. B. Machine at work that I can SSH into (middle man). C. My desktop ...
110
votes
5answers
57k views

Is it ok to share private key file between multiple computers/services?

So we all know how to use public key/private keys using SSH, etc. But what's the best way to use/reuse them? Should I keep them in a safe place forever? I mean, I needed a pair of keys for accessing ...
105
votes
1answer
109k views

Where does Putty store known_hosts information on Windows?

How do I tell if Putty already knows about and has cached credentials for specific ssh servers? Another way to ask this question is what is the Windows/Putty equivalent of a unix/ssh known_hosts file?...
101
votes
8answers
80k views

How do I configure SSH so it dosen't try all the identity files automatically?

I have been putting my ssh identity files inside my ~/.ssh/ folder. I have probably about 30 files in there. When I connect to servers, i will specify the identity file to use, with something like ...
101
votes
7answers
125k views

How do I make Bash my default shell on Ubuntu?

I have a .bash_profile in my home directory, but it isn't getting run on login. If I do the following, then things seem to be as I expect: ssh myhost bash source ~/.bash_profile But normally that ...
99
votes
5answers
164k views

How can I SSH into “Bash on Ubuntu on Windows 10”?

I have Windows 10 Anniversary Edition with "Bash on Ubuntu on Windows" installed and working. I'd like to be able to SSH into this Ubuntu instance, but although I have openssh-server installed and ...
98
votes
1answer
50k views

How can I tell how many bits my ssh key is?

I already created an ssh key for myself sometime in the past. I don't remember "how many bits" it is. How can I tell? I'm wondering because I'm using hosting at nearlyfreespeech.net and their faq ...
95
votes
22answers
146k views

Why is my SSH login slow?

I'm seeing delays in SSH Logins. Specifically, there are 2 spots where I see a range from instantaneous to multi-second delays. Between issuing the ssh command and getting a login prompt and between ...
92
votes
8answers
117k views

When ssh'ing, how can I set an environment variable on the server that changes from session to session?

When I ssh into a server, how can I pass an environment variable from the client to the server? This environment variable changes between different invocations of ssh so I don't want to overwrite $...
89
votes
6answers
571k views

How do I edit text files in the Windows command prompt?

On Unix I'd just use vi, but I don't know what the command is on Windows. I am actually trying to edit files over SSH with Windows Server 2008.
89
votes
10answers
96k views

Windows SSH: Permissions for 'private-key' are too open

I've OpenSSH 7.6 installed in Windows 7 for testing purposes. SSH client & server work just fine till I tried to access one of my AWS EC2 box from this windows. It seems like I need to change the ...
83
votes
7answers
210k views

SSH: The authenticity of host <host> can't be established

What does this message mean? Is this a potential problem? Is the channel not secure? Or is this simply a default message that is always displayed when connecting to a new server? I am used to ...
82
votes
9answers
22k views

How to disable scary terminal commands?

How do you disable scary terminal commands? I was using SSH to access a remote Ubuntu server without access to the physical server. I thought I was typing 'shutdown' into the NoSQL server running on ...
81
votes
12answers
386k views

PuTTY Network Error: Software caused connection abort

I have a strange problem: When I'm using PuTTY with SSH connecting to a Linux server hosted in VMware on my local Windows 7, I often get the error saying "Network error: Software caused ...
80
votes
7answers
594k views

How can I resolve the error “cannot execute binary file”?

When I login using SSH, all I can see is this... -bash: /usr/bin/id: cannot execute binary file -bash: [: : integer expression expected I couldn't do anything in here. Commands such as halt, ...
75
votes
9answers
52k views

How to force GPG to use console-mode pinentry to prompt for passwords?

Using gpg from a console-based environment such as ssh sessions fails because the GTK pinentry dialog cannot be shown in a SSH session. I tried unset DISPLAY but it did not help. The GPG command line ...
71
votes
1answer
23k views

How do I extract fingerprints from .ssh/known_hosts?

My laptop has a well-populated ~/.ssh/known_hosts file. I'd like to leverage that when connecting to remote hosts from my desktop, since tracking down the fingerprints can be a real chore. However, I ...
71
votes
3answers
48k views

Do I need to have a passphrase for my SSH RSA key?

Before I started at my current job (at a small business), my office had no firewall on the network and literally nothing was ever being backed up. Now that I've signed on as a dedicated sysadmin / one-...
70
votes
4answers
35k views

Are GPG and SSH keys interchangable?

I want to generate an RSA key in GPG and use it in SSH login. Is this even possible? If so, how? edit: see @wwerner's answer, I didn't try it but it seems to be the current solution (as of 2018)
67
votes
6answers
209k views

How do I change the colour scheme on PuTTY?

I'm using PuTTY to SSH from my PC at home to Linux computers at work, but some of the text (folder names) is dark blue on black, which is almost impossible to read. How do I change the colour-scheme? ...
67
votes
9answers
155k views

List open SSH tunnels

I use a lot of SSH tunnels to various servers on my linux machine (for tunnelling to databases, web servers etc) and it would be really handy to view a list of current open tunnels via a shell script. ...
66
votes
6answers
95k views

UDP traffic through SSH tunnel

The title pretty much sums it up. I would like to send UDP traffic through a SSH tunnel. Specifically, I need to be able to send UDP packets through the tunnel and have the server be able to send ...
63
votes
6answers
144k views

Downloading Folders to my Local via SSH

I am learning SSH as it seems there are no good SSH GUIs for Macs. I know how to make db dumps, cruise through the directories, etc, but the one last piece of the puzzle I need to learn is how to ...
63
votes
1answer
150k views

How to use X11 forwarding with PuTTY

I have a VM with RHEL 5 without an X server. My host has Windows 7. I need to connect to the VM and redirect the X11 output of the commands to my host. I know that if my host were a GNU/Linux ...
62
votes
3answers
190k views

Command Line SSH restart Mac OSX Mountain Lion

How can I restart the SSH service via the command line on Mac OSX Mountain Lion please? Using ps aux | grep 'ssh', I was able to deduce that the process is most likely /usr/sbin/sshd. From here I ...
61
votes
17answers
37k views

Sharing the same `ssh-agent` among multiple login sessions

Is there a convenient way to ensure that all logins from a given user (ie me) use the same ssh-agent? I hacked out a script to make this work most of the time, but I suspected all along that there ...