ssh to another host and run a command - ssh

I have been able to successfully set-up password-less ssh from host A to host B.
Now I want a script that I run on host A that goes to B and then reads a file or just does something on host B and returns back to A.
On host A:
#!/bin/bash
ssh hostB
echo "$hostname"
ssh hostA
But I just see that this script just lands me on hostB and doesn't perform the echo as I intended it to.
Can someone please suggest what's to be done in such a case? I have gone through some suggestions on using sshpass. But since these are Production hosts, there is a fair bit of paper trail I need to go through to install anything on the hosts and the deadlines are looming to get this fixed.

Answered this question: -
Just needed the following
ssh
Also to note that no $pwd or ./ references hold good on the absolute path . So if there is a script that you are running on the remote host with such references , make sure to change the script so the absolute path is mentioned instead of those references

Related

VScode remote connection error: The process tried to write to a nonexistent pipe

I use vscode with remote-ssh to connect my server, after configuring, I want to connect my host, but it failed, the dialog box display:"could not establish connection to XX, The process tried to write to a nonexistent pipe."
output:
[16:45:20.916] Log Level: 3
[16:45:20.936] remote-ssh#0.49.0
[16:45:20.936] win32 x64
[16:45:20.944] SSH Resolver called for "ssh-remote+aliyun", attempt 1
[16:45:20.945] SSH Resolver called for host: aliyun
[16:45:20.945] Setting up SSH remote "aliyun"
[16:45:21.012] Using commit id "c47d83b293181d9be64f27ff093689e8e7aed054" and quality "stable" for server
[16:45:21.014] Install and start server if needed
[16:45:21.019] Checking ssh with "ssh -V"
[16:45:21.144] > OpenSSH_for_Windows_7.7p1, LibreSSL 2.6.5
[16:45:21.214] Running script with connection command: ssh -T -D 5023 aliyun bash
[16:45:21.221] Terminal shell path: C:\WINDOWS\System32\cmd.exe
[16:45:21.504] >
>
>
> ]0;C:\WINDOWS\System32\cmd.exe
[16:45:21.505] Got some output, clearing connection timeout
[16:45:21.577] >
>
>
>
[16:45:21.592] > Bad owner or permissions on C:\\Users\\DY/.ssh/config
>
[16:45:21.689] > The process tried to write to a nonexistent pipe.
>
[16:45:22.091] "install" terminal command done
[16:45:22.092] Install terminal quit with output: The process tried to write to a nonexistent pipe.
[16:45:22.093] Received install output: The process tried to write to a nonexistent pipe.
[16:45:22.096] Resolver error: The process tried to write to a nonexistent pipe
[16:45:22.107] ------
Add the absolute file path to a custom SSH config file(C:\Users\{USERNAME}\.ssh\config), and my problem is solved.
If you format/re-install Server OS, but use same IP as before,
you may encounter fingerprint mismatched.
You may need to delete old fingerprint in this file:
C:\Users\xxx.ssh\known_host
and old IP in the file:
C:\Users\xxx.ssh\config
Then try to add host again.
What worked for me:
delete ssh config folder both in C:\Program Data\ssh and C:\<user>\.ssh
In VS Code, press F1, choose Remote-SSH: Connect to Host...
Do NOT enter anything in the prompt, but instead choose + Add New SSH Host..
Enter the full ssh command, including the key (in case of Windows,
you may want to enclose the path with double quote mark) ssh -i "C:\path\to\key" user#host. (you need to make sure the key has a limited permission. Remove all inherited permissions, and only give a full control to the owner.)
You will be asked to choose a folder in which a new config file will be created. Choose any of the two options.
There will a prompt notifying that the new config file
has been created. Click connect
At least three things may be happening:
Option 1
The location of your config file is not the absolute location, meaning you are probably using the location of the folder where the config file is.
If that is the case, access your User Settings in VSCode. Scroll to the Extensions>Remote - SSH. And add config at the end of the absolute file path of your custom SSH config file. In Windows, it can be
C:\Users\user\.ssh\config
See image below
Option 2
Authentication problems.
If that is the case, one of the things that may solve is generating new SSH keys.
In Windows, for that, I recommend using MobaXterm.
In MobaXterm, open a new terminal and write
ssh-keygen -b 4096 -t rsa
Then, in the config file, make sure that the IdentityFile points to the location of the key. MobaXterm's home directory, usually, is C:\Users\user\Documents\MobaXterm. If it makes it easy, one can copy/move the keys to C:\Users\user\.ssh and then just add, in the config file, IdentityFile ~/.ssh/KEY_rsa (where KEY_rsa is the name of the [public] key).
Note that if you use PuTTY to generate the keys, on the server OpenSSH authorized_keys file, one doesn't want the public key that one saves, but the one that appears on top (see image bellow):
Option 3
Your config file may be wrong.
The config file tends to look as follows. Double check if the fields have the information needed for the connection to be established.
Host Test # This is the name we want to give the host
User user # This is the username
Hostname blabla.com # This is the hostname
PreferredAuthentications publickey
IdentityFile ~/.ssh/KEY_rsa # This is the location of the key
IdentitiesOnly yes
Port 50 # This varies
What worked for me was to delete all of the contents of folder: C:\Users\MYNAME.ssh That meant to delete both the config file and known-hosts. The config was probably the most important one to delete.
The solution in my case was editing the json settings file for VSC as shown here: https://code.visualstudio.com/docs/remote/troubleshooting#_troubleshooting-hanging-or-failing-connections
In VSC go to File, Preferences, Setting and click on the upper right hand icon (Open Settings, JSON). Add these two lines to settings.json and retry connecting:
"remote.SSH.showLoginTerminal": true,
"remote.SSH.useLocalServer": false
In my case I had another setup:
Git bash in Windows was configured and I am using the ssh.exe provided by this tool
In the "Remote SSH" extension in VSCode, I specified the full path of this ssh.exe
I am using multiple servers (with ProxyJump)
The error message is the same as the OP but in the logs it was written that the ssh config file was not found, where all the folder names was concatenated (because it did not recognize the windows path separator)
Problem: the ssh.exe is using a different path convention thant VSCode. ssh.exe is using the "/c/Users/..." pattern and VSCode is using the "C:\Users..." pattern.
Solution:
Make sure the SSH config is at a standard place (C:\Users\LOGIN\.ssh\config)
Remove the absolute path of the config file in the "Remote SSH" settings in VSCode
VSCode will still be able to access the settings using the standard path, and the ssh.exe configuration will still look at the same standard path so the connexion is working.
Note:
I have the error only when connecting with multiple ssh servers (using ProxyJump). When connecting only to the first server, the solution of #pszrux and this one are both working for me.
This is probably something everyone has tried before looking here, but it worked for me. The server I was trying to ssh into was not responding, leading to the nonexistant pipe error. I rebooted the server and everything worked fine.
OS: windows 10
In my case there were permission issues. Repeatedly changing inheritance in windows did not solve the issue. Finally this worked
change the folder in which the config file is stored.
From C:/users/usr/.ssh/config to D:/config
and changed the config path in vscode remote ssh settings.
This worked for me.
This seems to be a problem with varied causes and corresponding remedies. In my case the problem had to do with the version of ssh I was using. In my Windows path there were two places were an instance of ssh.exe resided:
C:\Program Files (x86)\OpenSSH\bin
C:\WINDOWS\System32\OpenSSH\
After using both paths to set the "Remote.SSH: Path" parameter (which is in "Remote.SSH: Settings" [see here]), i.e. first C:\Program Files (x86)\OpenSSH\bin\ssh.exe and then C:\WINDOWS\System32\OpenSSH\ssh.exe, the problem still persisted.
Then I looked at this and tried the git-provided ssh.exe, which I already had on my system (otherwise, just install git, it's good stuff anyway :) )
Setting the SSH path parameter with that version did the trick for me, i.e. setting path to:
C:\Program Files\Git\usr\bin\ssh.exe
In my case, I did what dalilander said, but instead of deleting the entire '.ssh' folder, I just needed to delete the file 'known_hosts' and then it worked. So the servers I had saved were not deleted.
The path of that folder is C:\Users\yourUsername\.ssh
For Windows:
Adding the escape character before the private key file name & using quotes around the path solved my issue.
//config file
Host 12.12.12.12
HostName 12.12.12.12
IdentityFile "C:\Users\USERNAME/\PRIVATEKEY" <----Note /\
User username
Trying to add the full path in "IdentityFile" made the trick
" IdentityFile C:\Users\xxx.ssh\xxx"
The solution below may be the last resort but it perfectly solved the issue for me in a Windows 10 local machine. I simply delete the known_hosts file under the directory C:\Users\[your-username]\.ssh, relaunch VS Code and reconnect the remote server through Remote Explorer. Everything works normally afterward.
This seems to be a general error when the ssh connection fails for one of a multitude of reasons.
Adding what my issue was, and what helped, because I don't see it in the other answers in here: I had re-installed the box I was connecting to, and with it, reset the key it was using to authenticate. The ssh process tried to connect and failed with the usual "someone might be MITMing you this very moment, the identification changed" error, visible in the VSCode terminal. Solution was to go to my authorized_keys file and remove the offending key.
Obviously only know that if you know for sure why the identification changed, and that it's harmless. Don't actually get MITMed.
I had this problem once.
All you need to do is,
Go to /Users/XXX/.ssh
if you are on the windows, use command : "del /f known_hosts" to delete the known_hosts on the command prompt.
3.Then go to C:\Users\XXX.ssh\config on the vs code( config file )
4.Delete the host and the user if the host that you are trying to connect to is already there.
5.Then try to connect to the new host as usual.This will work.
The problem here could the mismatch of the finger prints once you reinstall the OS o n your host machine.
So to solve this problem by deleting the host that was saved.
once the config file on the vs code is edited it should look like..below picture is to show how the config file should look(after deleting the host saved)
If you're using WSL and might think that you should update ~/.ssh/config, that might not be the case.
Copy the content from ~/.ssh/config
Append it to C:\User\xxx\.ssh\config windows file
Make sure the public/private key is on C:\User\xxx\.ssh\ and is listed in config
Reconnect
Had an existing(working) configuration and had the same error when I added a new one. What worked for me is instead of just adding a new host configuration, I also commented out the first working config. Didn't know what happened but it worked.
In my case this was an offending key in my known_hosts in Windows (vscode on windows, remote developing via ssh on linux).
The error that comes back in vscode is not explaining in any way.
In my case, the path to key file was wrong.
For me, (windows) the permissions on the .pem file were the Critical issue. I had Administrator group only on the pem file and it was not working. I had to explicitly add the Admin user as well (even though admin is of course in administrator group).
In my case, I had no internet connection.
I was connecting to the server via VPN but the remote configuration was incorrect and I couldn't access the server. (DNS related issues) The connection indicator was showing no errors, so I didn't think of that at first.
Oops :)
I really didn't want to delete my C:Users\valo\.ssh\config, so I played a little with the various entries. It turned out that for me the option IdentitiesOnly yes was the problem. I also disabled security inheritance on all key files in the .ssh folder and left only myself, with Full Rights. Here is what my C:Users\valo\.ssh\config looks like now:
CanonicalizeHostname yes
Host aws.r3
HostName 3.31.45.216
ForwardAgent yes
User ubuntu
IdentityFile C:Users\valo\.ssh\u1-client-20210203-090555.pem
# IdentitiesOnly yes # VSCode Remote doesn't like this flag...?
Host github
HostName github.com
User git
IdentityFile ~/.ssh/id_val_ed25519
Host github.vm
HostName github.com
User git
IdentityFile ~/.ssh/id_valo_ed25519
Host *
ForwardAgent yes
AddKeysToAgent yes
LogLevel FATAL
ChallengeResponseAuthentication no
Now I can connect to aws.r3 with VSCode Remote.
A possible solution:
First run cat $HOME/.ssh/id_rsa.pub on your computer. That will get you a key. Save this key somewhere.
Then open this file by running vim $HOME/.ssh/authorized_keys on the computer that you're are ssh'ing to. Then copy the key in a new line of this file and close it by typing :wq.
You are all set.
In my case it was because the name I gave the host in config was myuser#myhostname. So if your config file looks like this:
Host myuser#myhostname
HostName 12.64.88.234
User myuser
Port 22
Try changing it to this:
Host myuser
HostName 12.64.88.234
User myuser
Port 22
Mine was solved by adding ".pem" extension while specifying the private key.
Here's the sample config text for reference.
Host ec2-3-234-8-176.compute-1.amazonaws.com
HostName ec2-3-234-8-176.compute-1.amazonaws.com
IdentityFile ~/.ssh/privatekey.pem
User username
There can be several reasons that have nothing to do with the accepted answer. For me:
Ubuntu 14.04.1 LTS didn't seem to work
Issues with EC2 auth, see pem file config and pem file permissions
And for yet another seeming cause/solution:
Adding the config path explicitly to settings only caused an EISDIR error.
Removing the listing from known_hosts made it need to confirm the fingerprint, but it didn't provide a way to do that. I could see it trying in the terminal output.
The solution a coworker recommended was to delete the vscode-server files from the server. That was the key step in my case. But...
Connecting to the server using another client, I attempted to rm -rf ~/.vscode-server. I could not delete many of the files because "device or resource busy".
That eventually required doing the following:
fuser ~/.vscode-server/[one of the child files ...]. But, you can probably skip this, because mainly I needed to know what to search for. Plus, fuser and lsof were finicky about returning results -- they often just sit waiting for something, I don't know what.
ps -e | grep node since node is the running process using vscode-server files.
For each PID in the list of node processes from step 2, run ps -o user= -p PID, substituting PID with each process PID in turn. This creates a formatted list of the process's associated user.
This is to determine which node processes you own, so you're not even trying to kill anybody else's.
Starting with the lowest node PID I own, run kill -9 PID. You won't need to run this for all PIDs, because killing a lower PID killed a child PID after a few seconds. So keep checking which node processes still exist after killing one: ps -e | grep node
Finally, once all mine are killed, I can rm -rf ~/.vscode-server
Then, I was able to connect via ssh in VS Code again. And, since I left the fingerprint removed from known_hosts, it even asked to confirm the connection to the server (up top, in the command prompt).
Also, for reference, I left the remote-ssh: settings config file entry, mentioned in other solutions, blank.
For reference or further explanation of certain steps above (I don't intend to elaborate more than I did):
rm: cannot remove ‘.vscode-server/bin/xxxxxx/.nfs000000000xxxxxxxxxxxx’: Device or resource busy
How find out which process is using a file in Linux?
https://unix.stackexchange.com/questions/284934/return-owner-of-process-given-pid/284938
In my case it worked when I added the port in my expression, eg ssh user#host-or-ip -p 22. With '22' the default port number, but you can check which port the ssh system is listening on with the sudo service ssh status command.
WSL Related
In my case, the issue was that my keys were set up on Ubuntu on WSL and VS Code was looking for them in Windows. I copied the keys over from the WSL side to Windows and voila! Worked like a charm!
Steps that I took.
Navigated to the /home//.ssh folder in WSL and then entered explorer.exe .
From there, I copied the id_rsa and id_rsa.pub files and pasted them in the windows side, under C:\Users<username>.ssh
Then I tried connecting again from VS Code and it worked perfectly.

How to setup SSH connection with Ansible?

I am brand new to learning Ansible. Here is a pretty easy example.
I have computer A, where I will be running playbooks from.
And 10 other host machines that need to be configured. My question is, do I just need to put the public SSH key of my host machine on the 10 hosts in ~/.ssh/authorized_keys ?
I guess my understanding of how to efficiently setup SSH connections between my main computer and all the clients is a little fuzzy. Any help would be appreciated here.
You create a file called hosts with this content
[test-vms]
10.0.0.100 ansible_ssh_pass='password' ansible_ssh_user='username'
In above hosts file leave off ansible_ssh_pass='password' if using ssh keys ... Then you can create a playbook with the commands and call the playbook like below. The first line of the playbook needs to have the hosts declaration
---
- hosts: test-vms
tasks:
-name: "This is a test task"
command: /bin/hostname
Finally, you call the playbook like this
ansible-playbook -i <hosts-file> <playbook.yaml>
Ansible simply uses SSH so you can either copy the public key as you describe or use password authentication using the --user and --ask-pass flags.
Yes. As far as connection to hosts go, Ansible sets up SSH connection between the master machine and the host machines. You have to add the SSH fingerprints to the end machines. You can always skip the Are you sure you want to continue connecting (yes/no/[fingerprint]) step i.e., adding the fingerprints to .ssh/known_hosts by setting host_key_checking=false
I found this great video for initial Ansible Setup - https://youtu.be/-Q4T9wLsvOQ - maybe this can help!

Ansible ask to verify the ssh fingerprint and fails to ssh into newly created ec2 instance

I am creating ec2 instances and configuring them using ansible scripts. I have used
[ssh_connection]
pipelining=true
in my ansible.cfg file but it still asks to verify the ssh fingerprint, when I type yes and press enter it fails to login to the instance.
Just to let you know I am using ansible dynamic inventory and hence am not storing IPs or dns in hosts file.
Any help will be much appreciated.
TIA
Pipelining doesn't have any effect on authentication - it bundles up individual module calls into one bigger file to transfer over once a connection has been established.
In order not to stop execution and prompt you to accept the SSH key, you need to disable strict host key checking, not enable pipelining.
You can set that by exporting ANSIBLE_HOST_KEY_CHECKING=False or set it in ansible.cfg with:
[defaults]
host_key_checking=False
The latter is probably better for your use case, because it's persistent.
Note that even though this is a setting that deals with ssh connections, it is in the [defaults] section, not the [ssh_connection] one.
==
The fact that when you type yes you fail to log in makes it seem like this might not be your only problem, but you haven't given enough information to solve the rest.
If you're still having connection issues after disabling host key checking, edit the question to add the output of you SSHing into the instance manually, alongside the output of an ansible play with -vvv for verbose output.
First steps to look through when troubleshooting:
What are the differences between when I connect and when Ansible does?
Is the ansible_ssh_user set to the right user for the ec2 instance?
Is the ansible_ssh_private_key_file the same as the private part of the keypair you assigned the instance on creation?
Is ansible_ssh_host set correctly by whatever is generating your dynamic inventory?
I think you can find the answer here: ansible ssh prompt known_hosts issue
Basically, when you run ansible-playbook, you will need to use the argument:
ANSIBLE_HOST_KEY_CHECKING=False
Make sure you have your private key added (ssh-add your_private_key).

Jenkins won't use SSH key

I'm sorry to have to ask this question, but I feel like I've tried every answer so far on SO with no luck.
I have my local machine and my remote server. Jenkins is up and running on my server.
If I open up terminal and do something like scp /path/to/file user#server:/path/to/wherever then my ssh works fine without requiring a password
If I run this command inside of my Jenkins job I get 'Host Key Verification Failed'
So I know my SSH is working correctly the way I want, but why can't I get Jenkins to use this SSH key?
Interesting thing is, it did work fine when I first set up Jenkins and the key, then I think I restarted my local machine, or restarted Jenkins, then it stopped working. It's hard to say exactly what caused it.
I've also tried several options regarding ssh-agent and ssh-add but those don't seem to work.
I verified the local machine .pub is on the server in the /user/.ssh folder and is also in the authorized keys file. The folder is owned by user.
Any thoughts would be much appreciated and I can provide more info about my problem. Thanks!
Update:
Per Kensters suggestion I did su - jenkins, then ssh server, and it asked me to add to known hosts. So I thought this was a step in the right direction. But the same problem persisted afterward.
Something I did not notice before I can ssh server without password when using my myUsername account. But if I switch to the jenkins user, then it asks me for my password when I do ssh server.
I also tried ssh-keygen -R server as suggested to no avail.
Try
su jenkins
ssh-keyscan YOUR-HOSTNAME >> ~/.ssh/known_hosts
SSH Slaves Plugin doesn't support ECDSA. The command above should add RSA key for ssh-slave.
Host Key Verification Failed
ssh is complaining about the remote host key, not the local key that you're trying to use for authentication.
Every SSH server has a host key which is used to identify the server to the client. This helps prevent clients from connecting to servers which are impersonating the intended server. The first time you use ssh to connect to a particular host, ssh will normally prompt you to accept the remote host's host key, then store the key locally so that ssh will recognize the key in the future. The widely used OpenSSH ssh program stores known host keys in a file .ssh/known_hosts within each user's home directory.
In this case, one of two things is happening:
The user ID that Jenkins is using to run these jobs has never connected to this particular remote host before, and doesn't have the remote host's host key in its known_hosts file.
The remote host key has changed for some reason, and it no longer matches the key which is stored in the Jenkins user's known_hosts file.
You need to update the known_hosts file for the user which jenkins is using to run these ssh operations. You need to remove any old host key for this host from the file, then add the host's new host key to the file. The simplest way is to use su or sudo to become the Jenkins user, then run ssh interactively to connect to the remote server:
$ ssh server
If ssh prompts you to accept a host key, say yes, and you're done. You don't even have to finish logging in. If it prints a big scary warning that the host key has changed, run this to remove the existing host from known_hosts:
$ ssh-keygen -R server
Then rerun the ssh command.
One thing to be aware of: you can't use a passphrase when you generate a key that you're going to use with Jenkins, because it gives you no opportunity to enter such a thing (seeing as it runs automated jobs with no human intervention).

cp: cannot create regular file ‘Users/James/Desktop’: No such file or directory

I'm trying to copy a file from a remote server to my desktop and i'm getting the above error. I've SSH'd to the server.
Here is what i'm doing:
deploy#ip-10-91-135-76 /data/project/current/lib/data $ scp customer_record.ods /Users/James/Desktop
I have very limited experience and don't understand what is going on?
Thanks a lot
man scp tells you how to use scp. In particular, most usages look like:
scp [user1#]host1:]file1 [[user2#]host2:]file2
You can omit putting the user in if its the same as your current user, and likewise for the host. Since you've SSH'd onto the server already, the start of your command is okay to be scp customer_records.ods, but the next argument has to include the user name and host of the target machine that you want to copy the file to, namely your home computer. Chances are you actually want to go the other way, since your home computer may not have a publicly accessible IP.
End the SSH session, go back to your home machine.
Do:
scp <user-you-sshd-as>#<server-you-sshd-to>:/data/project/current/lib/data/customer_records.ods /Users/James/Desktop
If you need to specify a private key, you can use the -i option: scp -i <path-to-key> ...