I am trying to SSH from one Unix host to another and execute some commands.
Whenever I run ssh hostname <any command> I get back "logname: no login name".
I can succesfully just ssh hostname and then execute the same command without any issues. SSH is setup to use rsa keys for password-less connections.
Everything works fine using a different user account so I suspect it might be related to bash profile or something along those lines? I would appreciate any pointers.
Related
One of my tasks at work is to check the health/status of multiple Linux servers everyday. I'm thinking of a way to automate this task (without having to login to each server everyday). I'm a newbie system admin by the way. Initially, my idea was to setup a cron job that would run scripts and email the output. Unfortunately, it's not possible to send mail from the servers as of the moment.
I was thinking of running the command in parallel, but I don't know how. For example, how can I see output of df -h without logging in to servers one by one.
You can run ssh with the -t flag to open a ssh session, run a command and then close the session. But to get this fully automated you should automate the login process to every server so that you don't need to type the password for every server.
So to run df -hon a remote server and then close the session you would run ssh -t root#server.com "df -h". Then you can process that output however you want.
One way of automating this could be to write a bash script that runs this command for every server and process the output to check the health of the server.
For further information about the -t flag or how you can automate the login process for ssh.
https://www.novell.com/coolsolutions/tip/16747.html
https://serverfault.com/questions/241588/how-to-automate-ssh-login-with-password
You can use ssh tunnels or just simply ssh for this purpose. With ssh tunnel you can redirect the outputs to your machine, or as an alternative, you can run the ssh with the remote commands on your machine then get the ouput on your machine too.
Please check the following pages for further reading:
http://blog.trackets.com/2014/05/17/ssh-tunnel-local-and-remote-port-forwarding-explained-with-examples.html
https://www.google.hu/amp/s/www.cyberciti.biz/faq/unix-linux-execute-command-using-ssh/amp/
If you want to avoid manual login, use ssh keys.
Create a file /etc/sxx/hosts
populate like so:
[grp_ips]
1.1.1.1
2.2.2.2
3.3.3.3
share ssh key on all machines.
Install sxx from package:
https://github.com/ericcurtin/sxx/releases
Then run command like so:
sxx username#grp_ips "whatever bash command"
I want to create a bash script that will login to all the linux servers in my network using ssh and collect the output of 'uptime' command to a local file. There is no keypair installed between these local server and the remote servers. So I need to give the password (username and password is same for all the remote servers) in the script itself. I know this is not a secure way to do it, but it is just for learning purpose. I see 'expect' command can be used for the ssh login with password but confused how to use it together with the 'uptime' command that provide the server status. So my requirement is
1. I have local server test1 which contains a text file 'server_status.txt'
2. I need a script in test1 that will try to login to all the remote servers (say 192.168.0.1 to 192.168.0.50) using the same username and password. It will execute the command 'uptime' once logged in to the remote servers and store the output to the local file 'server_status.txt'
REVOKE: paste your public key into the server's /path2userthatshouldlogon/.ssh/authorized_keys and run the your commands remotely using ssh user#host commandtoexecute
due to connection wanted to be established without key.
UPDATE: have a look at sshpass if you really want to need passwords, which is NOT RECOMMENDED
Note: Doing this is poor practice. If you are testing around with this then you are learning a bad habit. Don't do this in production on servers you care about.
You'll want to execute the expect call as a $? and be sure to store the $USER and $SERVER variables or just replace them:
uptime=$(expect -c 'spawn ssh $USER#$SERVER send "uptime"; exit;')
echo $uptime
i wanted to execute commands on remote linux box from windows and also wanted to collect result of executed command. Basically i have to pass 2 boxes to execute that command here is flow.
Login to a box
ssh to another box
run command
collect output of command locally (in file)
I tried following
F:\xyz>plink xyz#a1.b1.com -i F:\x\y\PRIVATEKEY.ppk -pw xyz
ssh -f root#166.1.8.1 yum upgrade Cyberc
but this is asking for password. I can do it by adding id_rsa.pub value in to authorized_keys but we dont have permission to do. So instead of that i wanted to write EXPECT script to pass user/pass and commands to complete my job.
Any help on EXPECT script would be much appreciated.
Unless the program on the remote linux host is interactive (i.e. it has prompts that the user must respond to), then you probably don't need to use expect - you can simply use plink to connect to the remote Linux host from your windows machine and run the command. You can specify the username and password to authenticate with the remote host in the plink command. See the following links for more info:
http://the.earth.li/~sgtatham/putty/0.58/htmldoc/Chapter7.html
http://stackoverflow.com/questions/12844944/login-syntax-for-plink-using-ip-username-and-password
I'm new to shell scripts, and I have centos running. I want to write a shell script that ssh a remote machine and execute a bunch of commands. The problem I'm facing is how to provide the username, the password, the remote machine address, and the private access key to a command that shall connect the remote machine.
I've Google'd and found some scripts, but all of them need a utility called expect, and I don't want to install any utility, only to run my script. Is there a way to do this?
You can pass all you need in a ssh call, doing the following:
ssh -i private_key_path user_name#remote_machine "command"
If you're going to use this connection many times, and want to maintain it configured, add the following lines to you .ssh/config file:
Host host_alias
User user_name
HostName remote_machine
IdentityFile private_key_path
and then access the remote machine, and execute the command you want, by doing:
ssh host_alias "command"
Notice that command, AFAIK, must be embraced in quotes, as it must be considered as only one argument by ssh.
I know it is possible to write a shell script which passes your hard-coded password to a ssh connection authentication (using expect). However what I need is slightly more complicated.
At my university I have a desktop computer appointed to me. I can connect remotely to this computer by first making a ssh connection with some server, then making another ssh connection from that server to my appointed desktop computer. This goes like:
localuser#localcomputer:~$ ssh -X username#serveraddress
username#serveradress password:
server$ ssh -X username#remotecomputeraddress
username#remotecomputeraddress password:
username#remotecomputer:~>
Is there a way to write a script which could automate the above (i.e. performing two consecutive ssh connections)?
Thanks in advance!
ps: Both the local and the remote computers are running on Linux.
You can do this interactively with:
ssh -t -X username#serveraddress ssh -t -X username#remotecomputeraddress
Note that is not a pipe - the second ssh is the command to run on the connection created by the first ssh. The -t options are necessary to allocate the pseudo-ttys necessary for interaction (password gathering as well as the ultimate goal - an interactive session on the remote system). Wrapping it up with expect left as an exercise for the reader.... ;-)
Bonus points for setting up proper private/public key pairs and ssh-agent so that the passwords aren't necessary (unless, of course, that is disallowed for security reasons).
Yes, you can do this.
Presuming you have your except script in the expect_script:
cat expect_script | ssh -X username#serveraddress sh -s
In this expect_script you must run ssh -X username#remotecomputeraddress.
And of course you can install public keys on the both hosts and use passwordless authentication.
I wrote something to do this with bang paths a while back:
http://stromberg.dnsalias.org/~strombrg/deep-ssh.html
So you'd set up passwordless, passphraseless authentication (or use an agent for the passphrase), like:
http://stromberg.dnsalias.org/~strombrg/ssh-keys.html
And then:
deep-ssh username#serveraddress!username#remotecomputeraddress command
If bash complains about the !, you can just escape it with a backslash.
The old timers will recognize that this is how UUCP paths were specified.