I have a script which starts an ssh-connection.
so the variable $ssh start the ssh connection.
so $SSH hostname gives the hostname of the host where I ssh to.
Now I try to echo something and copy the output of the echo to a file.
SSH="ssh -tt -i key.pem user#ec2-instance"
When I perform a manual ssh to the host and perform:
sudo sh -c "echo 'DEVS=/dev/xvdbb' >> /etc/sysconfig/docker-storage-setup"
it works.
But when I perform
${SSH} sudo sh -c "echo 'DEVS=/dev/xvdb' > /etc/sysconfig/docker-storage-setup"
it does not seem to work.
EDIT:
Also using tee is working fine after performing an ssh manually but does not seem to work after the ssh in the script.sh
The echo command after an ssh of the script is happening on my real host (from where I'm running the script, not the host where I'm performing an ssh to). So the file on my real host is being changed and not the file on my host where I've performed an ssh to.
The command passed to ssh will be executed by the remote shell, so you need to add one level of quoting:
${SSH} "sudo sh -c \"echo 'DEVS=/dev/xvdb' > /etc/sysconfig/docker-storage-setup\""
The only thing you really need on the server is the writing though, so if you don't have password prompts and such you can get rid of some of this nesting:
echo 'DEVS=/dev/xvdb' | $SSH 'sudo tee /etc/sysconfig/docker-storage-setup'
Related
I'm trying to run a script on a remote server with either password credentials or .pem key access and I'm getting errors no matter which solution I've found etc.
bash script content:
#!/bin/bash
sudo fdisk -l
ssh -T -i "~/.ssh/keys/key.pem" ubuntu#host "sudo bash <(wget -qO- http://host.com/do.sh)"
Error: bash: /dev/fd/63: No such file or director
ssh user#host.com 'echo "password" | sudo bash <(wget -qO- http://www.host.io/do.sh)'
Error: sudo: a password is required
ssh -t user#host.com "echo password | sudo fdisk -l"
Works but still gives me the password propmt
echo -t pass | ssh user#host "sudo bash <(wget -qO- http://host.com/do.sh)"
echo -tt pass | ssh user#host "sudo bash <(wget -qO- http://host.com/do.sh)"
Error: bash: /dev/fd/63: No such file or directory
// And I also get the password prompt
echo -tT pass | ssh user#host "sudo bash <(wget -qO- http://host.com/do.sh)"
Error: sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
sudo: a password is required
// And I also get the password prompt
// This works but I still get the password propmt
ssh user#host 'echo "password" | sudo -S sudo fdisk -l'
These are different variations of the supposed solutions from other places.
What I'm trying to do:
Is to run a script from a URL on the remote server while echoing the password to the cmd so I don't get propmt to input the password manually.
To be able to do the same thing above with using the .pem key variant also
For an explanation for commands except the first one, You can't do stdin-redirect a password to ssh if ssh requires interactively. ssh only allows manual typing if you use a password.
Your first error said that bash can't read a file descriptor. So ssh via ~/.ssh/keys/key.pem works. To run the shell command on the fly,
ssh -T -i "~/.ssh/keys/key.pem" ubuntu#host "curl -fsSL http://host.com/do.sh | sudo bash"
Does your script really need to run with sudo??
If not, then try this:
ssh user#host "curl -s -o do.sh 'http://host.com/do.sh'; source do.sh"
I'm getting incredibly frustrated here. I simply want to run a sudo command on a remote SSH connection and perform operations on the results I get locally in my script. I've looked around for close to an hour now and not seen anything related to that issue.
When I do:
#!/usr/bin/env bash
OUT=$(ssh username#host "command" 2>&1 )
echo $OUT
Then, I get the expected output in OUT.
Now, when I try to do a sudo command:
#!/usr/bin/env bash
OUT=$(ssh username#host "sudo command" 2>&1 )
echo $OUT
I get "sudo: no tty present and no askpass program specified". Fair enough, I'll use ssh -t.
#!/usr/bin/env bash
OUT=$(ssh -t username#host "sudo command" 2>&1 )
echo $OUT
Then, nothing happens. It hangs, never asking for the sudo password in my terminal. Note that this happens whether I send a sudo command or not, the ssh -t hangs, period.
Alright, let's forget the variable for now and just issue the ssh -t command.
#!/usr/bin/env bash
ssh -t username#host "sudo command" 2>&1
Then, well, it works no problem.
So the issue is that ssh -t inside a variable just doesn't do anything, but I can't figure out why or how to make it work for the life of me. Anyone with a suggestion?
If your script is rather concise, you could consider this:
#!/usr/bin/env bash
ssh -t username#host "sudo command" 2>&1 \
| ( \
read output
# do something with $output, e.g.
echo "$output"
)
For more information, consider this: https://stackoverflow.com/a/15170225/10470287
I am trying to write a deployment script which after copying the new release to the server should perform a few sudo commands on the remote machine.
#!/bin/bash
app=$1
echo "Deploying application $app"
echo "Copy file to server"
scp -pr $app-0.1-SNAPSHOT-jar-with-dependencies.jar nuc:/tmp/
echo "Execute deployment script"
ssh -tt stefan#nuc ARG1=$app 'bash -s' <<'ENDSSH'
# commands to run on remote host
echo Hello world
echo $ARG1
sudo ifconfig
exit
ENDSSH
The file gets copied correctly and the passed argument printed as well. But the prompt for the password shows for two seconds then it says "Sorry, try again" and the second prompt shows the text I enter in plain text (meaning not masked) but also does not work if I enter the password correctly.
stefan#X220:~$ ./deploy.sh photos
Deploying application photos
Copy file to server
photos-0.1-SNAPSHOT-jar-with-dependencies.jar 100% 14MB 75.0MB/s 00:00
Execute deployment script
# commands to run on remote host
echo Hello world
echo $ARG1
sudo ifconfig
exit
stefan#nuc:~$ # commands to run on remote host
stefan#nuc:~$ echo Hello world
Hello world
stefan#nuc:~$ echo $ARG1
photos
stefan#nuc:~$ sudo ifconfig
[sudo] password for stefan:
Sorry, try again.
[sudo] password for stefan: ksdlgfdkgdfg
I tried leaving out the -t flags for ssh as well as using -S for sudo which did not help. Any help is highly appreciated.
What I would do :
ssh stefan#nuc bash -s foobar <<'EOF'
echo "arg1 is $1"
echo "$HOSTNAME"
ifconfig
exit
EOF
Tested, work well.
Notes :
for the trick to work, use ssh key pair instead of using a password, it's even more secure
take care of the place of your bash -s argument. Check how I pass it
no need -tt at all
no need sudo to execute ifconfig and better use ip a
I came up with another solution: Create another file with the script to execute on the remote server. Then copy it using scp and in the calling script do a
ssh -t remoteserver sudo /tmp/deploy_remote.sh parameter1
This works as expected. Of course the separate file is not the most elegant solution, but -t and -tt did not work when inlining the script to execute on the remote machine.
I'd like to capture the output of an ssh session. However, I first need to ssh twice (from my local computer to the remote portal to the remote server), then run a command and capture the output.
Doing this line-by-line, I would do:
ssh name#remote.portal.com
ssh remote.server.com
remote.command.sh
I have tried the following:
server=remote.server.com ##define in the script, since it varies
sshoutput=$(ssh -tt name#remote.portal.com exec "ssh -tt ${server} echo \"test\"")
echo $sshoutput
I would expect the above script to echo "test" after the final command. However, the outer ssh prompt just hangs after I enter my command and, once I Ctrl+c or fail to enter my password, the inner ssh session fails (I believe since stdout is no longer printed to screen and I no longer get my password prompt).
If I run just the inner command (i.e., without "sshoutput=$(" to save it as a variable), then it works but (obviously) does not capture output. I have also tried without the "exec".
I have also tried saving the inner ssh as a variable like
sshoutput=$(ssh -tt name#portal myvar=$(ssh -tt ${server} echo \"test\"") && echo $myvar)
but that fails because BASH tries to execute the inner ssh before sending it to the outer ssh session (I believe), and the server name is not recognized.
(I have looked at https://unix.stackexchange.com/questions/89428/ssh-twice-in-bash-alias-function but they simply say "more flags required if using interactive passwords" and do not address capturing output)
Thanks in advance for any assistance!
The best-practice approach here is to have ssh itself do the work of jumping through your bouncehost.
result=$(ssh \
-o 'ProxyCommand=ssh name#remote.portal.com nc -w 120 %h %p' \
name#remote.server.com \
"remote.command.sh")
You can automate that in your ~/.ssh/config, like so:
Host remote.server.com
ProxyCommand ssh name#remote.portal.com nc -w 120 %h %p
...after which any ssh remote.server.com command will automatically jump through remote.portal.com. (Change nc to netcat or similar, as appropriate for tools that are installed on the bouncehost).
That said, if you really want to do it yourself, you can:
printf -v inner_cmd '%q ' "remote.command.sh"
printf -v outer_cmd '%q ' ssh name#remote.server.com "$inner_cmd"
ssh name#remote.portal.com bash -s <<EOF
$outer_cmd
EOF
...the last piece of which can be run in a command substitution like so:
result=$(ssh name#remote.portal.com bash -s <<EOF
$outer_cmd
EOF
)
I have been trying to automatically enter a ssh connection using a script. This previous SOF post has helped me so far. Using one connection works (the first ssh statement). However, I want to create another ssh connection once connected, which I thought could look like this:
#! /bin/bash
# My ssh script
sshpass -p "MY_PASSWORD1" ssh -o StrictHostKeyChecking=no *my_hostname_1*
sshpass -p "MY_PASSWORD2" ssh -o StrictHostKeyChecking=no *my_hostname_2*
When running the script, I get only connected to the my_hostname_1 and the second ssh command is not run until I exit the first ssh connection.
I've tried using an if statement like this:
if [ "$HOSTNAME" = my_host_name_1 ]; then
sshpass -p "MY_PASSWORD2" ssh -o StrictHostKeyChecking=no *my_hostname_2*
fi
but I can't get any commands to be read until I exit the first connection.
Here is a ProxyCommand example as suggested by #lihao:
#!/bin/bash
sshpass -p "MY_PASSWORD2" ssh -o StrictHostKeyChecking=no \
-o ProxyCommand='sshpass -p "MY_PASSWORD1" ssh m_hostname_1 netcat -w 1 %h %p' \
my_hostname_2
You are proxying through the first host to get to the second. This assumes you have netcat installed on my_hostname_2. If not, you'll need to install it.
You can also set this up in your ~/.ssh/config file so you don't need the proxy stuff on the command line:
Host my_hostname_1
HostName my_hostname_1
Host my_hostname_2
HostName my_hostname_2
ProxyCommand ssh my_hostname_1 netcat -w 1 %h %p
However, this is a little trickier with the password handling. While you could put the sshpass here, it's not a great idea to have passwords in plain text. Using key based authentication might be better.
A Bash script is a sequence of commands.
echo moo
echo bar
will run echo moo and wait for it to complete, then run the next command.
You can run a remote command like this:
ssh remote echo moo
which will connect to remote, run the command, and exit. If there are additional commands in the script file after this, the shell which is executing these commands will continue with the next one, obviously on the host where you started the script.
To connect to one host from another, you could in principle do
ssh host1 ssh host2
but the proxy command suggested by #zerodiff improves on several aspects of the experience.