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I have written a C++ program where I would capture the packets on the interfaces. Based on the packet values, I need to install iptables rules on the remote machine.

For installing iptables on remote machine, I have done the following

  1. I have created SSH key pair so that I can login without password
  2. Written a shell script to execute the iptables command

    output=$(ssh $1 "sudo iptables -t nat -A OUTPUT -p tcp -d "$2" --dport "$3" -j DNAT --to-destination "$4":"$5"")
    

    The parameters are passed to the shell script from the C++ program, and I am using system() command to execute in C++.

    As I want to automate the process, this is not useful as this prompts for remote root login password.

  3. While searching in stack overflow, I found one solution which is

    sudo host 'bash -s' < script.sh
    

    This doesn't ask for remote host password but I do not understand how to automate the process i.e. to pass the iptables parameters to a script and then execute that script with the above command in C++.

I have come across libssh library but that's not been updated for some years. So I am not sure whether I can use it or not.

EDIT 1: As the command sudo host 'bash -s' < script.sh is not asking the password, I have passed the values to the above command like

sudo $1 'bash -s' < script.sh $2 $3 $4 $5

I have placed the above line in, say, remote.sh. When I execute directly on terminal like ./remote.sh (all 5 values), its getting executed perfectly. I have verified in the remote machine.

But when I pass ./remote.sh as C++ command using system(), then it is asking for root password again

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