xssh

#!/bin/bash

# Script written by Daniel Frank
# Purpose:
#       This script tricks SSH into accepting a password through a pipe.
#       1. The script check if the session is connected to a terminal,
#          if yes, the script will restart itself by relogging into the
#               current host through ssh without allocating a pty.
#       2. After the command line is parsed, the password is read from stdin.
#       3. The script sets up a named pipe and exports the name in the
#               environment.
#       4. The script sets the DISPLAY variable to a dummy value.
#       5. The script sets the SSH_ASKPASS variable to point to itself.
#       6. SSH is started, which will execute the SSH_ASKPASS instance of
#               this script.
#       6. The script provides the password to its SSH_ASKPASS instance
#               through the pipe.
#       7. The SSH_ASKPASS instance of the script echoes out the password
#               to SSH.


# if FIFO is set, the script is actually run by SSH as SSH_ASKPASS
if [ -n "$FIFO" ]; then
        cat $FIFO
        exit
fi

# Resolve the path of the script
SCRIPTPATH="$( cd $(dirname $0) ; pwd -P )/$(basename $0)"

if [ "$#" -eq 0 ]; then
        echo "Usage: $0 <USER> <SERVER1> [SERVER2 ...] -- <COMMAND LINE>"
        echo "Example: daniel server1 server2 -- hostname"
        echo " (use four backslashes where you want to have one)"
        exit 1
fi

# If the session the script is running in has a terminal connected to it,
# SSH will not accept the password from a pipe, so we just relogin to
# the current host without a terminal and pass all parameters.
if [ -t 0 ]; then
        ssh -T $LOGNAME@$(hostname) $SCRIPTPATH $@
        exit
fi

# Parse the command line
DOMUSER="$1"
shift
while [ "$#" -gt 0 ]; do
        case "$1" in
                "--")
                        NOMORESERVERS=1
                        ;;
                *)
                        if [ -n "$NOMORESERVERS" ]; then
                                if [ -z "$COMMAND" ]; then
                                        COMMAND="$1"
                                else
                                        COMMAND="$COMMAND $1"
                                fi
                        else
                                if [ -z "$SERVERS" ]; then
                                        SERVERS="$1"
                                else
                                        SERVERS="$SERVERS $1"
                                fi
                        fi
                        ;;
        esac
        shift
done

echo DOMUSER: $DOMUSER
echo SERVERS:  $SERVERS
echo COMMAND: $COMMAND

# Request the password
echo -n Enter your password to execute the command as listed above, cancel with CTRL-C:\
PASS="$(head -1)"

# Loop over all servers
for SERVER in $SERVERS; do
        # Setup a fifo
        FIFO=$(mktemp)
        rm $FIFO; mkfifo $FIFO || exit
        export FIFO
        # DISPLAY has to be set to a dummy value, or SSH will ignore the SSH_ASKPASS variable
        export DISPLAY=dummy:1
        # SSH_ASKPASS points to this script, which will check if the variable FIFO is set
        # and just output the password that comes through the FIFO.
        export SSH_ASKPASS="$SCRIPTPATH"
        echo \### $SERVER: $COMMAND | sed -e 's_._#_g'
        echo \### $SERVER: $COMMAND
        # Run SSH in background so we can pass the password through the FIFO.
        ssh -o StrictHostKeyChecking=yes $DOMUSER@$SERVER $COMMAND &
        # pass the password through the FIFO
        echo "$PASS" > $FIFO
        # Wait until ssh exits
        wait
        # remove the FIFO
        rm $FIFO
done