#!/bin/bash -x
# sshkeyauth - setup ssh key-based authentication - version 1.0 - July 11
# Copyright 2011 Giuseppe Cuccu, http://www.idsia.ch/~giuse all rights reserved
# Licensed under CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/
# This script is provided AS I USE IT and under constant updating - NO WARRANTY
#
# Configure the variables below and just run the script
#
# User name is supposed to be the same on all servers, as often the case.
# Empty the proxy field to disable port forwarding configuration (VPN SSH tunneling)
#



# VARS TO SET
svlst="salvia.idsia.ch ares.dti.supsi.ch copernicio.idsia.supsi.ch"
proxy="bastion.idsia.ch"
svuser="cuccu"

# DEFAULT VARIABLES
kalgo="dsa"
ksize="1024"
sshconfdir=".ssh"

# AUTOMATIC VARIABLES
privkey="${sshconfdir}/id_${kalgo}"
pubkey="${privkey}.pub"
authkeys="${sshconfdir}/authorized_keys"

# Robustness tweak - ${svlst} is robust to containing or not the proxy
svlst="${svlst//${proxy}/} ${proxy}"

# DEBUG - start from zero
#echo "BEWARE!! YOUR SETTINGS WILL BE ERASED!!" && exit
for sv in ${svlst}; do ssh "${svuser}@${sv}" "rm -rf ${sshconfdir}"; done
rm -rf .ssh
# DEBUG - end


# Generate your keys and add them to ssh-agent
cd ${HOME}
mkdir -m 700 -p ${sshconfdir}
ssh-keygen -t ${kalgo} -b ${ksize} -N "" -f ${privkey}
ssh-add


# If you want to use a proxy, do the same on itand get its key
if [ -n "${proxy}" ]; then
  # proxykey will be not set unless a proxy is provided
  proxykey="${sshconfdir}/proxy.pub"
  ssh "${svuser}@${proxy}" \
    "mkdir -m 700 -p ${sshconfdir} && \
     ssh-keygen -t ${kalgo} -b ${ksize} -N \"\" -f ${privkey} >/dev/null \
     && cat ${pubkey}" > ${proxykey}  # ugly but saves one login
  # note: in my case I didn't need to run ssh-add on the proxy
  #       add the call before the cat if needed
fi


# Add the public key from local machine (and eventually proxy) to all servers
for sv in ${svlst}; do
  cat "${pubkey}" "${proxykey}" | \
    ssh "${svuser}@${sv}" \
      "mkdir -m 700 -p ${sshconfdir} && \
       cat - >> ${authkeys}"
  echo -n "Shared key authentication"
  if [ $? == 0 ]; then echo -n " set "; else echo "\n\t FAILED"; fi
  echo "on server ${sv}"
done


# Recreate ssh configuration file
#./sshconf .ssh/config

echo -e "\n\tDone!\n"