jumpshell

jumpshell

#!/bin/bash
# SSH Menu for bastion servers 
# John Alvero
# 2014 Nov 16
#
# To use, just set the user's shell to this script like so 
# jump:x:100:100::/home/jump:/opt/bin/jumpshell

function valid_host()
{
    local  ip=$1
    local  stat=1

    if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        OIFS=$IFS
        IFS='.'
        ip=($ip)
        IFS=$OIFS
        [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 \
            && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
        stat=$?
    else
        if [[ `echo $1 | grep -P '(?=^.{1,254}$)(^(?:(?!\d+\.)[a-zA-Z0-9_\-]{1,63}\.?)+(?:[a-zA-Z]{2,})$)'` ]]; then
          stat=$?
        fi
    fi
    return $stat
}

/usr/bin/clear
echo -e "\n\n"
echo -e "Welcome to V jump server. Access will be logged. If you arrived here by mistake, kindly CTRL + C now."
echo -e "\n\n"
echo -n "Enter SSH Username: "
read sshusername
echo -n "Enter SSH Host: "
read sshhost

# Validate Username
if ! [ `echo $sshusername | grep '^[-0-9a-zA-Z]*$'` ]
then
  echo "Invalid Username"
  exit 1  
fi

# Validate IP / Host
valid_host $sshhost

if ! [ $? -eq 0 ]
then
  echo "Invalid IP or hostname. Exiting..."
  exit 1
fi

# Now SSH
ssh $sshusername@$sshhost