connect.bash

#!/usr/bin/env bash
#set -x
# ----------------------------------------------------------------------------------------
#
#  Script: connect.bash
#
# Purpose: Provide an on-screen menu for SSH connections.
#
# History:  9/2017 - Created. Adapted from previous versions writted in Bash and Python.
#           2/2018 - Updated to use bash builtin exec to execute ssh commands so that
#                    become its own process independent of this script.
#           3/2018 - Expanded width of menu to fit longer menu names.
#          12/2020 - Added ability to print user's RSA Token passcode via stoken.
#
# ----------------------------------------------------------------------------------------

# ---------------------------------------------------------------------------------------- 
# Define the configuration file
# ----------------------------------------------------------------------------------------
VERSION='1.3.1'
CONFIGFILE=~/.sshconnectrc
NETSTAT=$(which netstat)

# ---------------------------------------------------------------------------------------- 
# Function: add_entry - Provides a series of prompts for adding a connection entry to the
# config file.
# ---------------------------------------------------------------------------------------- 
add_entry ()
{
   echo " * Adding entry to $(echo $CONFIGFILE)..."
   read -rep "Connection Name: " connname
   read -rep "Username: " username
   read -rep "Hostname: " hostname
   read -rep "Hostname for port forwarding: " pfhostname
   read -rep "Port to use: " portnum
   nlines=$(cat $HOME/.sshconnectrc | wc -l)
   nlines=$(($nlines+1))
   if [ -z $pfhostname ]; then pfhostname=$hostname; fi
   echo "$nlines:$connname:$username:$hostname:$pfhostname:$portnum" >> $CONFIGFILE
   read -rep "Do you want to add another entry? [y|n]: " response
   case $response in
      [Yy]*) add_entry ;;
      [Nn]*) ;;
          *) ;;
   esac
}

# ---------------------------------------------------------------------------------------- 
# Function: check_port - to check if a port is open and listening. This function returns
#                        0 is the port is open and listening and 1 otherwise.
# ---------------------------------------------------------------------------------------- 
check_port ()
{
   if [ ! -x $NETSTAT ]; then
      echo " * error: netstat not found."
      exit 1
   fi
   if [[ $(uname -s) == "Darwin" ]]; then
      # FreeBSD or macOS
      $NETSTAT -anp tcp 2>/dev/null | grep LISTEN | grep $portnum 1> /dev/null 2>&1
   elif [[ $(uname -s) == "Linux" ]]; then
      # GNU Linux
      $NETSTAT -tulpn 2>/dev/null | grep LISTEN | grep $portnum 1> /dev/null 2>&1
   fi
   echo $?
}
# ---------------------------------------------------------------------------------------- 
# Function: print_menu - Print the on-screen menu of connection entries
# ---------------------------------------------------------------------------------------- 
print_menu ()
{
   clear
   echo ""
   echo "**************************************"
   echo "*        SELECT HOST COMPUTER        *"
   echo "*               ****                 *"
   while read -r line
   do
      num=$(echo "$line" | cut -d":" -f 1)
      con=$(echo "$line" | cut -d":" -f 2 | sed 's/\"//g')
      printf "* %2d) %-30s *\n" $num "$con"
   done < $CONFIGFILE
   echo "*                                    *"
   echo "*  A) Add entry                      *"
   echo "**************************************"
}

# ---------------------------------------------------------------------------------------- 
# Main Script
# ---------------------------------------------------------------------------------------- 
if [ ! -f $CONFIGFILE ]; then
   echo " * Creating $(echo $CONFIGFILE) ..."
   touch $CONFIGFILE
   add_entry
else
   if [ $(cat $CONFIGFILE | wc -l) -eq 0 ]; then
      add_entry
   fi
fi

print_menu
read -rep "Select option: " selection

if [[ $selection == "A" ]]; then
   add_entry
else
   line=$(grep ^$selection $CONFIGFILE)
   user=$(echo $line | cut -d":" -f 3)
   host=$(echo $line | cut -d":" -f 4)
   porthost=$(echo $line | cut -d":" -f 5)
   portnum=$(echo $line | cut -d":" -f 6)
   usestoken=$(echo $line | cut -d":" -f 7)

   # Check for blank string in ~/.sshconnectrc
   if [ "x$usestoken" == "x" ]; then usestoken=false; fi

   port_in_use=$(check_port)
   if [ $port_in_use -eq 0 ]; then
      # Port is in use
      exec ssh $user@$host
   elif [ $port_in_use -eq 1 ];then
      # Port NOT in use, so port forward here
      echo " * Port $portnum is available..."
      echo " * Connecting to $host binding port $portnum..."
      if [ -f $HOME/.stokenrc ] && [ -x $(which stoken) ] && \
         [ "$usestoken" == "true" ] ; then
         echo " * RSA Token Passcodes: current: $(stoken) next: $(stoken --next)"
      fi
      sshportfwd="-4 -L $portnum:$porthost:22"
      exec ssh $sshportfwd $user@$host
   fi
fi

exit 0