ssh-tunnelr.sh

#!/bin/bash

######################
# ssh-tunnelr v2.4.2 #
######################

show_help () {
  echo "Usage: ssh-tunnelr [OPTIONS|SSH OPTIONS] HOST[S] [RANGE] [RANGE...]

  Hosts:                 Hosts separate by ',' e.g. host.domain.com,172.16.1.8,user@10.1.8.1:2222
                         An host is defined by [user@]host[:ssh_port] where user and ssh_port are optional
  Range(s)               Ports to forward to endpoint. This can be a single port e.g. 80 or a range e.g. 80:82.
                         You also can specify output port range with a third port number e.g. 7000:7002:80.
                         So port 7000 will be forwarded on port 80 of the endpoint, 7001 on 81 and 7002 on 82.
                         For single port combined with output port scpecified, you have to write 7000:7000:80.
                         Several ranges are allowed and must be separated by spaces  e.g 10000:10008 7000:7002:80 3306.
  Options:
    -d, --dry            Dry mode, for test. With this option, ssh command is not launched, it's only shown.
    -h, --hide-tunnels   Don't show tunnels in command output. Especially useful when you need large range of ports
                         and your screen is too small.
    -q, --quiet          Quiet mode. Display no output.
    --help               Show help
  
  SSH Options:           These options are passed to each ssh command on each host.
    -t                   Force pseudo-terminal allocation.
    -X                   Enables X11 forwarding.
  
  Example:               ssh-tunnelr foo@host.domain.com,172.16.1.11,bar@10.5.1.10:2222 7000:7008"
}

XFORWARDING=0
PTERMALLOC=0
DRY_MODE=0
HIDE_TUNNELS=0
QUIET=0
MAX_PORT_NUMBER=65535

while :; do
  case $1 in
    -t)
      PTERMALLOC=1
      ;;
    -X)
      XFORWARDING=1
      ;;
    -d|--dry)
      DRY_MODE=1
      ;;
    -h|--hide-tunnels)
      HIDE_TUNNELS=1
      ;;
    -q|--quiet)
      QUIET=1
      ;;
    --help)
      show_help
      exit
      ;;
    -?*)
      printf 'WARN: Unknown option (ignored): %s\n' "$1" >&2
      ;;
    *)
      break
  esac
  shift
done

HOSTS="$1"
shift

for arg in "$@"; do
  RANGES="$RANGES $arg"
done

throw_error () {
  MSG=$1
  EXIT=$2
  STD_MSG="Command stopped"
  printf "\033[0;31m%s\033[0m\n" "$MSG"
  echo "$STD_MSG"
  if $EXIT ; then
    exit 1
  fi
}

# unserialize data
IFS=',' read -r -a HSTS <<< "$HOSTS"
IFS=' ' read -r -a PRS  <<< "$RANGES"

# checks
if (( "${#HSTS[@]}" == 0 )); then
  throw_error "Please specify at least one host"
fi

# construct ssh command
CMD=""
# for each host
for ((i=0; i<${#HSTS[@]}; ++i)); do
  HST=${HSTS[$i]}
  SSH_USER=""
  SSH_PORT=""
  # if ssh user specified
  if [[ "$HST" =~ ^(.+)@(.+)$ ]]; then
    SSH_USER="${BASH_REMATCH[1]}@"
    HST=${BASH_REMATCH[2]}
  fi
  # if ssh port specified
  if [[ "$HST" =~ ^(.+):([0-9]+)$ ]]; then
    HST=${BASH_REMATCH[1]}
    SSH_PORT="-p ${BASH_REMATCH[2]}"
  fi
  # ssh native options
  SSH_OPTIONS=""
  if [ "$PTERMALLOC" -eq "1" ]; then
    SSH_OPTIONS="$SSH_OPTIONS -t"
  fi
  if [ "$XFORWARDING" -eq "1" ]; then
    SSH_OPTIONS="$SSH_OPTIONS -X"
  fi

  CMD="$CMD\nssh $SSH_OPTIONS $SSH_PORT $SSH_USER$HST\n"

  # for each range in ports ranges
  for ((j=0; j<${#PRS[@]}; ++j)); do
    # unserialize range
    IFS=':' read -r -a PR <<< "${PRS[$j]}"

    # if single port specified
    if (( "${#PR[@]}" == 1 )); then
      PR[1]=${PR[0]}
      PR[2]=${PR[0]}
    # single port with out port specified shortcut e.g. 6000::9000
    elif (( "${#PR[@]}" == 3 )) && [[ "${PR[1]}" -eq "" ]]; then
      PR[1]=${PR[0]}
    fi

    SRC_PORT=${PR[0]}
    DST_PORT=${PR[0]}
  
    # if last host AND out ports range specified
    if [[ "$(( i + 1 ))" -eq "${#HSTS[@]}" && "${#PR[@]}" -eq "3" ]]; then
      DST_PORT=${PR[2]}
    fi

    # checks
    if (( SRC_PORT < 1 )) || (( DST_PORT < 1 )); then
      throw_error "Ports numbers  must be greater than 1"
    fi
    if (( PR[0] > PR[1] )); then
      throw_error "First port in range must be less than last port"
    fi

    # for each port in range
    for ((k=PR[0]; k<=PR[1]; ++k)); do
      # checks
      if (( SRC_PORT > MAX_PORT_NUMBER )) || (( DST_PORT > MAX_PORT_NUMBER )); then
        throw_error "Ports numbers  must be less than $MAX_PORT_NUMBER - $DST_PORT"
      fi

      CMD="$CMD-L $SRC_PORT:localhost:$DST_PORT\n"

      (( SRC_PORT++ ))
      (( DST_PORT++ ))
    done
  done
done

OUTPUT=$CMD
OUTPUT_CMD="echo -e \"$OUTPUT\""

if (( HIDE_TUNNELS == 1 )); then
  OUTPUT_CMD="$OUTPUT_CMD| grep -v '\-L\\s'"
fi

# show output
if [ "$QUIET" -eq "0" ]; then
  eval "$OUTPUT_CMD"
fi

CMD="$(echo -e "$CMD")"
if [ "$DRY_MODE" -eq "0" ]; then
  $CMD
fi