jump

#!/bin/bash

opts=hbckn:
bashrc=false
knownhosts=false

function _usage {
  cat << _USAGE_
  `basename $0`: log on to a server through a jump host

  Usage:
    `basename $0` [-$opts] <dns>

  Options:
    -h        you are here
    -b        port $HOME/.bashrc to the target machine (default: $bashrc)
    -c        run necessary config
    -k        remove dns entry from known_hosts file (default: $knownhosts)
    -n <name> name the target machine (used only with \`-b\`)
_USAGE_
}

function setup {
  [ -z $JUMP_HOST ] \
    && echo -n "jump host (config alias or dns): " \
    && read jhost \
    && echo "export JUMP_HOST=$jhost" >> $HOME/.bash_profile

  [ -z $JUMP_USER ] \
    && echo -n "Jump Host Username: " \
    && read juser \
    && echo "export JUMP_USER=$juser">> $HOME/.bash_profile

  [ -z $JUMP_KEY ] \
    && echo -n "absolute path to jump host key: " \
    && read jkey \
    && echo "export JUMP_KEY=$jkey">> $HOME/.bash_profile

  [ -z $JUMP_PORT ] \
    && echo -n "jump port: " \
    && read jport \
    && echo "export JUMP_PORT=$jport">> $HOME/.bash_profile
}

while getopts $opts opt; do
  case $opt in
    h) _usage; exit     ;;
    b) bashrc=true      ;;
    c) setup; exit      ;;
    k) knownhosts=true  ;;
    n) name="$OPTARG"   ;;
    ?|*) _usage; exit 2 ;;
  esac
done

shift $(($OPTIND-1))

[ -z $JUMP_HOST ] && { echo "JUMP_HOST not set (try `basename $0` -c)" >&2; exit 1; }
[ -z $JUMP_USER ] && { echo "JUMP_USER not set (try `basename $0` -c)" >&2; exit 1; }
[ -z $JUMP_KEY ]  && { echo "JUMP_KEY not set (try `basename $0` -c)" >&2;  exit 1; }

: ${JUMP_PORT:=22 }

proxy="ssh -W %h:%p $JUMP_HOST"

[ -z $1 ] && { ssh -p $JUMP_PORT -i $JUMP_KEY $JUMP_USER@$JUMP_HOST; exit; }

$knownhosts && ssh-keygen -R $1

! $bashrc && { ssh -p $JUMP_PORT -i $JUMP_KEY -oProxyCommand="$proxy" $JUMP_USER@$1; exit; }

[ ! -f $HOME/.bashrc ] && { echo "$HOME/.bashrc doesn't exist" >&2; exit 1; }

t=$(mktemp /tmp/jump.bashrc.XXXX)

[ -n "${name#++([[:space:]])}" ] && echo "export HOSTNAME=$name" >> $t
cat $HOME/.bashrc >> $t

scp -p $JUMP_PORT -i $JUMP_KEY -oProxyCommand="$proxy" $t $JUMP_USER@$1:/home/$JUMP_USER/.bashrc \
  && { rm -f $t; ssh -p $JUMP_PORT -i $JUMP_KEY -oProxyCommand="$proxy" $JUMP_USER@$1; }