sud

#!/bin/bash

yourDomain='example.com'

case "$1" in
  '' ) echo "Usage: $(basename $0) [hostname|ip]" && exit 1 ;;
  *  ) node="$1"
esac

DNScheck () {
  [ "x$1" = 'x' ] && return 1
  host -t A "$1" | \
  grep -q -e 'has address' -e 'domain name pointer'
}

portOpenCheck () {
  [ "x$1" = 'x' ] && return 1
  timeout 1 bash -c "</dev/tcp/$1/22" &> /dev/null && return 0 || return 1
}

# checkif looks like IP - if not, see if we can resolve
ipregex='([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])'
if [[ $node =~ ^$ipregex\.$ipregex\.$ipregex\.$ipregex$ ]]; then
  DNScheck $node || "will use $node address, but no reverse DNS is setup"
else
  if [[ "$node" == *$yourDomain ]] ; then
    if ! DNScheck $node ; then
      echo "unable to resolve $node" && exit 1
    fi
  else
    if DNScheck $node.$yourDomain ; then
      node=$node.$yourDomain
    else
      if ! DNScheck $node ; then
        echo "unable to resolve $node" && exit 1
      fi
    fi
  fi
fi

while ! portOpenCheck $node ; do
  echo "$(date +'%F %T') | Waiting for $node 22 to become available..."
  sleep 2
done
ssh -t $node 'cat /etc/motd 2>/dev/null ; sudo -i'