#! /bin/sh
## Duplicate DaveG's ident-scan thingie using netcat. Oooh, he'll be p*ssed.
## Args: target port [port port port ...]
## Hose stdout _and_ stderr together.
##
##  Advantages: runs slower than ident-scan, giving remote inetd less cause
##+ for alarm, and only hits the few known daemon ports you specify.
##  Disadvantages: requires numeric-only port args, the output sleazitude,
##+ and won't work for r-services when coming from high source ports.
# Script author: Hobbit <hobbit@avian.org>
# Used in ABS Guide with permission.

# ---------------------------------------------------
E_BADARGS=65       # Need at least two args.
TWO_WINKS=2        # How long to sleep.
THREE_WINKS=3
IDPORT=113         # Authentication "tap ident" port.
RAND1=999
RAND2=31337
TIMEOUT0=9
TIMEOUT1=8
TIMEOUT2=4
# ---------------------------------------------------

case "${2}" in
  "" ) echo "Need HOST and at least one PORT." ; exit $E_BADARGS ;;
esac

# Ping 'em once and see if they *are* running identd.
nc -z -w $TIMEOUT0 "$1" $IDPORT || \
{ echo "Oops, $1 isn't running identd." ; exit 0 ; }
#  -z scans for listening daemons.
#     -w $TIMEOUT = How long to try to connect.

# Generate a randomish base port.
RP=`expr $$ % $RAND1 + $RAND2`

TRG="$1"
shift

while test "$1" ; do
  nc -v -w $TIMEOUT1 -p ${RP} "$TRG" ${1} < /dev/null > /dev/null &
  PROC=$!
  sleep $THREE_WINKS
  echo "${1},${RP}" | nc -w $TIMEOUT2 -r "$TRG" $IDPORT 2>&1
  sleep $TWO_WINKS

# Does this look like a lamer script or what . . . ?
# ABS Guide author comments: "Ain't really all that bad . . .
#+                            kinda clever, actually."

  kill -HUP $PROC
  RP=`expr ${RP} + 1`
  shift
done

exit $?

#  Notes:
#  -----

#  Try commenting out line 30 and running this script
#+ with "localhost.localdomain 25" as arguments.

#  For more of Hobbit's 'nc' example scripts,
#+ look in the documentation:
#+ the /usr/share/doc/nc-X.XX/scripts directory.