#!/bin/bash
# file: /usr/bin/getownip.
# permissions: chmod a+x, go-w /usr/bin/getownip
#
# get public IP of your router/NAT by using STUN. (c)jOERG
#
# usage:
# getownip [<stunserver> [<port> [<sec wait for answer> [<number of tries>]]]]
#
#
# you REALLY REALLY ought replace next 2 with your own provider's STUN-server!
stunserver=${1:-stun.sipgate.nex} ;# You have to edit anyway, so shame on you...
port=${2:-10000}   ;#...if you dare to be lazy here. I'll get the flames!

t_listen=${3:-2}   ;# seconds to wait for answer on a single UDP-send. default: 2
num_tries=${4:-5}  ;# number of UDP-sends before give up. default: 5

set -u

session=`tr -d -c [:alnum:] < /dev/urandom | dd  bs=16 count=1 2>/dev/null`

for (( ; num_tries > 0; num_tries-- ))  \
do  ip=`(echo -ne '\x00\x01\x00\x08'; \
     echo -n "$session"; \
     echo -ne '\x00\x03\x00\x04\x00\x00\x00\x00'\
    ) \
    | netcat -w ${t_listen} -u ${stunserver} ${port} \
    | od -w4 -t u1 -j 28 -N 4 -A n \
    | sed 's/^  *//g;s/\  */./g'`

    if [ "$ip"  ]
    then
	echo $ip
        exit 0
    else 
        echo -n "." >&2
    fi
done
exit 3