Zjisteni IP pres telnet

README.md

Pouziti

nc (netcat)

martin@martin:~$ nc ip.vancl.eu 1234
77.78.90.200
martin@martin:~$

Busybox telnet client (OpenWrt, Ubiquity)

martin@martin:~$ /bin/busybox telnet ip.vancl.eu 1234
77.78.90.200
Connection closed by foreign host
martin@martin:~$ 

wget

martin@martin:~$ wget http://ip.vancl.eu:1234/ -qO -
77.78.90.200
martin@martin:~$

martin@martin:~$ wget ip.vancl.eu:1234 -qO -
77.78.90.200
martin@martin:~$

Ubuntu telnet client

martin@martin:~$ telnet ip.vancl.eu 1234
Trying ip.vancl.eu...
Connected to ip.vancl.eu.
Escape character is '^]'.
77.78.90.200
Connection closed by foreign host.
martin@martin:~$

Spusteni serveru/kompilace

Spusteni z pythonu

$ python getip.py

Kompilace

$ cython --embed getip.py 
$ gcc getip.c -I/usr/include/python2.7 -lpython2.7 -o getip
$ strip getip
$ du -sh getip
59K	getip
$ file getip
getip: ELF 64-bit LSB  executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=12166ba5208e49ff66eb73820025b860baedc78b, stripped
$
$ ./getip
Using TCP port 1234.

getip.py

import socket
import thread
import sys

# --------------------
port = 1234
host = '0.0.0.0'
# --------------------


print("Using TCP port %s." % (port))
buf = 1024
addr = (host, port)
NL = '\r\n'

serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serversocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
serversocket.bind(addr)
serversocket.listen(500)

clients = [serversocket]

def handler(clientsocket, clientaddr):
    print("Accepted connection from: ", clientaddr)
    clientsocket.settimeout(2)
    try:
        data = clientsocket.recv(buf)
        if "GET" in data or "Host:" in data or "User-Agent" in data: # HTTP request
            clientsocket.send("HTTP/1.0 200 OK" + NL)
            clientsocket.send("Content-type: text/plain; charset=us-ascii" + NL)
            clientsocket.send("Connection: close" + NL)
            clientsocket.send(NL)
            clientsocket.send(str(clientaddr[0]) + NL)

    except socket.timeout: # Telnet request
        clientsocket.send(str(clientaddr[0]) + NL)

    except socket.error: # error
        print("Send to %s error: " % clientaddr)

    finally:
        clients.remove(clientsocket)
        clientsocket.close()

while True:
    try:
        #print("Server is listening for connections\n")
        clientsocket, clientaddr = serversocket.accept()
        clients.append(clientsocket)
        thread.start_new_thread(handler, (clientsocket, clientaddr))
    except KeyboardInterrupt: # Ctrl+C # FIXME
        print("Closing server socket...")
        serversocket.close()

getip_start

#!/bin/bash

while true; do
	/usr/local/bin/getip
	sleep 2
done

#  /usr/local/bin/getip_start 

rc.local

root@server:/home/martin# cat /etc/rc.local 
#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# ...

nohup su - XXX -c "/usr/local/bin/getip_start" &
# XXX je jmeno nejakeho ne-root uzivatele, pod kterym to pobezi

# ...

exit 0