Send UDP packets from any custom port (using libnet). Used for UDP hole punching on linux servers (when the local UDP port is being used).

sendudp.py

#!/usr/bin/env python
#encoding: utf-8
import libnet
from libnet.constants import RAW4, RESOLVE, IPV4_H, UDP_H, IPPROTO_UDP


IFACE = 'wlan2'  # Sending via the interface.

def sendto(sport, address):
    l = libnet.context(RAW4, IFACE)
    dest_ip = l.name2addr4(address[0], RESOLVE)
    l.build_udp(sp=sport, dp=address[1],
            payload='\x00hehe'

    l.autobuild_ipv4(len=(IPV4_H + UDP_H),
            prot=IPPROTO_UDP, dst=dest_ip)

    l.write()


if __name__ == '__main__':
    sendto(6000, ('vpn.sorz.org', 6001))