How to set the socket type and the protocol of a socket using create_connection?
Hello everyone,
I want to use socket.create_connection(...) to set a source address in a ping
implementation in python.
But how can I then set the type and the protocol? Because, before, I did:
icmp = socket.getprotobyname("icmp")
my_socket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
But now, I do:
src_addr = socket.gethostbyname(src_addr)
dest_addr = socket.gethostbyname(dest_addr)
my_socket = socket.create_connection(dest_addr, socket.getdefaulttimeout(),
src_addr)
Is there something like my_socket.setproto()? I haven't found such a function
in the documentation.
Thank you,
Guillaume
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Re: How to set the socket type and the protocol of a socket using create_connection?
In fact, socket.create_connection is for TCP only so I cannot use it for a ping implementation. Does anyone have an idea about how to be able to set a source address for ICMP messages? -- http://mail.python.org/mailman/listinfo/python-list
Re: How to set the socket type and the protocol of a socket using create_connection?
Le lundi 20 août 2012 15:38:14 UTC+2, Hans Mulder a écrit : > On 20/08/12 14:36:58, Guillaume Comte wrote: > > > In fact, socket.create_connection is for TCP only so I cannot use it for a > > ping implementation. > > > > Why are you trying to reimplement ping? Because I work on a network emulator and I want to check biterros patterns so I need to access the data of the packets. An dsince my test program is written in Python, it's easier to do it in Python. > > > > All OS'es I am aware of come with a working ping implementation. > > > > > > > Does anyone have an idea about how to be able to set a source address for > > ICMP messages? > > > > Did you try not setting it? > > > > The default is probably your own IP address, which is the only > > sensible value anyway. Or are you trying to cause confusion > > by sending ICMP packets with a forged source address? No, I want to do it on a machine with aliases as in: ifconfig em0 10.0.1.1 netmask 255.255.255.0 alias ifconfig em0 10.0.2.1 netmask 255.255.255.0 alias ping -c4 -S 10.0.1.1 10.0.2.1 But I think I've found the solution: my_socket.bind((src_addr, 1)) > > > > -- HansM -- http://mail.python.org/mailman/listinfo/python-list
Re: How to set the socket type and the protocol of a socket using create_connection?
Unfortunatly, my_socket.bind((src_addr, 1)) doesn't work. I get the error
message: "socket.error: [Errno 49] Can't assign requested address"...
I've tried to change the protocol to IPPROTO_RAW. Here is a simple example of
the code:
import socket
import os
import struct
import time
import select
ICMP_ECHO_REQUEST = 8
PACKET_SIZE = 64 # Bytes
TIMEOUT = 0.5 # Seconds
def do_one(src_addr, dest_addr):
my_socket = socket.socket(socket.AF_INET, socket.SOCK_RAW,
socket.IPPROTO_RAW)
if src_addr != None:
src_addr = socket.gethostbyname(src_addr)
my_socket.bind((src_addr, 1))
my_id = os.getpid() & 0x
print "id: " + str(my_id)
print "sending..."
send_one(dest_addr, my_socket, my_id)
print "receiving..."
id = receive_one(my_socket)
if id == None:
print "nothing received !"
else:
print "received id: " + str(id)
my_socket.close()
def checksum(source_string):
...
def send_one(addr, my_socket, id):
# Header: type (8), code (8), checksum (16), id (16), sequence number (16)
cs = 0
header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, cs, socket.htons(id), 0)
data = PACKET_SIZE * "G"
cs = checksum(header + data)
header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, socket.htons(cs),
socket.htons(id), 0)
packet = header + data
my_socket.sendto(packet, (socket.gethostbyname(addr), 1))
def receive_one(my_socket):
while True:
what_ready = select.select([my_socket], [], [], TIMEOUT)
if what_ready[0] == []:
return None
received_packet = my_socket.recvfrom(1024)[0]
header = received_packet[20:28]
id = struct.unpack("bbHHh", header)[3]
return socket.ntohs(id)
if __name__ == "__main__":
import sys
dst = sys.argv[1]
print "dst: " + dst
try:
src = sys.argv[2]
print "src: " + src
except IndexError:
src = None
do_one(src, dst)
But when I try to set a source address, I still get the same error message...
Does anyone know how I could build the IP header (I don't even know if it can
be the solution but it's worth a try...)?
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Re: How to set the socket type and the protocol of a socket using create_connection?
Le mercredi 22 août 2012 04:10:43 UTC+2, Dennis Lee Bieber a écrit : > On Tue, 21 Aug 2012 10:00:28 -0700 (PDT), Guillaume Comte > > declaimed the following in > > gmane.comp.python.general: > > > > A later follow-up > > > Unfortunatly, my_socket.bind((src_addr, 1)) doesn't work. I get the error > > message: "socket.error: [Errno 49] Can't assign requested address"... > > > > > > > Since .bind() is used to set up a /listener/, the network stack > > (LINK layer) probably has to be tied to the IP address; that is, a valid > > "source" address needs to be supplied to .bind. > Do you mean that an alias is not a valid source address? Because ping.c can do it... I've also tried changing the port to or 8080 but the same error happens. > > > > > > But when I try to set a source address, I still get the same error > > message... > > > > > > Does anyone know how I could build the IP header (I don't even know if it > > can be the solution but it's worth a try...)? > > > > Based upon http://linux.die.net/man/7/raw "Raw sockets allow new > > IPv4 protocols to be implemented in user space. A raw socket receives or > > sends the raw datagram not including link level headers. " implies that > > you need to build the entire IP packet for your ICMP message... That > > means you do NOT use socket methods to set fields -- you'll probably > > have to use something like the struct module to lay out the entire IP > > packet /including/ header contents, and then pass that as-is to the > > socket. > > > > -- > > Wulfraed Dennis Lee Bieber AF6VN > > wlfr...@ix.netcom.comHTTP://wlfraed.home.netcom.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: How to set the socket type and the protocol of a socket using create_connection?
I've managed to build the IP header. I've put the source and destination addresses in this header but it doesn't change the real source address... I'm trying to read the ping source code but I'm lost... -- http://mail.python.org/mailman/listinfo/python-list
Re: How to set the socket type and the protocol of a socket using create_connection?
Le mercredi 22 août 2012 11:03:11 UTC+2, Hans Mulder a écrit : > > On my laptop, 0 appears to be the only port number that bind accepts > > for a raw socket. Other numbers I tried all raise "socket.error: > > [Errno 49] Can't assign requested address". > > > > But this might depend on your OS. What OS are you using? > I'm using FreeBSD 7.3 -- http://mail.python.org/mailman/listinfo/python-list
