Programming Forums > Script Programming > Python

Writlaus · Feb 20th, 2006, 5:40 AM

I'm trying to figure out how to have a program connect to another program on a different computer, without a server. Just a direct connection. Can someone point me to a good tutorial for this?

Polyphemus_ · Feb 20th, 2006, 6:10 AM

Google is your friend

:
http://www.amk.ca/python/howto/sockets/

You will always need a server socket, to accept a connection. This doesn't mean you will need a complete server, though.

Sane · Feb 20th, 2006, 9:22 AM

The most secure way, IMO, especially if you're using open-sourced programming (Python), is to go through a server.

I only have experience with the latter though, only small stuff with the socket module, so don't base what I'm saying on any matter. :p

Arevos · Feb 20th, 2006, 9:58 AM

Server-client networking is no more secure than peer-to-peer networking. Transmission security is just a matter of encryption.

Though I suppose you could argue that a well-known server is more trustworthy than an anonymous peer, assuming the peer is anonymous.

Writlaus · Feb 21st, 2006, 6:15 PM

Yes, I know that one of the programs must act as a server; what I meant is no central server on a website somewhere =)

Thanks for the link, polyphemus.

Writlaus · Feb 24th, 2006, 6:57 PM

Anyone good with sockets? I can't seem to get them working. Here's my code...

(Toggle Plain Text)

#Server:

import socket
mySocket=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
mySocket.bind((socket.gethostbyname(socket.gethostname()),3867))
mySocket.listen(1)
while True:
   channel,details=mySocket.accept()
   print 'We have opened a connection with',details
   print channel.recv(100)
   channel.send('Green-eyed monster.')
   channel.close()

(Toggle Plain Text)

#Client

import socket
mySocket=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
mySocket.connect(('[IP address]',3867))#Here I actually put my ip address, not just '[IP address]'.

All I'm trying to do is just get a connection, but I can't. Can anyone help?

EDIT: For some reason it's showing two spaces in the middle of SOCK_STREAM and gethostname(), but those aren't in the code =)

Arevos · Feb 24th, 2006, 7:04 PM

Shouldn't your client be sending something? The "print channel.recv(100)" will wait until the connecting client has sent some data down the stream. If your client doesn't send anything, it will wait forever.

Writlaus · Feb 24th, 2006, 7:05 PM

Right, but my problem is that it's not even printing 'we have a connection with',details; I'm not even getting a connection.

Arevos · Feb 24th, 2006, 7:27 PM

Try changing this line:

(Toggle Plain Text)

mySocket.bind(( socket.gethostbyname(socket.gethostname() ),3867))

To this:

(Toggle Plain Text)

mySocket.bind(('', 3867))

Python's socket module treats a blank string as equivalent to localhost, or 127.0.0.1. So this tells it to bind to the local socket 3867.

On your client side, be aware that if you're behind a NAT, you'll need to talk to your server via it's local IP address (192.168.x.x or 10.x.x.x), or, if it's on the same machine as your server, through localhost (127.0.0.1 or a blank string).

Writlaus · Feb 24th, 2006, 8:15 PM

Well, I'm not trying to connect within the same machine; the Server program is on my computer, but the client is run on a friend's computer. I'm trying to connect across the internet.

Edit: Ah right, I think I read your post wrong. I'll try that.

Feb 20th, 2006, 5:40 AM	#1
Writlaus Hobbyist Programmer Join Date: Nov 2005 Posts: 149 Rep Power: 4	Internet connection I'm trying to figure out how to have a program connect to another program on a different computer, without a server. Just a direct connection. Can someone point me to a good tutorial for this?

Feb 24th, 2006, 6:57 PM	#6
Writlaus Hobbyist Programmer Join Date: Nov 2005 Posts: 149 Rep Power: 4	Anyone good with sockets? I can't seem to get them working. Here's my code... (Toggle Plain Text) #Server: import socket mySocket=socket.socket(socket.AF_INET,socket.SOCK_STREAM) mySocket.bind((socket.gethostbyname(socket.gethostname()),3867)) mySocket.listen(1) while True: channel,details=mySocket.accept() print 'We have opened a connection with',details print channel.recv(100) channel.send('Green-eyed monster.') channel.close() #Server: import socket mySocket=socket.socket(socket.AF_INET,socket.SOCK_STREAM) mySocket.bind((socket.gethostbyname(socket.gethostname()),3867)) mySocket.listen(1) while True: channel,details=mySocket.accept() print 'We have opened a connection with',details print channel.recv(100) channel.send('Green-eyed monster.') channel.close() (Toggle Plain Text) #Client import socket mySocket=socket.socket(socket.AF_INET,socket.SOCK_STREAM) mySocket.connect(('[IP address]',3867))#Here I actually put my ip address, not just '[IP address]'. #Client import socket mySocket=socket.socket(socket.AF_INET,socket.SOCK_STREAM) mySocket.connect(('[IP address]',3867))#Here I actually put my ip address, not just '[IP address]'. All I'm trying to do is just get a connection, but I can't. Can anyone help? EDIT: For some reason it's showing two spaces in the middle of SOCK_STREAM and gethostname(), but those aren't in the code =)

Feb 24th, 2006, 7:27 PM	#9
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	Try changing this line: (Toggle Plain Text) mySocket.bind(( socket.gethostbyname(socket.gethostname() ),3867)) mySocket.bind(( socket.gethostbyname(socket.gethostname() ),3867)) To this: (Toggle Plain Text) mySocket.bind(('', 3867)) mySocket.bind(('', 3867)) Python's socket module treats a blank string as equivalent to localhost, or 127.0.0.1. So this tells it to bind to the local socket 3867. On your client side, be aware that if you're behind a NAT, you'll need to talk to your server via it's local IP address (192.168.x.x or 10.x.x.x), or, if it's on the same machine as your server, through localhost (127.0.0.1 or a blank string).

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Feb 20th, 2006, 6:10 AM	#2
Polyphemus_ Expert Programmer Join Date: Aug 2005 Location: Rotterdam, the Netherlands Posts: 942 Rep Power: 4	Google is your friend : http://www.amk.ca/python/howto/sockets/ You will always need a server socket, to accept a connection. This doesn't mean you will need a complete server, though.

Feb 20th, 2006, 9:22 AM	#3
Sane Banned Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,101 Rep Power: 6	The most secure way, IMO, especially if you're using open-sourced programming (Python), is to go through a server. I only have experience with the latter though, only small stuff with the socket module, so don't base what I'm saying on any matter. :p

Feb 20th, 2006, 9:58 AM	#4
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	Server-client networking is no more secure than peer-to-peer networking. Transmission security is just a matter of encryption. Though I suppose you could argue that a well-known server is more trustworthy than an anonymous peer, assuming the peer is anonymous.

Feb 21st, 2006, 6:15 PM	#5
Writlaus Hobbyist Programmer Join Date: Nov 2005 Posts: 149 Rep Power: 4	Yes, I know that one of the programs must act as a server; what I meant is no central server on a website somewhere =) Thanks for the link, polyphemus.

Feb 24th, 2006, 7:04 PM	#7
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	Shouldn't your client be sending something? The "print channel.recv(100)" will wait until the connecting client has sent some data down the stream. If your client doesn't send anything, it will wait forever.

Feb 24th, 2006, 7:05 PM	#8
Writlaus Hobbyist Programmer Join Date: Nov 2005 Posts: 149 Rep Power: 4	Right, but my problem is that it's not even printing 'we have a connection with',details; I'm not even getting a connection.

Feb 24th, 2006, 8:15 PM	#10
Writlaus Hobbyist Programmer Join Date: Nov 2005 Posts: 149 Rep Power: 4	Well, I'm not trying to connect within the same machine; the Server program is on my computer, but the client is run on a friend's computer. I'm trying to connect across the internet. Edit: Ah right, I think I read your post wrong. I'll try that.

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