I tried to do game(actually at least to run it on my computer) that I saw in one tutorial. Unfortunately, their forum is not frequently visited, so maybe here I can found the solution.
But when I try to run it on different computers, which are connected to one Wi-fi, client on the second computer(local server is on the first) doesn't find server:
I do this way:
Start server and set to localhost:8000
Start the first client and type localhost:8000, after what it connects to server
In cmd type ipconfig, find IPv4,
Start the second client, and type [IPv4]:8000, but it isn't connecting to server
What have I to do, to make it work?
Here are my code samples:
Client
Server
If it is needed, I can also share PodSixNet files too.
After investigationg with you in the comments, it's clear now that your server is running on the local loopback (i.e. 127.0.0.1), therefore you can't access it from another interface (e.g. [IPv4]).
When you run server, you should set it to 0.0.0.0:8000 (which means all interfaces, port 8000) instead of localhost:8000.
Related
I'll try be concise, but please let me know if I can provide any more helpful pieces of information.
I have client and server Python programs, and they work fine when ran on the same machine, and when the client connects to my machine's local IP (not 127.0.0.1, but the IP assigned to my machine). I have not been able to get this to work with my public IP.
I get a [Errno 61] Connection refused error when I try to get the client to connect to my router's public IP address. My server binds to all interfaces using bind(("0.0.0.0", 50000)), and I already set up port forwarding for my router. I verified that the program is listening on that port by running netstat -an | grep LISTEN and finding the following line:
tcp4 0 0 *.50000 *.* LISTEN
I can also seemingly reach the port through an online port checking tool, which shows that the port is open when I am running my program, and closed when I close that program. My program also registers the connection from this tool.
The fact that my program accepts the connection from the port checking tool gives me the impression that my client code is missing something, but I can't find any answers. It might be worth noting that I am still running my server and client code on the same machine, but I'm not sure why that would derail things. Here's the code I use to connect on the client side:
tcp_client = socket.socket(family=socket.AF_INET, type=socket.SOCK_STREAM)
tcp_client.connect(('my_public_ip', 50000))
Are there any diagnostic steps that I can follow to narrow down my issue?
Before you spend any more time on this, try connecting to your public ip from a computer outside your home network. Spend a couple of dollars on an AWS instance for an hour if you have to, or try connecting from a friend's machine, whatever. It will probably work just fine.
I suspect the problem is simply that you cannot, from inside your home network, connect to your router's public ip address. I tried the same thing with my local network and ran into the same behavior.
If you really need to your public ip during development, you can just assign that as an alias to one of your local interfaces (ip addr add 1.2.3.4/32 dev eth0)...but it's probably easier just to use your an address on your local network, or just arrange for regular access to a remote system for testing.
I'm running a temporary Django app on a host that has lots of IP addresses. When using manage.py runserver 0.0.0.0:5000, how can the code see which of the many IP addresses of the machine was the one actually hit by the request, if this is even possible?
Or to put it another way:
My host has IP addresses 10.0.0.1 and 10.0.0.2. When runserver is listening on 0.0.0.0, how can my application know whether the user hit http://10.0.0.1/app/path/etc or http://10.0.0.2/app/path/etc?
I understand that if I was doing it with Apache I could use the Apache environment variables like SERVER_ADDR, but I'm not using Apache.
Any thoughts?
EDIT
More information:
I'm testing a load balancer using a small Django app. This app is listening on a number of different IPs and I need to know which IP address is hit for a request coming through the load balancer, so I can ensure it is balancing properly.
I cannot use request.get_host() or the request.META options, as they return what the user typed to hit the load balancer.
For example: the user hits http://10.10.10.10/foo and that will forward the request to either http://10.0.0.1/foo or http://10.0.0.2/foo - but request.get_host() will return 10.10.10.10, not the actual IPs the server is listening on.
Thanks,
Ben
request.get_host()
https://docs.djangoproject.com/en/dev/ref/request-response/#django.http.HttpRequest.get_host
but be aware this can be cheated so don't relay your security on it.
If users are seeing your machine under same address I am not sure if this is possible via runserver (it is supposed to be simple development tool).
Maybe you could use nginx?
Or if this is only for testing do something like:
for i in 1 2 3 4 5; do manage.py runserver 10.0.0.$i:5000; done
and then sys.args[2] is your address
If your goal is to ensure the load balancer is working correctly, I suppose it's not an absolute requirement to do this in the application code. You can use a network packet analyzer that can listen on a specific interface (say, tcpdump -i <interface>) and look at the output.
What's the easiest way to establish an emulated TCP connection over HTTP with python 2.7.x?
Server: a python program on pythonanywhere (or some analogue) free hosting, that doesn't provide a dedicated ip. Client: a python program on a Windows PC.
Connection is established via multiprocessing.BaseManager and works fine when testing both server and client on the same machine.
Is there a way to make this work over HTTP with minimal additions to the code?
P.S. I need this for a grid computing project.
P.P.S. I'm new to python & network & web programming, started studying it several days ago.
Found this: http://code.activestate.com/recipes/577643-transparent-http-tunnel-for-python-sockets-to-be-u/. Appears to be exactly what I need, though I don't understand how to invoke setup_http_proxy() on server/client side. Tried setup_http_proxy("my.proxy", 8080) on both sides, but it didn't work.
Also found this: http://docs.python.org/2/library/httplib.html. What does the HTTPConnection.set_tunnel method actually do? Can I use it to solve the problem in question?
Usage on the client:
setup_http_proxy("THE_ADRESS", THE_PORT_NUMBER) # address of the Proxy, port the Proxy is listening on
The code wraps sockets to perform an initial HTTP CONNECT request to the proxy setup to get an HTTP Proxy to proxy the TCP connection for you but for that you'll need a compliant proxy (most won't allow you to open TCP connections unless it's for HTTPS).
HTTPConnection.set_tunnel basically does the same thing.
For your use case, a program running on free hosting, this just won't work. Your free host probably will only allow you to handle http requests, not have long running processes listen for tcp connections(which the code assumes).
You should rethink your need to tunnel and organize your communication to post data (and poll for messages from the server, unless they're answers to the stuff you post). Or you can purchase a VPS hosting that will give you more control over what you can host remotely.
I am running a Graphite server to monitor instruments at remote locations. I have a "perpetual" ssh tunnel to the machines from my server (loving autossh) to map their local ports to my server's local port. This works well, data comes through with no hasstles. However we use a flaky satellite connection to the sites, which goes down rather regularly. I am running a "data crawler" on the instrument that is running python and using socket to send packets to the Graphite server. The problem is, if the link goes down temporarily (or the server gets rebooted, for testing mostly), I cannot re-establish the connection to the server. I trap the error, and then run socket.close(), and then re-open, but I just can't re-establish the connection. If I quit the python program and restart it, the connection comes up just fine. Any ideas how I can "refresh" my socket connection?
It's hard to answer this correctly without a code sample. However, it sounds like you might be trying to reuse a closed socket, which is not possible.
If the socket has been closed (or has experienced an error), you must re-create a new connection using a new socket object. For this to work, the remote server must be able to handle multiple client connections in its accept() loop.
For a class project I'm trying to do some socket programming Python but running into a very basic issue. I can't create a TCP connection from my laptop to a lab machine. (Which I'm hoping to use as the "server") Without even getting into the scripts I have written, I've been simply trying interpreter line commands with no success. On the lab machine (kh4250-39.cselabs.umn.edu) I type the following into Python:
from socket import *
sock = socket()
sock.bind(('', 8353))
sock.listen(5)
sock.accept()
And then on my laptop I type:
from socket import *
sock = socket()
sock.connect(('kh4250-39.cselabs.umn.edu', 8353))
At which point both machines block and don't do anything until the client times out or I send a SIGINT. This code is pretty much exactly copied from examples I've found online and from Mark Lutz's book Programming Python (using '' for the server host name apparently uses the OS default and is fairly common). If I run both ends in my computer and use 'localhost' for the hostname it works fine, so I suspect it's some problem with the hostnames I'm using on one or both ends. I'm really not sure what could be going wrong on such a simple example. Does anyone have an idea?
A good way to confirm whether it's a firewall issue or not is to perform a telnet from the command-line to the destination host in question:
% telnet kh4250-39.cselabs.umn.edu 8353
Trying 128.101.38.44...
And then sometime later:
telnet: connect to address 128.101.38.44: Connection timed out
If it just hangs there at Trying and then eventually times out, chances are the connection to the remote host on that specific port is being blocked by a firewall. It could either be at the network layer (e.g. a real firewall or a router access-list) or at the host, such as iptables or other host-based filtering mechanisms.
Access to this lab host might only be available from within the lab or the campus network. Talk with your professor or a network administrator or someone "in the know" on the network to find out for sure.
Try to bind the server to 'kh4250-39.cselabs.umn.edu' instead of '':
sock.bind(('kh4250-39.cselabs.umn.edu', 8353))
If this does not work: Another reason could be a firewall blocking the port 8353....