How to find, in python, server without having it's IP in LAN?
I assume that port will be configured in file so its doesn't have to find port. I tried to search on google but I couldn't find anything useful or that could help me with it.
The server IP will be changing because it will not run constantly on the same computer.
So basically I got app with server that is on random computer in network, and I want to find its IP from another computer.
I would be really thankful for either explanation how to do it or link that could help me to do it.
Not certain if this is what you want to do, I think you want to find the IP of a server by running some python execution on the server?
You could try :
from subprocess import call
call (["ipconfig"])
This will dump the IP config and you can parse out the IP address. This assumes a windows server. You would have to modify the call for your OS.
Updated :
Check this out : TCP Communications or UDP Communications ... it looks like what you are looking for. You will still have the mess of determining the available addresses on the network (arp -a), and testing each one - this would be your client side app. Your server side app, when it receives the right query on the TCP or UDP port, would then determine it's address (ipconfig) and return the value.
Related
I want to build a DSR load balancer for an application I am writing. I wont go into the application because it is irrelevant for this discussion. My goal is to create a simple load balancer that does direct server response for TCP packets. The idea is to receive all packets at the load balancer, then using something like round robin, select a server from a list of available servers which are defined in some config file. The next step would be to alter the packer received and change the destination ip to be equal to the chosen backend server. Finally, the packet will be sent over to the backend server using normal system calls for sending packets. Theoretically the backend server should receive the packet, and send one back to the original requester, and then the requester can communicate directly with the backend server rather than going through the load balancer.
I am concerned that this design will not work as I expect it to. The main question is, what happens when computer A send a packet to IP Y, but receives a packet back in the same TCP stream from a computer at IP X? Will it continue to send packets to IP Y? Or will it switch over to IP X?
So it turns out this is possible, but only halfway so, and I will explain what I mean by this. I have three processes, one which is netcat, used to initiate an tcp request, a second process, the dsr-lb, which receives packets on a certain port, changes the destination ip to a backend server(passed in via command line arg), and forwards it off using raw sockets, and a third process which is a basic echo server. I got this working on a local setup. The local setup consists of netcat running on my desktop, and dsr-lb and echo servers running on two different linux VMs on the desktop as well. The path of the packets was like this:
nc -> dsr-lb -> echo -> nc
When I said it only half works, what I meant was that outgoing traffic has to always go through the dsr-lb, but returning traffic can go directly to the client. The client does not send further traffic directly to the backend server, but still goes through the dsr-lb. This makes sense since the client opened a socket to the dsr-lb ip, and internally still remembers this ip, regardless of where the packet came from.
The comment saying "if its from a different IP, it's not the same stream. tcp is connection-based" is incorrect. I read through the linux source code, specifically the receive tcp packet portion, and it turns out that linux uses source ip, source port, destination ip, and destination port to calculate a hash which is uses to find the socket that should receive the traffic. However, if no such socket matches the hash, it tries again using only the destination ip and destination port and that is how this "magic" works. I have no idea if this would work on a windows machine though.
One caveat to this answer is that I also spun up two remote VMs and tried the same experiment, and it did not work. I am guessing it worked while all the machines were on the same switch, but there might be a little more work to do to get it to work if it goes through different routers. I am still trying to figure this out, but from using tcpdump to analyze the traffic, for some reason the dsr-lb is forwarding to the wrong port on the echo server. I am not sure if something is corrupted, or if the checksum is wrong after changing the destination ip and some router along the way is dropping it or changing it somehow(I suspect this might be the case) but hopefully I can get it working over an actual network.
The theory should still hold though. The IP layer is basically a packet forwarding layer and routers should not care about the contents of the packets, they should just forward packets based on their routing tables, so changing the destination of the packet while leaving the source the same should result in the source receiving any answer. The fact that the linux kernel ultimately resolves packets to sockets just using destination ip and port means the only real roadblock to this working does not really exist.
Also, if anyone is wondering why bother doing this, it may be useful for a loadbalancer in front of websocket servers. Its not as great as a direct connection from client to websocket server, but it is better than a loadbalancer that handles both requests and responses, which makes it more scalable, and more able to run on less resources.
I have built a d3.js dashboard that ties into a tornado websocket. Everything works perfectly locally. I now would like to have the ability to share the websocket with a few friends, nothing production. Is there a way to do this without a big deployment on Heroku or other similar service? I've googled and can't seem to find an answer. Thanks
Not specific to Tornado. This is more of a networking question.
What you want to do is:
Run your server on your computer.
Connect to the internet.
Note down your public IP address.
Give your IP address to your friends.
Certain things you need to take care of:
Run your server on a higher, non-standard port (e.g. 8000 would be good) because ISPs block traffic to port 80 and other standard ports.
The IP address assigned to you by your ISP will most probably be dynamic. That mean, every time you diconnect and reconnect to the internet, your IP address will change.
Turn off your computer's firewall to let in the traffic at whichever port your server is running.
Finally, you'll need to configure port forwarding on your router. What that means is all the incoming HTTP requests will arrive at your router at your public IP address. But your computer where you'll be running your server will have an internal IP address assigned by your router. So, you'll need to forward incoming requests to your computer's internal IP.
So I am currently working on a destination based routing setup, and I'm really new to the world of Linux. I'm mainly trying to get this to work for video, so what I want to do is route any traffic that I specify through my vpn, and keep the rest of the traffic local. I tried to do this with BBC iPlayer, and I ended up reaching a roadblock because nslookup did not yield the server addresses for Akamai, BBC's CDN. I used tcptrack to find all the incoming connections onto my machine, and I sorted it by connection rate, and the top few would end up being the akamai servers. Well, once I figured this out, I am currently trying to automate the process, and I cannot get tcptrack to write to an output file. Does anyone know of a way to get tcptrack to write to a text file or know of a program that would be better suited to my purpose? What I currently do is use the route command and route the server address, both the one that tcptrack gets me and the nslookup address, through to my vpn using the syntax route add (server address) dev tun0. Any help would be appreciated!
Not sure if i understand the context correctly but if you want to direct specific traffic say based on client IP or domain name then this is possible using Akamai.
I've been developing locally on a little ubuntu netbook with xampp for about 7 months. Two weeks ago I got a computer I'd like to use as a server. I've installed the latest Ubuntu distribution and xampp, moved all my files over, and forwarded port 80. I've also got a domain name from dyndns.com which is being updated by a client which runs in my router (a Netgear WGR6154 v8).
Now, when I try to access my server by typing in the address I got from dyndns.com the browser loads until it timesout. I can access everything locally using localhost as the address so I believe xampp is running, just unable to connect with the internet.
In order to be able to view my files over the internet what should I do next?
Thanks to all in advance...
[I'm starting a bounty for the first person to help me get my files successfully online]
You have a combination of issues here, and that is something of a problem. Each issue is complex in an of itself. Here is what I would recommend to get you going for certain.
First verify that you can surf the web from your server. This will confirm that you have a working ethernet interface.
Step 1 make sure that XAMPP, and your files are viewable from your home network. I assume you are using something like 192.168.1.X for your network and perhaps your server is 192.168.1.10
Go to another computer in your house and type http://192.168.1.10/ and see if you can see your files. If you can then you know that the server is properly configured and XAMPP is working.
Then add an entry to your hosts file to resolve yourdnsrecord.com (or whatever your dyndns record is) to your private ip address. Then when you type yourdnsrecord.com into a browser from that computer you should still get your files. This will rule out your server being improperly configured to listen for that domain name.
Next you need to test to see if there is a firewall problem. To simplify this, first remove your home router from the equation. Instead, place your new server directly onto your internet connection. (assuming you can). This way, you do not need to have NAT or firewalls properly configured. Your dyndns name should map to a public IP and your server should then have that IP and be connected directly to the Internet. If you have your server directly connected, and the command ifconfig from the root prompt returns the same public IP address that your dynamic dns record is point to, then it should work.
It will make your life easier if you have an iphone or some other way to test how your network is seen from the Internet.
If your public IP as shown by ifconfig is different than the IP record in your dyndns account, then your dynamic dns update script is broken. manually set the IP, and see if things work.
It is very possible that this will not work. Some ISPs firewall port 80 preventing their subscribers from hosting servers. Once you have your server directly connected to the internet you can test this (even if your dns is not working) by using the public IP address. As root, type ifconfig from the command prompt to get your public ip address. Then type the command tcpdump -i eth? port 80 from the root prompt. eth? needs to be the same interface that you saw had a public IP address from the ifconfig command. usually this is eth0 but it might be wire0 or something like that.
This command will show you all traffic coming on port 80 to your server.
From an iphone (or whatever second Internet connection you have) browse to the IP address that you got from your ifconfig command. If you see something on your server (and it is directly connected to your ISP) then your ISP is not firewalling you.
If you can get to your server, when it is directly connected to the Internet, either by IP address or by DynDNS address, then your ISP is OK and it is time to debug your firewall.
Two things need to work for your firewall to be configured NAT, where the public address that your router gets from your ISP is converted into your private network and a firewall rule which permits that traffic. If you get this far, then you know your firewall is the problem and then it is just a matter of getting its configuration correct. There are far to many home routers to document here, but you usually can find how-to instructions for your router for this task from the manufacturers website (usually it is part of the manual)
If you follow these instructions exactly you will get your system working. Make comments on the process and I will be happy to modify this to make it clearer.
HTH,
-FT
You should make sure your xampp is not listening to only the localhost.
to do so edit your apache configuration file and check and search for Listen directive
you should be able to know also by analysing the output of netstat -a.
After that make sure your router is forwarding properly, using tcpdump would help.
drop me a comment if you need more help.
Cheers
I have a Linux server with multiple ips (so, multiple eth0, eth0:0, eth0:1 etc).
The script I'm trying to start is a php CLI script which is downloading stuff from an another server API, and I would like to change the IP based on different parameters. Once the script is started, I don't need anymore to change the ip OF THAT SPECIFIC script until his end.
Do you have any clue if it is possible to achieve it?
My other solution was to install Xen or OpenVZ and create N different VPS per each IP, but as you can see is definitely a PITA :-)
You don't specify how you connect to the other server, but with sockets you can try socket_bind.
EDIT:
With curl you can try curl_setopt.
CURLOPT_INTERFACE The name of the outgoing network interface to use. This can be an interface name, an IP address or a host name.
I know how to do it in C - you use bind() on your socket before you call connect(), and you bind to the IP address assigned to the desired interface, passing 0 for port. I don't know how to do it in PHP.