I'm using Python 3.8.5 currently on windows, but the script should run also on linux and on macOS.
I'm creating UDP server and a client and have establish communication between them via multicast.
The client does not know from advanced the IP of the server so it is a "discovery tool" that will let me know information about the server ones it has received the data. -This is working-
On the server I'm using netifaces to get information about the interfaces.
The server sends information to the client such as IP address, mask, gateway. -information that I get from netifaces and is working-.
Example of data I get:
Now to the issue:
The python server can have a static IP or can be connected to a DHCP server -in case that is connected to a DHCP server I will not have access to the DHCP server-.
I wish to know when the DHCP is enabled or disable on the python server so I can send this as a flag to the client together with the rest of the information.
The idea is for the client to know that the IP that he's connecting to can change and he may lose connection and will need to start the discovery tool once more.
Because the user will not know in advanced if the python server is connected to a DHCP server or wil know the IP address of the python server or have access to the python server command line or configuration, using ip addr show, ipconfig, ifconfig and other commands before connecting is not an option.
I have seen that people use scrapy for DHCP communications but it seems that it does not solves what I wish to accomplish.
I do no need to configure the DHCP, just detect if my python server IP is static or dynamic.
I have search for over 4 days and have not found a possible solution.
I'm not asking to have the solution in silver spoon just to be pointed on the right direction.
**EDIT: I forgot to mention that the python server will be running on Ubuntu 16.04 and 20.04.
This will depend on your operating system setup. For example, here's a related question on how to detect whether DHCP is enabled in Ubuntu.
Related
I wrote a Python client/server which I was able to test successfully between two devices on the same network; however, the client fails to connect to the server through the public IP. My hunch is that it's a port forwarding issue in that case. I don't want my users to have to manually port forward to use my program. Is there a pythonic way to add inbound rules to Windows Defender Firewall? Alternatively, is there some other simple example of a client/server in Python that works when connecting via public IP address?
Im very new to network programming and faced a following problem:
Im working on VMware CentOS7 virtual machine on Windows10 host.
My script should send WHOIS queries and parse their output (e.g. expiration date).
However, an attempt to send a query leads to a connection error:
>>>import whois
>>>whois.query('google.com')
WhoisCommandFailed: connect: Network is unreachable
I tried to whois from terminal, but error was the same.
When i tried to use whois directly from Windows, which hosts virtual machine, the error seemed to look same as well (connection timeout).
As i found out, it was most likely related to access to port 43. I created rules (for in and out) for Windows firewall for this port by a guide , but error still persisted.
It looks like access to this port was blocked by ISP (however ping command is working).
To sum up, I got two questions there:
1) (less important) How to check if port 43 is blocked by firewall either by ISP?
2) (most important) Is it possible somehow to reconfigure WHOIS for usage of another port (i.e. 23) for sending queries by Python script?
Unfortunately, ISP security policy doesn't allow them to open 43 port.
Mostly ISP doesn't block any port but yes, this is not 100% true.
Testing connection:
run tcpdump (install command: yum install tcpdump) command on CentOS: tcpdump -peni any tcp and port 43
You have to see lines with the following text: 192.168.1.1.57350 > 192.34.234.30.43 where 192.34.234.30 IP address means the remote whois server.
Try to telnet to remote server's TCP/43 port: telnet 192.34.234.30 43
You should see the following:
Trying 192.34.234.30...
Connected to 192.34.234.30.
Escape character is '^]'.
If you can`t see context like that and you get back prompt immediately you will a firewall rule somewhere what is block connection. I recommend to switch off firewall temporarily and test again.
You cannot change port number, because it is configured on the remote side, on the server.
Can CentOS7 server communicate towards the internet? In example can you install packages?
Is there any router between windows machine and ISP?
I've been working on a website for the past month, and now its time for me to host the django website onto a private server. Is there a detailed method on how I'm supposed to host the website onto a specific IP address assigned to my system?
This is my first time dealing with hosting a server and i dont know much about it.
Also, once i host it, How do i change the link from being the IP address to an actual link like "12345678.com" or something like that?
(The website should be hosted in such a way that only the people who are in the same network/lan connection should have access to the website.)
I have wamp on the system and the system has a Windows Server OS (if this info helps)
you can run your codes with manage command like this
python manage.py runserver 0.0.0.0:8000
but its strongly recommended to run your code with a web server like nginx or apache read this tutorial to run your site on a linux server
https://www.digitalocean.com/community/tutorials/how-to-set-up-uwsgi-and-nginx-to-serve-python-apps-on-ubuntu-14-04
on windows you can use IIS but its not recommended. its performance is not good
to use 1234567890.com instead of using server ip address you must setup a DNS server on your local network. in linux you can use bind and windows server have its own DNS server. but in your DHCP configuration you must set this DNS server as clients DNS.
I have written a server program using python and django and I have tested it in several computers. Now I have installed it on a HP server. While I can see that it is working when I type localhost in browser address, when I type the server's IP, I see "This webpage is not available" (ERR_CONNECTION_REFUSED).
The OS is windows server 2008. There isn't any antivirus or firewall installed and the windows firewall is disabled.
It's noticeable that the messages that I send from my server program to some other devices in the network are successfully delivering. In the other word the connection is one-way (not duplex)
Assuming you're using the Django development server:
To make your development server viewable to other machines on the
network, use its own IP address (e.g. 192.168.2.1) or 0.0.0.0 or ::
(with IPv6 enabled).
So, your command will look something like
runserver 0.0.0.0:8000
There have been a few questions like this around the place but none have really answered my question specifically.(for example Connecting to device behind firewall )
What I want is a central server, that receives a heartbeat from multiple ( say 100's) embedded devices behind personal firewalls. These devices need to be able to do two things.
Grab new config from the server. I
suspect I can just do this via a
http get from the device to the
server and pull down some XML, then
reload its own config.
Open an ssh connection to the server
to allow an admin to login to the
command line of the device and do
maintenance and troubleshooting
remotely.ie device => server <= admin and admin can get to bash command line or equivalent.
the device is a low powered embedded device that will be running linux. A solution in python would be preferable (im thinking something with paramiko for the ssh) but im open to other solutions. The main thing is there is there will be no technical users in the private network, so it should be able to plug into a consumer grade ADSL modem, get a DHCP address and all this should work. I can preload the device with anything before hand, for example ssh certificates for passwordless ssh etc.
anybody got any idea's?
Cheers
Mark
You can setup ssh tunnel (from python script or from console):
ssh -NR10022:localhost:22 foo#mainserver.com
Then you can simply login to main server and then ssh bar#localhost -p 10022
You should have ssh keys, so you don't have to put password (google about "ssh without password").
A more elaborate method might be some type of firewall hole punching.
On second though, maybe this is not necessary, since there is only one firewall involved. The trick is to get your embedded device to initiate an outbound connection first.