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Have you heard about Russia blocking IPs of Amazon’s servers (millions of them) in order to block messenger Telegram? There are a lot of cases when people are saying that their unrelated to Telegram applications, but located on Amazon servers, laid down as well as a consequence.
I was wondering if this teqnically possible situation. If I, for example, use Amazon’s server for my app, do I share an IP with others? Does it mean that if somebody blocks this IP to block another app, then I screw up as well? Or these are all fake sayings, and block is targeted enough to avoid this?
Is it possible to share IP on server among multiple applications?
Definitely. This is why transport protocols like TCP and UDP use port numbers. These port numbers serve as sub-addresses for the IP.
Some application protocols can even share the same IP address and port combination, like HTTP. An HTTP vhost (or a proxy) can direct the request to the desired server instance depending on the URL parameters.
So, when Internet censorship is applied on the IP address basis, it's not uncommon to filter more than intended.
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At start I need to mention that I'm a complete newbie if we talk about networking, so don't judge me ;)
Problem:
I've got a Flask application running on my raspberry pi. I can access it via web browser using raspberry_ip:5000. I need to access this app outside of my local network.
I used to have port forwarding on my router so whenever I typed in browser my_public_ip:5000 I could use my app running in local network. However as many people say, port forwarding isn't the best and most secure method.
And here is my question: Can I access app on my raspberry using VPN (Private network where is only raspberry, and there is not risk of some kind of attack), becasue I guess it would be much more secure than port forwarding.
Maybe there is some other method to access this flask app outside of my network, without risking an unathorized access to local network.
sorry for my poor english
As long as the following are set, this solution sounds fine to me.
Your Flask application is secured by user authentication.
The Web communication is secured by an SSL certificate(using server HTTPS).
In order to be more secure, I would put a Web server in front of Flask, such as Nginx, therefore you are exposing the Nginx process to the Internet rather than Flask.
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When I do socket programming, I found at least one computer has to have a public IP to make the connection (or reverse connection). I'm wondering if it is possible for 2 computers that are behind different routers to connect to each other (and they don't have port forwarding and don't use proxy)? If that's not possible, how bit torrent works for computers that are behind routers? Does it mean the computers that are behind different routers cannot share among each other?
Bittorent clients are using a protocol named uPNP, that tells router to redirect specified port in bittorrent client to computer that runs client.
Here is more information about protocol.
https://en.wikipedia.org/wiki/Universal_Plug_and_Play
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I want to find out a person's ip address who is abusing me on facebook. Whenever I log into facebook he shows up in the chat and threatens me. I am kinda hacker but how can I find his ip address in chat using wireshark or something. He is really starting to piss me off. Please HELP.
Wireshark is a fantastic tool but will only be able to monitor network traffic passing through your own network - in this instance, you would be able to monitor your own side of the Facebook Messenger conversation.
There is no direct TCP/IP connection from this person's computer to your computer involved. Both they and you connect to Facebook's web servers and messages are sent and received using HTTP protocol and AJAX.
Most communication services operate in this way these days, partly to protect the privacy of its users, partly for improved performance and reliability, and partly for regulatory compliance. Possible solutions normally include:
Reporting abuse to the service provider and in most cases they will be pleased to investigate it for you;
Blocking the person from contacting you in future using the tools built-in to the service;
Reporting abuse to your local Police, who can legally obtain the IP address and login history from Facebook. They will not pass this information onto you for retribution but if sufficient evidence is available the person bothering you could be arrested and charged for harassment, malicious communications, defamation and/or breach of peace, depending on the local laws where you/they live.
Reference: CyberSmile.org: CyberBullying and the Law
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Device A -> Router -- Internet -- Router <- Device B
I know VoIP normally direct connect two device. But I don't know how they get connected. I assume there's a server on internet.
For others have questions like me:
http://en.wikipedia.org/wiki/NAT_traversal
If the two routers are doing NAT, then yes, probably there is a server in the middle. So, each device only has to make a connection OUT through the router, which is no problem. Then the server can pass data back and forth between them.
But it is also possible to make a connection directly, even if both routers are doing NAT. In order for this to work, at least one router needs to have a port forwarding configuration set up, to allow an inbound TCP connection from the other to be forwarded to the correct device, on some specific port. This port forwarding could be manually configured on the router or it could (depending on the router) be set up automatically by the device, using UPnP protocol (if the router supports it).
Even then, usually there's a server in the middle that both devices might communicate with to find out the IP and port number used by the other device. But if you have other ways of knowing this information, it's not necessary.
Hope this helps.
I assume since you mention VOIP you are wondering how two IP Phones connect?
Phone is configured with the IP address of a PBX. Phone 1 makes a call. The digits are sent to the PBX. The PBX examines the phone number dialed and looks up the phone number in something called a dial plan. That dial plan tells the PBX the path to get to the phone number dialed. It may say open a connection to the phone company or it might tell the PBX the IP address of the other PBX.
If it gets the IP address of another PBX it sends a SIP message to the remote PBX informing that it has a incoming call. The remote PBX accepts the SIP message and sets up the call and tells the remote phone to ring. When the phone is answered the two IP PBX's agree that the call is set up and tells each phone the ip address of the other phone and allows them to communicate directly.
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Hi this will be an easy question.
Ftp, as an example, works on ports 20, 21. How many different people can connect to the same ftp server on the same port (21) at the same time?
As many as the server and the server OS can handle. There is no specific limit.
All the comments citing specific clients are incorrect, as is the one stating '1-8 as far as I know.' The comment about 'FTP Site Default settings' only applies to Microsoft IIS.
Port is the virtual interfacing used to differentiate services. In your case FTP server listen on particular port 21 which differentiate all other services/servers running on the same system listening to the same IP address (eg: DHCP server on 67 etc.,).
So the port are used only at Transport and Application layer (to bind to the particular port). The number of connections is limited with the help of "listen" system call (in case of linux), which will used in server binding.
Note: Observe any PCAP traces and socket programming to understand the usage of port.