Regarding a proxy built using Netty. Note: Server C has a custom protocol. (not http)
Given a client 'A', Netty proxy 'B' and server 'C'
Will the server C be able to determine the IP of the Client A on an incoming connection?
Or will the client IP always appear to the Server to be B's IP?
Many thanks.
The server will not be able to see the client ipaddress. It will always only see the ipaddress if the proxy. One way to handle this is to encode the "original ipaddress" in the protocol so it can be extracted later at the server. For example in http you could use a header for this kind of thing. Same goes for smtp etc.
Related
I would like to know how internal communication links between private internal servers and a reverse proxy look.
When from my client (browser) I make a request to, say https://facebook.com, I hit Facebook's reverse proxy. I have two questions, when that reverse proxy gets a request and needs to forward it to the server that should handle it, does that sever it is forwarding the request to have a domain name or is it just an IP address ((user.facebook.com or useroffacebook.com v.s. 34.23.66.25 (DO NOT GO TO THAT ADDRESS I JUST MADE IT UP!!!)))? Also, does that connection use HTTP or HTTPS?
Like Kshitij Joshi already mentioned, it could be both.
A more detailed perspective for implementation:
reverse proxy should use IP addresses for routing so they are still working even if the DNS fails or is unavailable to the proxy for some reason.
internal traffic should also be encrypted (HTTPS). using plain text, even in internal networks, must be considered dangerous and is not recommended.
from my mindset you can replace the 'should' with a 'must'.
perhaps a silly question!!
in real networks, do servers send requests to each other? for example do a web server send request to another web server to fetch some data (for example .jpg and so on) ? or can a DNS server send request to another DNS server to ask an ip address?
i want to implement an algorithm for worm detection. i know servers often listen to a port and answer to the requests. so i think if a server initiate a connection , it is infected. but if in normal condition servers send requests to each other so servers can initiate connection in normal condition and so we can not say a server is infected when it initiate a connection.
thanks.
I have a requirement where I need to forward all the request from different sources to another network by grpc.
Request Server<-> Grpc Client <-> Internet <-> Grpc Server <-> Resource Server.
Request server and grpc client on same network.
Resource server and grpc server are on same network .
How to do I forward request server request to port that is sending data to grpc server ?
MY grpc server and client are in java so using grpc-java interface.
It sounds like you want a grpc-java-based proxy. "Grpc Client" in your diagram could be any HTTP/2 proxy. But you could use grpc-java to implement it.
I made an example generic proxy a while back. It does not need any information about the methods it is proxying. You basically just create a new outbound RPC for each inbound RPC and plug the inputs of one to the outputs of the other and vise versa.
Suppose computer A sends an HTTP request to a server B, and B wants C to answer it. Is it possible for C to send a response back to A without B intervention and without specific actions from A (as with a 3xx redirection)? Suppose C may not have a public IP address.
That's what a reverse proxy would do. Depending what platform you are on, there are a lot of options.
One way that works on many platforms is e.g. node-http-proxy that you could start on server B. In the most simple case, this one-liner would do:
require('http-proxy').createServer(81, 'serverb').listen(80);
It listens on port 80 and redirects to port 81 on serverb.
See https://github.com/nodejitsu/node-http-proxy for more options.
Of course, there are lots of well-established proxies with a lot more bells and whistles (although node-http-proxy can do https tunneling etc. as well), but configuring those can be more challenging that running this one-liner. It all depends on your use case.
Edit: Reading your comment, this can be done using direct routing. Your question is about HTTP (layer 7), and as direct routing works on a lower layer, higher-level protocols like HTTP work as well. Quote from http://horms.net/projects/has/html/node9.html:
Direct Routing: Packets from clients are forwarded directly to the
back-end server. The IP packet is not modified, so the back-end
servers must be configured to accept traffic for the virtual server's
IP address. This can be done using a dummy interface, or packet
filtering to redirect traffic addressed to the virtual server's IP
address to a local port. The back-end server may send replies directly
back to the client. That is if a host based layer 4 switch is used, it
may not be in the return path.
I understand that a SOCKS proxy only establishes a connection at the TCP level while an HTTP proxy interprets traffic at HTTP level. Thus a SOCKS proxy can work for any kind of protocol while an HTTP Proxy can only handle HTTP traffic. But why does an HTTP Proxy like Squid can support protocol like IRC, FTP ? When we use an HTTP Proxy for an IRC or FTP connection, what does specifically happen? Is there any metadata added to the package when it is sent to the proxy over the HTTP protocol?
HTTP proxy is able to support high level protocols other than HTTP if it supports CONNECT method, which is primarily used for HTTPS connections, here is description from Squid wiki:
The CONNECT method is a way to tunnel any kind of connection through an HTTP proxy. By default, the proxy establishes a TCP connection to the specified server, responds with an HTTP 200 (Connection Established) response, and then shovels packets back and forth between the client and the server, without understanding or interpreting the tunnelled traffic
If client software supports connection through 'HTTP CONNECT'-enabled (HTTPS) proxy it can be any high level protocol that can work with such a proxy (VPN, SSH, SQL, version control, etc.)
As others have mentioned, the "HTTP CONNECT" method allows you to establish any TCP-based connection via a proxy. This functionality is needed primarily for HTTPS connections, since for HTTPS connections, the entire HTTP request is encrypted (so it appears to the proxy as a "meaningless" TCP connection). In other words, an HTTPS session over a proxy, or a SSH/FTPS session over a proxy, will both appear as "encrypted sessions" to the proxy, and it won't be able to tell them apart, so it has to either allow them all or none of them.
During normal operation, the HTTP proxy receives the HTTP request, and is "smart enough" to understand the request to be able to do high level things with it (e.g. search its cache to see if it can serve the response without going to the destination server, or consults a whitelist/blacklist to see if this URL is allowed, etc.). In "CONNECT" mode, none of this happens. The proxy establishes a TCP connection to the destination server, and simply forwards all traffic from the client to the destination server and all traffic from the destination server to the client. That means any TCP protocol can work (HTTPS, SSH, FTP - even plain HTTP)