I want to use tcp fast open in springboot, in order to client can take request in tcp syn packet. But how can I open tfo in springboot as a server.
I search the question in Google but can not find any infomation
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Even after lots of googling, I'm pretty naive about quic.
I'm specifically looking into lucasclemente/go-quic.
Should quic servers use 443? If so, will it fallback to http2 & tls 1.2?
I'm speaking generally. Not for that specific go package. But if you have specifics for that go package, that would be great.
Yes, I realize quic is still young and not necessary yet. I'm simply curious and couldn't find that specific answer. Thanks!
Quic servers can use any port they want; 443 is often used, but this is not necessary at all. Note we're talking about UDP ports, not TCP ports.
A QUIC server cannot fallback to HTTP2 or TLS 1.2, because if the client sends a QUIC request, the server can only respond with a QUIC response. If the browser doesn't support QUIC, it will not send a QUIC request in the first place, so there is no issue at all.
I think you are assuming that a QUIC server runs (or can run) on the same port as HTTPS and therefore has to generate either a QUIC or an HTTPS response; this is not the case, as QUIC is running over UDP, not over TCP (like HTTP and HTTPS do). TCP ports and UDP ports are different address spaces, so one can run an HTTPS server on tcp port 443 and simultaneously run another QUIC server on udp port 443.
The website is developed in SpringBoot and deployed in Linux server. When I open one website page in Chrome, and I open TCP Viewer, I see that there are multiple TCP connections from my computer to the server. They are using totally different ports.
And I check the network tab in Chrome DevTool, I see there is Keep-Alive in the requst header. I guess it is using Http 1.1 and long connections.
So this confused me. Since it is long connection, all the content should be through one TCP connection, why are there so many TCP connections?
While HTTP/1.0 and HTTP/1.1 support persistent connections where multiple HTTP requests are handled within the same TCP connection, these requests are still handled on after each other within the same connection. If many resources are needed from a site this sequential loading using a single TCP connection would be too slow. Thus parallel loading using multiple TCP connection is done. Since most sites load many resources (main HTML, various CSS, JavaScript, images, fonts...) one sees multiple TCP connections used with most sites.
With HTTP/2 parallel loading within a single TCP connection is supported. In this case one will usually see only a single TCP connection to a site. Of course, if resources are loaded from multiple sites (i.e. ads, tracking ...) one will also see multiple TCP connections again - but only one per destination if HTTP/2 is used for the specific destination.
I have an application that uses secure websockets that I am having trouble with.
I would like to use wireshark to debug the problem, however I can not figure out the correct parameters to put into wireshark to monitor and display a secure web socket connection using HTTPS.
Does anyone know of a wireshark filter that would accomplish what I need and if I need to do anything else to monitor secure websockets using wireshark?
If you want to monitor a WebSocket connection between the browser and a server, then it might be easiest to use the Chrome or Firefox developer tools.
The following applies to WebSockets using the HTTP/1.1, it might not work for WebSockets bootstrapped with HTTP/2 (RFC 8441).
The following steps describe the necessary steps for Wireshark 3.4.0, but it will likely work for newer versions as well.
Because secure WebSocket connections (URI scheme wss) tunnel the data over TLS, the general steps for decrypting TLS traffic with Wireshark apply, see the Wireshark wiki article.
Depending on your setup these steps and capturing of packets might have to be performed before the WebSocket server is started and before the connection to the client is established.
WebSockets use TCP for transmission, therefore you have to use a Wireshark display filter which only shows the relevant TCP segments.
For example if your WebSocket server is listening on port 443, you could use the following to show only incoming and outgoing packets to that port:
tcp.port == 443
If you performed the previous steps correctly and click on one of the TLS "Application data" packets, it should show a "Decrypted TLS" tab at the left bottom corner:
If you are using the well-known port 443, then Wireshark is able to detect the HTTP upgrade to WebSocket on its own.
However, if you are using a custom port, you have to tell Wireshark how to decode the packets. To do so right click on any of the packets and select "Decode As...":
In the new dialog, click on "(none)" in the "Current" column and select "HTTP" from the dropdown:
You should now see the HTTP upgrade to the WebSocket protocol and all of the WebSocket messages. Additionally you can inspect their content:
I'm working on mac os x. I'm trying to build a cocoa app working on a storage server (similar to Dropbox) that does something whenever a file is added,removed..I have already a client app installed on the mac that shows all the files stored on the server and I need to listen to the port that the server is using to send changes notification to the app. I've started following some tutorials for Sockets but I get "Address already in use".
The Question: are sockets the only way to listen to a port and if yes is there a way to build a socket to listen to an already existing server/client connection?
If a process is already listening on a port then no other process can bind(2) to that port. Alternatives would include to have a proxy listen on that port that would deal with events and then pass them on elsewhere (the client app may not play well with this), or to use firewall rules to duplicate the packets to some other port that your app would then listen on, or maybe the client application issues notifications that then can be acted on.
https://github.com/thrig/lognots
Is one way to inspect the notifications available.
Remember that listening on a port is how you prepare to receive incoming connections. It is not necessary to receive data — once a connection is established, data can flow in both directions! It is almost never appropriate for a client application to listen on a port; that's usually only appropriate for server applications.
With that in mind: Your client application should connect to a port on the server, and the server will send data to the client as appropriate.
We are building a large slanger cluster and would like to use websocket TCP as client connectivity indicator, so whenever a client is offline we could tell from the channel state. Is there an API to check online/offline status of a channel?
Besides that, is there a way to get the TCP fd of the websocket beneath a channel? So I can grab some statistics of that long connection.
OK after reading through Slanger's source code I have concluded that it is not possible. I modified slanger/lib/subscription.rb to have my own customized tcp status exposed via http api.