I was getting a bit confused on using of raw sockets and libcap. Can, anyone in simple point out advantages of using both. I read few links, but, its making me confused.
libpcap uses different mechanisms on different operating systems. On Linux, it uses PF_PACKET raw or cooked sockets, depending on whether it knows about the Linux link-layer type (ARPHRD_ value) for the interface and whether interfaces of that link-layer type produce a useful link-layer header (PPP interfaces don't, so you can't see the network-layer protocol identifier). On Irix, it uses PF_RAW sockets with the RAWPROTO_SNOOP protocol. On other systems, it doesn't use raw sockets at all.
Raw sockets can be used for a number of purposes, such as sending and receiving raw IPv4 packets without having to worry about the link-layer (i.e., they plug into the IP layer rather than into the network device driver). If you need access to the raw link layer, raw sockets on most OSes don't support that (Linux and Irix being obvious exceptions, as per the previous paragraph), but libpcap does.
"libpcap" and "raw sockets" are different topics.
Libpcap is a packet capture library for linux which is used to capture the traffic/packets that pass through a network interface like eth0.
On windows the Winpcap library does the same thing.
Raw sockets are a feature of the socket api provided by the OS that can be used to send packets with headers defined by the application and not the OS. So using raw sockets we can specify the IP , TCP headers and send the packets.
Raw sockets are available on Linux since all time. On Windows raw sockets were available only in Windows XP and Windows XP(SP1).
On windows the winpcap library has a feature to send packets with arbitrary content , which means raw socket functionality can be achieved with winpcap on Windows.
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My passive network monitoring application needs packets to be captured from network interface (at higher packet rates). The packet capture module should be able to call a monitoring function upon capture of each packet (and also write the packet in to pcap file).
I thought of using DPDK as the packet capture module in my monitoring application (as we use pcap_loop and pfring_loop in libpcap and pfring respectively), but I am not sure whether this is one of the use cases of DPDK, or, is DPDK meant to be used like this?.
So my questions are..
Can I use DPDK to fulfill my requirements?, If yes how to start?.
OS: Linux.
Karnal version: 4.
DPDK version: Latest stable.
Capture on physical device.
The capturing application has root privileges and will be used by the network administrator (as part of passive asset discovery).
I want to use DPDK because it supports capture at line rate upto 10 Gbps
Thank you.
Based on the updates and clarification in comment the request is Can one replace an existing application which PF_RING API calls with DPDK API which is written in C?. Simple answer to it is yes it can be done.
Here is how one should start
identify the Platform (preferably Linux/BSD, windows 21.02 is still work in progress)
identify the processor list of supported CPU
Identify a NIC to use from LIST of DPDK NIC
Set up the Linux environment with Linux Enviroment
Explore basic example/skeleton for basicfwd usage
get the start of ethernet header for packet using DPDK API rte_pktmbuf_mtod. There are many samples in DPDK/examples folder which does the same.
Invoke the packet processing function logic between rx_burst and tx_burst of example/skeleton.
Newer versions of libpcap can themselves use DPDK, at least on Linux. The libpcap on your system might, or might not, be configured to use it. (There are also versions of libpcap modified to use PF_RING.)
I made a simple Instant Message Chat Client and Server on TCP, that both run off Adobe AIR. It works great and it was a interesting way to learn basic networking programming.
My Question: Is it possible to change the data in the packet sent from the Chat Server before it arrives at the Client without using the Server or Client to do so? Like perhaps a program?
I am new to Network programming so I apologize if this is a dumb question.
Your question is very broad. So the answer is broad as well. Yes. It's possible.
For that you need to get the packets between the client and server to pass through a third program. There are quite a lot of ways to achieve that. Here's non-exhaustive list:
First, on your own machines (client/server) you could get access to the packet from the operating system using various low-level APIs. For instance iptables+nfqueue in Linux or the Windows Filtering Platform on Windows.
Second, you could get access to the packets by intentionally having them communicate through some proxy program which may or may not reside on the same server as the client or the server.
Third, you could get access to the packets by picking them up from the network itself. For instance, you could set up some Linux machine as a router and have it sit between the client and the server (as long as they're not on the same machine). That Linux machine will now have access to all of the packets that pass through it, and it can pass them to various user-space programs using hooks such as the previously mentioned nfqueue.
I am trying to understand the purpose of websocket multiplexing extension, the main purpose what the document states is to use a single same origin physical websocket connection to the server while each browser tab uses a logical connection multiplexed on top of physical connection. I see another alternative using which we can accomplish this behavior today, the approach is to launch a shared web worker which opens the websocket connection and let each browser tab send and receive message to/from this worker. i have not tried this yet and i wonder will this work at all.
Your question reflects a misunderstanding of the problem the WebSocket Multiplexing Extension is trying to solve.
The base WebSocket spec (RFC 6455) defines a protocol for bi-directional exchange of data over TCP/IP. A WebSocket starts as a normal HTTP request / response. In this exchange, the client and server negotiate to switch to the WebSocket protocol. After the switch, the client and server exchange data frames over the TCP/IP connection. This creates a bi-directional data stream between client and server.
A drawback of the base protocol is that it supports only a single stream of data flowing in each direction. The multiplexing extension augments the base protocol, by allowing the client and server to create multiple "channels" over the same TCP/IP connection.
So the purpose of the multiplexing extension is to allow multiple WebSocket channels to run over the same TCP/IP connection. That's all.
Having multiple browser tabs (or web workers) share a single TCP/IP connection is just an example of how multiplexed websockets might be used. In standards terminology, it's just "informative" (descriptive), not "normative" (a required part of the spec).
Which is best tcp socket server to testing html5websocket? I developing a html5socket based client that will interact with tcp. So I want first a testing server. I am good in PHP but not in sockets programming. So I used PHPwebsocket downloaded from google code. I tried it using its own client and server for testing but it suddenly disconnects and not work as intended so is there any other socket server to test HTML5 websocket client? Which one is better, I can use a python based, or java based tcp server or if in PHP then that can be more convenient. And please tell me what else I need to test HTML5 websocket. I am newbie in sockets. So my concepts are not so clear.
thanks for any advise.
If you want to self host then:
pywebsocket - Python
jwebsocket - Java
jetty with WebSockets - Java
You could connect to the Pusher hosted WebSocket API to see if you can connect. More information on the endpoints and Pusher protocol here:
http://pusher.com/docs/pusher_protocol
You would need to sign up for a free Pusher sandbox account to do this though.
You say you want to "interact with tcp". Do you have specific protocols in mind? If using JMS, XMPP, or AMQP, the Kaazing WebSocket Gateway provides these industry standard APIs and protocols in the browser out-of-the-box. For example, using JMS, you can build pretty complex messaging applications without a single line of server-side code. Everything can run in the client (typically in JavaScript in the browser).
Here are some examples showcasing the power of extending rich business protocols all the way to the browser.
Also, the Kaazing gateway comes with free development license; fully functional server for up to 50 concurrent connections, no functionality or time restrictions.
I already have a server with port and want to write a web app to get the information form the port. Will this be possible with WebPorts?
The Client doesn't even need to talk back to the server, which is the whole point of websockets I would imagine, but since I already have the ports setup, I might be easier and cleaner to just connect and get the info without having to refresh.
WebSockets are not intended as clear TCP channels over which other existing protocols can be implemented.
WebSockets are designed to allow messages to be sent between a client and server, where an event is raised each time a message is received.
Hence a WebSocket client cannot simply connect to an existing TCP server - that server also has to speak the WebSocket protocol.
You could of course write a WebSocket-based server that does nothing but act as a proxy to existing network services.
I think you want websockify which is a WebSocket to plain TCP socket bridge/proxy. It also allows sending and receiving of binary data with the older version of the WebSocket protocol which hadn't yet added direct binary data support.
Disclaimer: I created websockify.