I am aware on how to send files through a socket in perl (server, client)... but I was wondering if anyone could explain or give me a reference on how to send image files through a socket
If you are "talking to the browser", you probably need to speak HTTP? If so, you need to send the correct Headers (e.g Content-Type: image//jpeg) before sending the raw image data.
Related
I am trying to implement a program that is able to send TCP packets alone by itself. Ideally I want to send a packet to a port in a computer and have it processed. This means that I am trying to do it without having a client/server files pair.
However, I am finding it really hard to do this as anywhere I look there is mention of both the client and the server files. And if I try to run the client file or the server files by themselves, it doesn't even work as they depend on each other.
Is it possible to do what I want?
Not sure why you want to do that. But in order to send such packets, you need to use API for IP raw socket (SOCK_RAW), instead of TCP.
So you can send IP packets with payload of your "crafted TCP".
I have '.pcap' files that were generated by Tcpdump. I have been looking for a way with PHP to read data in the files. I have tried several methods available, but the only thing I was able to see was that there were some number of packets with a timestamp against each packet. I tried to read further but it was all in some binary.
Just wanted to ask if anyone out there has experience with packet capture. Would be great help.
I have tried these methods so far:
https://github.com/zobo/php-pcap
https://code.google.com/a/eclipselabs.org/p/php-pcap-analyzer/
and
http://systemsarchitect.net/parsing-binary-data-in-php-on-an-example-with-the-pcap-format/
http://systemsarchitect.net/
Thanks in advance :)
I was able to see http requests from my client machine to internet by using PHP's unpack() function and fread() combined. The libraries mentioned above are also useful to retrieve other information for example the ip addresses of client and server machines with timestamps
But I wasn't able read the responses. That is because the data returned from internet servers to remote client is encrypted and PHP is not a good technology to retrieve this data.
Is it possible to dump contents of tcp recv/send to a pcap file and then have wireshark analyse this. I want to do this because I want to log an applications conversations in order to debug issues but I don't want to have to write my own parsers (wireshark already supports it) and don't necessarily trust the application to parse frames correctly.
What follows is based on work that I've done exclusively on Windows.
I can't speak to how well any of this might apply to other systems.
FWIW, I would suggest editing your question (or at least tagging it)
to be more clear about what OS you're targeting.
If you are talking about writing what's received directly from a TCP client to a pcap file, the answer is no. The pcap file format requires at least some networking headers, e.g., the IP and TCP headers, in order for the file to be valid.
There are four approaches I see.
You could fake these headers for each read from the socket. This wouldn't necessarily require a lot of work, but it would require some knowledge of the relationships between the network header, the transport header, and the payload (i.e., your data) in order for everything to work right. If you're only interested in analysis of the payload in Wireshark, this might be a valid approach. However, if the analysis you're wanting to do in Wireshark is network analysis (i.e., analysis that includes the network headers), then you'll want to avoid this option and figure out how to capture the network headers directly.
You could use a raw socket to capture network traffic at the network layer. This will give you the IP packet - IP header, TCP header, and payload. You could dump this to a pcap file using LINKTYPE_RAW as the link-layer header type, and Wireshark will read the file fine. I've used this approach before.
The third approach would be to use WinPcap to collect your data. This is the same software that Wireshark uses behind the scenes to collect the data, and it's the approach I'm using now. If you have Wireshark installed, the WinPcap is already installed, too. WinPcap has a simple API with numerous examples for opening an interface, collecting the data, and dumping it to a pcap or pcap-ng file.
The fourth option is the simplest...just use Wireshark to collect the data simultaneously with your application.
HTH.
I have an image steganography module in my project. It works perfectly fine on a client side implementation.
What I want to do is, after the message is embedded in the image, to send the image to a server. How can I do this?
There are various way. You can FTP that to a server, send it as a mail attachment, open a socket and send it to the server N bytes at a time...
You should be a bit more clear about your set-up.
I have a remote server with some files. I want to use AsyncSocket to download a file, chunk by chunk. I would like to send HTTP requests with ranges through the socket and get the appropriate chunks of data. I understand how to do this on localhost, but not from a remote server. I really don't know how to use the connectToHost and acceptOnInterface (previously acceptOnAddress) methods.
Please help
Thanks
AsyncSocket is a general purpose data connection. If you want it to talk HTTP, you'll need to code the HTTP portion yourself. You probably don't actually want this; NSURLConnection should do what you want, provided the server supports it.
What you're asking for is the Range: header in HTTP. See 14.35.2 in RFC2616. You just need to add this header to your NSURLRequest. Again, this presumes that the server you're talking to supports this (you need to check the Accept-Ranges: header in the response).
There's a short article with example code about this at Surgeworks.
You should also look at ASIHTTPRequest, which includes resumable downloads and download progress delgates, and can likely be adapted to doing partial downloads. It may already have the solution to the specific issue you're trying to solve.