HTTP Filter

eBPF application that parses HTTP packets and extracts (and prints on screen) the URL contained in the GET/POST request. eBPF HTTP Filter - Short Presentation

Usage Example

$ sudo python http-parse-sample.py 
GET /pipermail/iovisor-dev/ HTTP/1.1
HTTP/1.1 200 OK
GET /favicon.ico HTTP/1.1
HTTP/1.1 404 Not Found
GET /pipermail/iovisor-dev/2016-January/thread.html HTTP/1.1
HTTP/1.1 200 OK
GET /pipermail/iovisor-dev/2016-January/000046.html HTTP/1.1
HTTP/1.1 200 OK

Implementation overview

The implementation is split in two portions:

• the former that exploits eBPF code;
• the latter that performs some additional processing in user space (the python wrapper);

First part: eBPF filter

This component filters IP and TCP packets containing the "HTTP", "GET", "POST" strings in their payload and all subsequent packets belonging to the same session, having the same (ip.src, ip.dst, port.src, port.dst) tuple.

The program is loaded as PROG_TYPE_SOCKET_FILTER and attached to a socket, bind to eth0 by default. You can append -i option to http-parse-sample.py to specify preferable network interface.

Matching packets are forwarded to user space, the others are dropped by the filter.

Second part: python code in user space

The Python script reads filtered raw packets from the socket, if necessary reassembles packets belonging to the same session, and prints on stdout the first line of the HTTP GET/POST request.

Author information

This package was written by Bertrone Matteo, and National Cheng Kung University adopted it for education purpose.

References

• BPF: A Tour of Program Types