rawsocket 0.2

Raw packet socket for Linux

Only in linux, sorry.

Rationale

If you need raw sockets in your python script, you have to run it as root or make it SUID root. Alternatively, you can use file capabilities to grant extended priviliges to a binary. Unfortunately, this only works on binaries and not on scripts, which means you have to set the capability on the python binary.

How does it work?

As mentioned above, you can only set capabilties on a binary. Therefore, this module has a helper binary, which will get the RAW_NET capability. This binary is spawned by the rawsocket python module every time you create a new raw socket. The helper uses its capability to create the socket and then passes the file descriptor back to the calling program.

In linux you can pass file descriptors through unix domain sockets by using the sendmsg() system call and SCM_RIGHTS. See also fd passing.

Installation

Use PIP:

pip install rawsocket

Or use the standard method:

python setup.py install

This will install the extension module and the helper binary. But it will not set the file capability on the helper binary. You have two choices:

1. Grant every user access to the helper (simple, not recommended):

   setcap cap_net_raw+ep rawsocket-helper

2. Grant access only to users which are member of a specific group (recommended):

   chmod 750 rawsocket-helper
   chown root:yourgroup rawsocket-helper
   setcap cap_net_raw+ep rawsocket-helper

Example

import socket, rawsocket
fd = rawsocket.rawsocket_fd()
s = socket.fromfd(fd, socket.AF_PACKET, socket.SOCK_RAW)

You see easy as pie ;)

License

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.