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Keep the commands on setting up a netlink monitor interface in the README file.
147 lines
4.2 KiB
Plaintext
147 lines
4.2 KiB
Plaintext
Wireless daemon for Linux
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*************************
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Copyright (C) 2013-2014 Intel Corporation. All rights reserved.
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Compilation and installation
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============================
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In order to compile the source code you need following software packages:
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- GCC compiler
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- GNU C library
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- Embedded Linux library
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To configure run:
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./configure --prefix=/usr
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Configure automatically searches for all required components and packages.
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To compile and install run:
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make && make install
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Embedded Linux library
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======================
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In order to compile the daemon and control utility the development version
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of Embedded Linux library is required to be present. The development
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repositories can be found here:
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git://git.kernel.org/pub/scm/libs/ell/ell.git
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https://kernel.googlesource.com/pub/scm/libs/ell/ell.git
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The build systems requires that the Embedded Linux library source code
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is available on the same top level directory as the Wireless daemon
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source code:
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.
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|--- ell
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| |--- ell
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| `--- unit
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`--- iwd
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|--- src
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`--- client
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It is not required to build or install Embedded Linux library. The build
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will happen when building the Wireless daemon and it will then be linked
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internally.
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Kernel dependencies
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===================
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In order to use this daemon and control utility the kdbus kernel module
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is required. The development repositories can be found here:
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https://github.com/gregkh/kdbus
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https://code.google.com/p/d-bus/
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The daemon will start its own private bus that is located at the /dev/kdbus
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device hierarchy:
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/dev/kdbus
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|--- control
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`--- 0-iwd
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`--- bus
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When started as root, the new private bus will be /dev/kdbus/0-iwd/bus
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and it can be verified with the busctl utility from systemd:
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# busctl --address=kernel:path=/dev/kdbus/0-iwd/bus
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NAME PID PROCESS USER CONNECTION CONNECTION-NAME
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:1.1 62151 iwd root :1.1 iwd
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:1.2 62153 busctl root :1.2 sd-busctl
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Clients talking to the daemon must specifiy the private bus address.
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Netlink monitoring
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==================
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The included iwmon utility can be used to monitor the 802.11 subsystem
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generic netlink commands and events. It uses the nlmon kernel driver
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from Linux 3.10 and later. On startup network monitor interface named
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named 'nlmon' is created unless another interface name is given on the
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command line. If the monitor interface was created by the iwmon utility,
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it will be removed on program exit.
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Manually the monitor interface can be created using the following
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commands:
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ip link add name nlmon type nlmon
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ip link set dev nlmon allmulticast on
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ip link set dev nlmon up
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It is possible to create netlink traces in PCAP format using tcpdump
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and then read them via iwmon utility:
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tcpdump -i nlmon -w trace-file.pcap
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The resulting PCAP files will use Linux cooked packet format containing
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packets with ARPHRD_NETLINK type. They can be read using iwmon:
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iwmon -r trace-file.pcap
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At this time iwmon is not able to write PCAP files by itself. This might
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change in future versions.
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When also the authentication protocol traffic on port 0x888e (ETH_P_PAE)
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is needed, then a second capture is required:
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tcpdump -i any 'ether proto 0x888e' -w trace-pae.pcap
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It is possible to combine these two PCAP files using the mergecap utility
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and create a combined trace file:
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mergecap -F pcap -w trace.pcap trace-file.pcap trace-pae.pcap
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This will create a trace.pcap file that includes the complete picture
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of nl80211 netlink traffic and authentication messages. All packets are
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merged in chronological order based on timestamps.
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Unfortunately it is not possible to instruct tcpdump filtering to do
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this in a single capture. Post-processing of the PCAP files is required
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at the moment.
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Simulating devices
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==================
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The Linux driver mac80211_hwsim provides the functionality to simulate
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Wireless devices using fake virtual air. Just load the module.
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modprobe mac80211_hwsim radios=0
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Provding the radios=0 is important since otherwise it starts out with
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two new Wireless radios by default.
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With the provided hwsim utility it is now possible to add and remove
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virtual radio devices.
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hwsim --create
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hwsim --destroy=<radio-id>
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The radio id assigned to each virtual device is its internal id used
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by the Wireless device.
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