Bro::Netmap

This plugin provides native netmap support for Bro.

Installation

Follow netmap’s instructions to get its kernel module and, potentially, custom drivers installed. The following will then compile and install the netmap plugin alongside Bro, assuming it can find the netmap headers in a standard location:

# ./configure && make && make install

If the headers are installed somewhere non-standard, add --with-netmap=<netmap-base-directory> to the configure command. If everything built and installed correctly, you should see this:

# bro -N Bro::Netmap
Bro::Netmap - Packet acquisition via netmap (dynamic, version 1.0)

To use netmap, Bro needs read and write access to /dev/netmap. If you give that permission to a user, you can run Bro as non-root.

Usage

Once installed, you can use netmap interfaces/ports by prefixing them with either netmap:: or vale:: on the command line. For example, to use netmap to monitor interface eth0:

bro -i netmap::eth0

Netmap does not enable promiscuous mode on interfaces, you’ll have to do that yourself. For example, on Linux:

ifconfig eth0 promisc

To use it in production with multiple Bro processes, use a configuration similar to this in node.cfg:

[worker-1]
type=worker
host=localhost
lb_method=custom
lb_procs=<number of processes, like 16>
interface=netmap::<interface name, like p2p1>

This will start up Bro processes sniffing on netmap pipes attached to the interface. In order to balance packets from the interface across those pipes you will need to run the tool named lb that is included in the apps/lb directory of the Netmap distribution. Make sure that you instruct lb to split the packets into the same number of pipes that Bro is configured to sniff.

Enjoy!