This plugin provides native NETMAP support for Zeek as a packet source.
Follow NETMAP's instructions to get its kernel module and, potentially, custom drivers installed. Then install this plugin through the Zeek Package Manager:
# zkg install zeek/zeek-netmap
To use NETMAP, Zeek needs read and write access to /dev/netmap. If
you give that permission to a user, you can run Zeek as non-root.
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:
zeek -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 Zeek 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 Zeek 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 (this should match what you set as lb_procs) that Zeek is configured to sniff.
On FreeBSD 13+, the netmap tools are available in the latest source code. Simply download the latest source code to get the app under /usr/src/tools/tools/netmap. Navigate to this directory and run make to build all of the tools:
# cd /usr/src/tools/tools/netmap/ # make Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/pkt-gen.o Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/pkt-gen Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/nmreplay.o Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/nmreplay Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/bridge.o Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/bridge Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/lb.o Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/pkt_hash.o Building /usr/obj/usr/src/amd64.amd64/tools/tools/netmap/lb
You can move the lb binary to wherever you want. In the following example, all of the netmap tools have been moved to /nsm/netmap. Running the following lb command line will create a "zeek" interface, connected to interface em0 with 4 netmap pipes (note this is not a service, the lb binary must be forked to the background or left running, which needs to be fixed):
/nsm/netmap/lb -i em0 -p zeek:4 &
Ensure the em0 interface is in promiscuous mode before running this. With lb running, use the following node.cfg to use 4 zeek processes to match the 4 netmap pipes:
[worker-1] type=worker host=localhost lb_method=custom lb_procs=4 interface=netmap::zeek
Then run zeekctl deploy and you should be up and running
Enjoy!