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securityonion/salt/deprecated-bro/policy/securityonion/bpfconf.bro
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2020-01-30 09:45:02 -05:00

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##! This script is to support the bpf.conf file like other network monitoring tools use.
##! Please don't try to learn from this script right now, there are a large number of
##! hacks in it to work around bugs discovered in Bro.
@load base/frameworks/notice
module BPFConf;
export {
## The file that is watched on disk for BPF filter changes.
## Two templated variables are available; "sensorname" and "interface".
## They can be used by surrounding the term by doubled curly braces.
const filename = "/opt/bro/share/bro/site/bpf" &redef;
redef enum Notice::Type += {
## Invalid filter notice.
InvalidFilter
};
}
global filter_parts: vector of string = vector();
global current_filter_filename = "";
type FilterLine: record {
s: string;
};
redef enum PcapFilterID += {
BPFConfPcapFilter,
};
event BPFConf::line(description: Input::EventDescription, tpe: Input::Event, s: string)
{
local part = sub(s, /[[:blank:]]*#.*$/, "");
# We don't want any blank parts.
if ( part != "" )
filter_parts[|filter_parts|] = part;
}
event Input::end_of_data(name: string, source:string)
{
if ( name == "bpfconf" )
{
local filter = join_string_vec(filter_parts, " ");
capture_filters["bpf.conf"] = filter;
if ( Pcap::precompile_pcap_filter(BPFConfPcapFilter, filter) )
{
PacketFilter::install();
}
else
{
NOTICE([$note=InvalidFilter,
$msg=fmt("Compiling packet filter from %s failed", filename),
$sub=filter]);
}
filter_parts=vector();
}
}
function add_filter_file()
{
local real_filter_filename = BPFConf::filename;
# Support the interface template value.
#if ( SecurityOnion::sensorname != "" )
# real_filter_filename = gsub(real_filter_filename, /\{\{sensorname\}\}/, SecurityOnion::sensorname);
# Support the interface template value.
#if ( SecurityOnion::interface != "" )
# real_filter_filename = gsub(real_filter_filename, /\{\{interface\}\}/, SecurityOnion::interface);
#if ( /\{\{/ in real_filter_filename )
# {
# return;
# }
#else
# Reporter::info(fmt("BPFConf filename set: %s (%s)", real_filter_filename, Cluster::node));
if ( real_filter_filename != current_filter_filename )
{
current_filter_filename = real_filter_filename;
Input::add_event([$source=real_filter_filename,
$name="bpfconf",
$reader=Input::READER_RAW,
$mode=Input::REREAD,
$want_record=F,
$fields=FilterLine,
$ev=BPFConf::line]);
}
}
#event SecurityOnion::found_sensorname(name: string)
# {
# add_filter_file();
# }
event bro_init() &priority=5
{
if ( BPFConf::filename != "" )
add_filter_file();
}